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  1. #1

    Default Megasquirt 4A-GZE (Caution: Wordy)

    The purpose of this thread is to chronicle my adventures in getting my MR2 to run with a Megasquirt-II engine management system. Obviously this is specific to my car. Iím also posting here in the hopes that if I have some information that is wrong someone will let me know before I do any real damage. Updates here will be slow! I will be taking my time (what little of it I have) and I have to wait until I can park the car for a few weeks before trying to get the MS installed.

    So as some of you know I have a MK1 MR2 with a 4A-GZE swap. The engine that was swapped in was a North American model (AFM, no under piston oil squirters, distributer). I also have a spare 4A-GZE that came from Japan that has been sitting for a few years. Initially I was just going to swap the engine in to get a small increase in performance but I ended up holding back on that. Situations in my personal life took priority. However, one day while trying to figure out why my car wasnít performing as I thought it should I took off the supercharger and found that the rotors were all scratched up. I swapped the supercharger from my spare engine onto the car and things were happy again.

    Obviously, like any other moving part, the supercharger wears out. Iím sure Iíve still got plenty of time on the one that is in the car now. Toyota will sell me a new one for $4500, and I could buy at least three more complete engines for that price. There are seals available for the outer housing, but no one is supplying the bearings or the rotors. So I have decided that the best route to go is to replace the supercharger with a turbocharger. Iíll be honest and say that this is still a ways off as I simply do not know enough about turbocharging theory to make an informed decision as to what turbo setup to use.

    It was along this line of thought that I came to the conclusion that I needed and aftermarket ECU to run the thing. I started looking at the commercial units and seeing what they offered. Like many before I had looked at the Megasquirt but had decided that it didnít do everything I wanted it to. I did look at it to see if there were any updates and found that the thing had make huge leaps since I last looked at it (for reference, when I had last looked at it it only did fuel, no ignition). I started to research it and spent a couple weeks going through all the information of how it works and what it will do.

    Finally I came up with a plan. I would get the MS to work on the engine that is in the car now and then rebuild the other engine with a turbo in mind and swap the MS to that engine. I went to DIYAutoTune and placed an order. I ordered the MegaSquirt-II PCB3 Unassembled Kit, the JimStim 1.4 unassembled kit, the 4 bar MAP sensor with Barometric Correction and the Zeal Engineering Daughterboard.

    I still have some more to order (like the wideband O2 system), but I wanted to be a little kinder on my wallet and I donít need everything right now. I am planning for this to take some time to install in the car and get it running so I have to wait till summer when I can ride my bike to work so the car can stay parked for a week or two.

    I am confident in putting this unit together has I have had many years experience with building circuits in industry. The first thing to do is research. Then build the stimulator, then the MS unit, then get it all working on the bench. Finally install it in the car and start tuning. For me I think the tuning will be the hardest part.

    I will try to break the systems down as much as I can. If things seem to be oversimplified it is simply because I want to make sure I understand it.

    Fuel delivery

    Fuel management is actually fairly simple. Basically the ECU inputs data from sensors on/in the engine and then determines via lookup tables how much fuel should be injected into the engine. Tuning is done by changing the values in those tables. The MS looks at several engine conditions. There is the Throttle Position Sensor (TPS), the Coolant Temperature (CLT), the Intake Air Temperature (IAC), RPM, and an Exhaust Gas Oxygen Sensor (EGO).

    On top of the lookup tables there are other variables taken into consideration. For example an engine that hasnít reached optimal operating temperature can have a warmup enrichment. When the TPS is open far enough there can be an acceleration enrichment. The EGO data is used to correct the amount of fuel injected (to a certain extent), and so on.

    The MS pulses the injectors on and off to control the amount of fuel injected. The width of the on pulse (how long it is activated or on or open) determines how much fuel gets in per pulse. Changing this pulse is known as Pulse Width Modulation (PWM). An injector that spends half of a cycle open and half closed is said to have a 50% duty cycle. The higher the duty cycle the more fuel is injected. If an injector is at 100% duty cycle then it is open all the time. If this condition occurs and the engine still doesnít have enough fuel, you need bigger injectors.

    The version of the MS that I am getting has the flyback circuitry built in so it will run both high and low impedance injectors. I am getting the MS-II which can only batch fire two banks of injectors. The two banks can be fired together or in an alternating pattern. However, sequential fuel injection is not available. The MS-III will have it but it is still in the testing phase.

    The firmware that I will load onto my MS will be the MS2extra. This gives the MS a lot of capabilities. It contains code for wall wetting (fuel that doesnít get sucked into the engine but stays on the walls of the intake) and such. I havenít had a chance to play with it much yet as the Tuner Studio software doesnít do much unless you have a MS connected.

    Ignition

    I have four options when it comes to ignition triggering:

    1) I have a distributor from a 4A-GE that has the standard 4+1 sensor VAST setup. What this means is that there are two wheels in the distributor, one has four teeth and one has one tooth. The four toothed wheel triggers a sensor (signal labelled Ne) at every half crankshaft rotation, which is an ignition event. When cranking or the jumper is inserted into the test connector the igniter fires the coil each time that the sensor detects a tooth. The spark then travels from the coil to the distributor where it is routed to the correct plug by the distributor. After cranking and the engine is running the ECU then adjusts the timing by taking over the triggering of the ignitor based on various engine sensor feedbacks. The other wheel has one tooth on it and as far as I know the ECU just uses this for injector and ignition timing adjustments (this signal is labelled G). According to everything Iíve read the 4A-GE is the only engine that has the 4+1 with the VAST ignition. All the others just have the single four toothed wheel. I donít know if this means that the 4A-GE has sequential fuel injection or not. Using this would be the simplest method of getting the ignition working. I could use the distributor unmodified and send the Ne signal to the Megasquirt. The Megasquirt would use this to determine engine RPM and I would have it trigger the coil directly. Although this is the simplest, I would rather run without a distributor and use a wasted spark, coil on plug, or coil near plug ignition.

    2) The easiest and most common way to run a wasted spark with a Megasquirt is to use a crank trigger wheel like one from the Ford EDIS. Although I like the idea of not using a distributor I donít really want to mount a toothed wheel on the crank pulley and a sensor nearby. And whatís the point of having a Toyota if youíre going to put Ford parts on it? I have also read that the Ford EDIS does have its limitations and the Megasquirt doesnít have full control over it. This is somewhat of a moot point now that Megasquirt has evolved a bit in that all that is needed from the Ford system now is the crank wheel, the sensor, and the coils.

    3) I also have the distributor that is on the car now which is a Toyota ESA ignition system. It is a more advance system in terms of using the sensors to run a single coil distributor system. Again it has two wheels, a twenty four toothed wheel and a four toothed wheel. The twenty four toothed wheel provides the Ne signal. This is an improvement in that the ECU is sampling the engine RPM more often and as such able to make corrections to fuel injection and ignition more often (particularily the ignition timing in acceleration conditions). The four toothed wheel now provides the G signal. However on my unit the four toothed wheel has two G sensors, G1 and G2. This setup would work great with the Megasquirt in that the twenty four tooth would provide the RPM signal and the four tooth would provide the ignition triggers. With the Megasquirt only one of the G sensors need to be wired up. Both can be wired together, but this is just inviting noise into the system. Now if I wanted to run a wasted spark system and/or coil on plug I would have to modify this distributor a bit. There are two ways I can do this, both involve grinding teeth off the four tooth wheel. I could remove two or three of the teeth. If I remove two I would have to remove two that are opposite of each other and I have to make sure that one of the remaining teeth lined up properly with the sensor to indicate TDC of cylinder one. Because the camshaft rotates at half the crankshaft speed the sensor would indicate a signal once for every crankshaft revolution. If I were to grind off three teeth then the Megasquirt would decode a single camshaft revolution. This might work better for coil on plug as a G signal would only be sent when cylinder 1 is at TDC. Alternatively I could connect the two G sensors in parallel and I would get a signal similar to the removing two teeth method.

    4) My last option, and likely the one I will use is to use the cam position sensor that came with the AE101 4A-GZE I have. This works very similarily to the ESA distributor in that it has two wheels, one with twenty four teeth. The other wheel however only has one tooth. I have not yet pulled mine apart but base on pictures Iíve seen it isnít just a small tooth, but rather a tooth that covers 180 degrees of the shaft. Because the VR sensors only trigger on the edges of the tooth then this isnít a problem. This unit also has two G sensors in it. The instructions on the Megasquirt Extra page state that the second sensor should be connected for wasted spark and not connected for coil on plug. However digging through the forums the concensus seems to be that the second sensor need not be connected at all. Considering that the Megasquirt will be counting the teeth on both wheels it should know how many teeth on the twenty four tooth wheel it should count before the next ignition event.

    Now option 4 is the favourite so far. Not only does it require zero physical modification it also comes in a neat little package. There are no connectors for spark plug wires and it will gain a little bit of clearance in the engine by (MR2s need all they can get). Instead of the large plastic distributor cover it has a slim aluminum cover. The only disadvantage I can think of would be replacing parts when they wear out. Because this engine was never offered as an option here in Canada parts might be a little difficult to source. Assuming that it uses the same bearing and shaft as the distributor (it bolts right up so why wouldnít it) then getting parts to stop future oil leaks shouldnít be a problem. I donít know how similar the sensors themselves are to those in the distributors, but they might be interchangeable. Also the 7M-GTE engines used a wasted spark ignition with a cam angle sensor. The housings are different but there is a chance that the inner components might be similar enough to be swapped.

    I should mention that the Megasquirt comes with the ability to accept one VR sensor input. I have ordered the Zeal Engineering Daughterboard which will give me two more VR sensor inputs (though I will only use one) as well as a 12V tachometer output and a few more on/off outputs. The 12V tachometer output can be modified to run the stock tach in the car. I was planning on using one of the on board outputs as a tach signal for the rev counter in the car. There is a relay coil modification listed on the Megasquirt site that describes how to do this (see below for diagram). Alternatively this signal could be used to drive an aftermarket tach. However the only way I would put an aftermarket tach in my car is if I mounted it in the dash where the stock one is. That would be more work than I think its worth. Itís a matter of personal taste, but I do not like the look of aftermarket tachs mounted on the dash or hanging from the A-pillar. Mind you this only applies if the vehicle already has a stock useful tach. If the car didnít have a tach or the engine has been swapped/modded to run drastically higher revs then I donít mind. Although in that case the old tach wouldnít be of much use so I would remove it and try to put the new tach in its place. Still I would prefer to find a model of the car at the wreckers that has an instrument cluster with a tach option and swap that in. Again itís just personal taste. Do what you want with your own car.

    Iíve already mentioned a few options of driving the spark plugs. I will expand on that a bit now.

    To understand how the spark plugs are fired a few basic electronic principles are needed to be understood. First there is the sensor which either tells the ECU when to fire the coil or, on older cars, fires the coil itself. The sensors in all my distributors/cam position detector are all Variable Reluctance (VR) sensors. It uses magnetic properties to detect the teeth. These only work when the toothed wheel is moving. The next step up is the Hall sensor. These are similar but they actively supply information even when there is no motion. Finally there are optical sensors. These act like the laser beams in movies where things are stolen from highly secure locations. When the beam is broken the alarm goes off. However in this case when the beam is broken a signal is sent to the ECU. A wheel with holes in it is rotated with a light source shining through the holes. On the other side a light sensor picks up the light. When the beam is broken it is like a tooth passing by a VR or Hall sensor.

    The coil is simple, it is a transformer. A simple transformer works with two coils (or windings) of wire. If the coils in a transformer are the same (have the same number of windings) and an AC voltage is applied to one coil (the primary coil), the same AC voltage can be measured on the other coil (the secondary coil). (This is often used as a DC filter and as an isolation technique in signal circuits). What is happening is the primary coil is creating a magnetic field with alternating current. This field induces a current in the secondary coil. Interesting things start to happen when two different coils are used. Most people these days have charged a cell phone. The cell phone charger has a transformer in it that ďsteps downĒ the voltage from 120V to something much smaller that the phone can use. This is accomplished but having a much smaller secondary coil than the primary. (Yes I know that charging circuits have more parts, Iíve built a few, Iím just trying to keep it simple). The exact opposite happens if you have a larger secondary coil than the primary (the voltage is ďstepped upĒ). This is how the ignition coil in the car takes twelve volts and creates a spark of tens of thousands of volts.

    But a carís electrical system is DC, not AC and transformers donít work with DC. So how is the coil fired? Well one end of the secondary coil is connected to ground and the other to a spark plug or distributor. The primary coil is connected to twelve volts on one side and ground on the other. The ground side is connected to ground through some kind of switching mechanism. This switching mechanism is used to ďbreakĒ the circuit. When this happens the primary coilís magnetic field collapse very quickly. This rapid change in magnetic field around the secondary coil induces a very high voltage current. The secondary coil sends this voltage to either a plug or distributor.

    The switching mechanism on older cars are physical switches driven by a cam in the distributor. This is what is called a points system. Because this is entirely mechanical the parts would wear out and need to be replaced as part of regular maintenance. The next step was to remove the points and use position sensors to activate a switching transistor. This is the basis of electronic ignition control modules. As cars became ďsmarterĒ more control was excersized over spark timing. Instead of simply triggering the coil the sensors would send the signal to the ECU which would then use switching transistors to trigger the coil. For the most part these transistors are located in the engine bay in a protective case (usually aluminum for heat sinking) near the coil. Auto manufacturers call them ignitors. Bear in mind that this is an over simplified explanation as most ignitors have some more components in them to protect the ECU from voltage spikes and some filtering.

    A wasted spark system does away with the distributor all together. It uses engine position and speed to determine when to fire a coil. It also uses one coil for every two cylinders. It is wired a little differently in that instead of the secondary being wired to the distributor on one end and engine ground on the other, each end is wired to a spark plug. When the coil is triggered the circuit is completed by the current travelling down one of the plug wires, arcing the plug, into the cylinder head, arcing the other plug and returning to the coil to complete the circuit. The term wasted spark comes from the fact that only one of the two cylinders is actually starting its power stroke and will ignite the air fuel mixture. The other cylinder being fired is just finishing its exhaust stroke and as such the spark will do nothing for/to it. One of the big advantages here is that there are no longer distributor caps and rotors to replace. Spark can be stronger as well because there no longer is a gap for it to jump from rotor to distributor cap. Each coil only fires half as often as a single coil/distributor set up. And finally the ECUís control over spark timing is no longer limited to what works in the range of the rotor alignment in the distributor cap. This is better for high revving engines. These are fairly simple to wire up as they only require two wires to the coil (12V and switching ground). However, if one of the two spark plug wires come off, you will loose both spark plugs.

    The next step is the coil near plug applications. I believe that some Chevrolet high performance engines use this set up. This uses one coil per cylinder with a short spark plug wire to the plug. There are some different coils out there that can be used with this. The simplest has three wire (not including the spark plug wire) connections. One wire connects to 12V, one to the control circuit and one to the cylinder head ground. As with a single coil setup the ground wire is connected to the secondary coil and completes the circuit with the spark plug. There are also four and five wire coils. These usually have the igniters built in and can be driven with lower input voltages. For example a four wire coil would have a 12V in to the primary coil, a 5V switching signal fom the ECU, A ground to the engine on the secondary, and a signal ground to the ECU. The megasquirt can control up to six ignition outputs, so each cylinder can be driven individually on a four banger. Alternatively two ignition outputs can be wired to four drivers (two drivers each) to run the coil near plug in a wasted spark configuration.

    Finally there is the coil on plug setup. These are usually wired similarily to the coil near plug, but do not have a spark plug wire going to the plug. Instead the unit itself plugs onto the spark plug. Like the coil near plug this can be wired to run in wasted spark or individually triggered. The advantage here is that there are no plug wires to wear out. Thatís about the only advantage I can think of. They would be closer to the engine heat and have to put up with more vibration. However, there certainly is a ďcool factorĒ in running coil on plug.

    My plan is to use the camshaft position sensor from my AE101 4A-GZE and I will probably use the stock wasted spark coils from that engine as well. The coils arenít very large so I will be keeping my eye open when I next visit the wreckers for something a little more powerful. The transistor drivers for the Megasquirt are actually Bosch units that have been used by auto manufacturers for years. The Megasquirt information online states that if using more than two a new connector should be put on the box as the traces on the board just arenít up to handling the power. I plan on not mounting the transistors in the box at all. Instead I will mount them on a heavy duty heat sink and put them in the engine bay somewhere (in a weather proof container of course). This should keep dangerous currents out of the MS ECU and keep the ECU box temperatures down a bit too. Iíve been thinking that I would like to try and do a coil near spark individually fired system. The advantages being longer spark times possible and each coil is only fired a quarter as many times as the stock coil and dizzy. However thinking about it I believe that a coil on plug set up might be better. I came to this conclusion after thinking about running the plug wires and mounting the coils. First off the most logical place to mount the coils would be on the side of the engine facing the front of the car. This puts them right above the exhaust and thus trying to keep them cool might be an issue. The next thought would be off the engine but near the fire wall. Again it would be near the exhaust. Not to mention that I donít think I would like the way that the plug wires would look coming over the exhaust cam cover. The coil on plug would look a lot neater. And if I could find some small enough to fit between the sides of the head I could even cover them all with a plate for a very clean looking upper part of the engine. But I am getting ahead of myself.

    What I will likely do is start by using the cam position sensor and the stock coils. Once I have that up and running I will start looking for some coil on plug units. I will then connect those up essentially the same way as the wasted spark coils and get that running. Because the spark outputs should be the same it should be straight forward. Then I will connect another set of drivers and get the individually firing coil on plugs working.

    General Purpose Inputs and Outputs

    The Megasquirt has eight user configurable inputs/outputs. At first glance this looks great, however it isnít quite that straight forward.

    First off these inputs/outputs get used for different features one might use. So depending on what the Megasquirt does for your engine determines how many outputs you can use. For example, the ignition outputs for a four cylinder wasted spark system requires two connections, one at D14 and one at D16 (these were originally the injection and acceleration indicator LEDs). If I were using the stock coil and distributor I would be able to use the purpose built on board ignition driver and still have D15 and D15 configurable in the Tuner Studio Output Port Settings.

    The options in tuner studio allow you to set seven outputs. They are labelled PM2 Ė Fidle, PM3 Ė Injection LED, PM4 Ė Accel LED, PM5 Ė Warmup LED, PT6 Ė IAC1, PT7 Ė IAC2, and PA0 Ė Knock Enable. Each output can be enabled or disabled and be set to a power on and trigger value of 0 or 1. It sounds complicated but itís not. Power on value determines whether the output is 0 or 5 volts when the MS is first turned on before any conditions are applied. So lets pretend it is turning on an LED once the RPM rises above 5000. If power on is set to 0, then when the key is turned to the on position the LED would be off until the RPM is above 5000. If the power on is set to 1, then the LED would be on when the key is first turned for as long as it takes the MS to figure out that the RPM is below 5000. In my case I will set this to 0. The triggered value is the logic output. Lets take the same example with the LED coming on above 5000 RPM. Setting the triggered value to 1 activates the LED just as expected. Setting it to 0 would ďinvert the logicĒ making the LED come on until the RPM rose above 5000 where it would turn off.

    Now the conditions for the port to activate can be set. The port can come on with one or two conditions. With one condition it is simple. For example: when coolant temperature is higher than XX turn on the radiator fan. Setting two conditions is pretty simple too. There is the option for using AND or OR logic. If two conditions are set with an AND then both conditions must be met before the output is activated. For example: When coolant temperature is higher than XX and RPM is higher than YYYY, turn on the fan. The other combination is the OR. In this case only one of the conditions must be met and the output will activate.

    Also hysteresis must be set. This tells the MS the amount that a variable must change before the output can be reset. For example, letís consider a fan that is turned on when the coolant temperature is above 50 degrees. So the engine is started cold and driven. The temperature rises to 50. As soon as it is higher than 50 the fan comes on. Now if the fan is good enough to cool the coolant almost instantly to 49 degrees the MS will turn off the fan again. If the engine is producing enough heat to instantly get it back up to 50 then the fan would come on again and the cycle would continue with the fan rapidly being switched on and off. But if a hysteresis of 5 degrees is set then the fan would come on once the coolant is above fifty and stay on until the coolant drops to 45 degrees.

    Now in my application I had to decide which outputs I would use. First I had to go through and figure out what I needed to connect. This is what I came up with:

    PT6 and PT7 are unavailable to me because I will be using the MSIIís stepper motor idle air control. So right there I lose two of my outputs.

    PM3 and PM4 are used as ignition outputs for my wasted spark set up. So there goes another two.

    PM2 will be configured as my tachometer output. The stock tachometer in the car is set up for a single coil system and will not work with the wasted spark setup. Even getting this to work will require a circuit and some experimentation. The following is a circuit diagram from the MS-II extra webpage, I am told it will drive the stock tachometer:



    That leaves me with two outputs: PM5 and PAO. It is important to note that if I were to go with and individual coil for each cylinder and not waste spark, I would lose these two outputs.

    So what am I going to use these for? Well I donít currently know if I will need both of them. I need to find out if the stock ECU is responsible for turning on the radiator fan or if it is on itís individual circuit. If it is on its own circuit then I will only need one output. If it is controlled by the ECU then I will have to wire up a transistor to drive a relay to turn the fan on when the coolant temperature is above a certain level. Not wanting to have a feature that I donít use, I will probably mount an LED in the dash to indicate a condition from the Megasquirt if I donít need the fan control. The two conditions that come immediately to mind are WARMUP and KNOCK. I plan to use the coolant temperature based rev limiter function and having an LED next to the water temperature gauge would be a good indicator that the driver shouldnít push the car as it is still cold. The knock indicator would be more useful when I swap the supercharger for a turbocharger and am experimenting with boost levels. Of course once the supercharger is removed I could run both as I wonít need the other output:

    The other output is for the supercharger. The supercharger is one of those things that make it harder to install an aftermarket ECU. Many people have put a switch in the cabin of the car so they can turn the supercharger on and off Mad Max style, but this isnít the greatest setup in my opinion. One would think that fuel economy would increase with the charger off, but then you are running a weak lower compression engine that has to work harder (use more fuel) to accelerate even a little. Leaving it on all the time is also inefficient as it takes a fair bit of power from the engine to rotate so that would equal an increased load during idle.

    So I plan to set up the PA0 output to give a five volt output when the manifold absolute pressure (engine load) reaches a certain value OR the throttle opened a certain amount. It will require some adjusting while driving the car to find the correct point to have the supercharger come on. The idea is that when cruising at part throttle and the road starts to go slightly up hill the load on the engine is increased and then the supercharger is engaged to give the car the power needed to maintain speed on a hill at part throttle. The other condition is simply when I want the car to go faster I press the pedal. If I press hard enough then the ECU engages the supercharger to give me the power I want/need.

    The obvious issue here is shifting. If Iím trying to accelerate quickly I will put my foot to the floor. When it comes time to change gears I will press in the clutch, release the accelerator, shift, release the clutch and press the accelerator again. When the clutch is in and my foot is off the gas the engine has no load and the throttle position is closed. The Megasquirt will take this information and determine that the supercharger should be off. Then when Iím in the next gear it will switch back on again. This is a little harder on the components and can affect acceleration times.

    Toyota addressed this issue by having a supercharger disengagement delay. This means that when the conditions are met to turn the supercharger off it will still wait a few seconds (I think I read somewhere that it is three seconds) before actually turning off the supercharger. So I designed a circuit to mimic this behaviour. I went through a couple of prototypes until I came to what I think is the most efficient answer. The circuit is made up of six components: Two diodes, a resistor, a capacitor, a darlington transistor, and a relay:



    And here is the prototype I built as a proof of concept:


    Without getting too technical the darlington is set up as an on/off switch which is turned on by the five volt output from the Megasquirt. When it is turned on it activates the relay which in turn activates the super charger. The darling ton Iím using is the TIP122. It has a built in resistor from the base to the emitter. With this in mind I built a simple rc circuit as a time delay. The on signal is fed through a current limiting resistor before entering the base of the transistor. Prior to this resistor is a capacitor connected to ground. When the Megasquirt sends this output high, the transistor switches to its ďonĒ state and the capacitor charges. When the Megasquirt switches this output low again the circuit remains active for as long as it takes the capacitor to discharge. In order to make sure that the capacitor does not discharge back into the Megasquirt a diode is placed between this circuit and the MS output. The last diode is used as a quenching diode on the relay to protect the circuitry from voltage spikes cause by the sudden collapse of the electromagnetic field when the relay is turned off. A resistor value of 27k and a capacitor valued at 470uF gave me a two and a half to three second delay on my prototype on the bench.

    The reason to use the darlington instead of a standard transistor is that a standard transistor would discharge the capacitor more quickly.

    Since this circuit is so simple it would be pretty easy to put all of it (minus the relay) in the proto area of the MS. This way only one wire on the DB37 connector need be used to drive the relay that turns on the supercharger.

    Wll that's all I have for now. I am still waiting for my stuff to arrive in the mail. Once some of the parts actually show up I will take more pictures.

    If anyone has any questions, comments, suggestions, tips, or want's to tell me I'm wrong on something, please do. I only ask that you are polite about it.

    Cheers,
    Berg
    Last edited by Berg; 03-18-2010 at 07:01 PM.

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    "If a man tries to fail and succeeds, which did he do?"
    I ENCOURAGE EVERYONE TO HAVE A FIRE EXTINGUISHER IN THEIR CAR
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    My Megasquirt project:
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  2. #2
    Lifetime Member joe's gt is a glorious beacon of light joe's gt is a glorious beacon of light joe's gt is a glorious beacon of light joe's gt is a glorious beacon of light joe's gt is a glorious beacon of light joe's gt's Avatar
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    Berg, you gonna tune it yourself?
    - Shadow's Minion Army - Grand Inquisitor -

    This has been the best and most frustrating experience of my life. I thank my dad for all the help he has given me in this rare restoration. Now that the car is done, I wouldn't trade it for the world.

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  3. #3
    I let PearlJammzz run The Dragon in 14.7 andy is a name known to all andy is a name known to all andy is a name known to all andy is a name known to all andy is a name known to all andy is a name known to all andy's Avatar
    andy has been to an annual Dragon Meet! andy helped get Grayscale's Celica towed from The Dragon in 2008. andy helped get Play's clutch job done. andy helped Azzy get to The Dragon in 2009.

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    Can I have yur 4agze dizzy? I'll trade you a usdm one! Nah but very good job there

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    Shadow's Minion Army - member #2

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    Originally Posted by vafalla
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    No, I'm still gay. I like the ladies too.

  4. #4

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    I would like to, but as of right now I don't have any experience. I have to read up on tuning quite a bit before I try it. There isn't much around here in terms of accessable dynos. Off the top of my head I can only think of one and they are expensive and don't like imports. However there is a whole bunch of information on tuning the Megasquirt online. I'll be spending much time going over that.

    Cheers,
    Berg

    Quote Originally Posted by andy View Post
    Can I have yur 4agze dizzy? I'll trade you a usdm one! Nah but very good job there
    I'd like to keep one of each, just in case. I'll be making frequent trips to the wreckers in the comming months, I'll keep my eyes open for one for you (though these are fairly rare in my neck of the woods).

    Cheers,
    Berg

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  5. #5
    Murg's Heathen's Pet Snitch Monkey CollapsedNut is a splendid one to behold CollapsedNut is a splendid one to behold CollapsedNut is a splendid one to behold CollapsedNut is a splendid one to behold CollapsedNut is a splendid one to behold CollapsedNut is a splendid one to behold CollapsedNut is a splendid one to behold CollapsedNut's Avatar
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    Holy technical write up Batman

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    Originally Posted by manda
    what do I know? I'm just a woman on a car forum..
    guess I better get back to makin your sammich
    Cheese! Cheese for everyone! Wait..no. No cheese for you!

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  6. #6

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    Quote Originally Posted by CollapsedNut View Post
    Holy technical write up Batman
    Just trying to make sure I understand what's going on.

    Cheers,
    Berg

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  7. #7
    Senior Member DudeMan will become famous soon enough DudeMan's Avatar

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    Cliffs?

  8. #8

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    Quote Originally Posted by DudeMan View Post
    Cliffs?
    Putting in a megasquirt.
    Figuring out what I need to make stuff work.
    Think I got a big portion of it figured.

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  9. #9
    Lifetime Member joe's gt is a glorious beacon of light joe's gt is a glorious beacon of light joe's gt is a glorious beacon of light joe's gt is a glorious beacon of light joe's gt is a glorious beacon of light joe's gt's Avatar
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    Quote Originally Posted by Berg View Post
    I would like to, but as of right now I don't have any experience. I have to read up on tuning quite a bit before I try it. There isn't much around here in terms of accessable dynos. Off the top of my head I can only think of one and they are expensive and don't like imports. However there is a whole bunch of information on tuning the Megasquirt online. I'll be spending much time going over that.
    Cheers,
    Berg
    Yeah, its a risk, but its also a black art and no one likes to share information on it. So I hope you end up trying it out. You easily have enough knowledge to try it out. Jeff Hartman's book and the tuning tips section of the efi101 forum have a great info in addition to the megasquirt site. Good luck man.
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    Thanks! I'll definately be doing a lot of reading on the subject. The megasquirt will not be installed in the car until I have the wideband O2 sensor and gauge is installed. It will definately be an adventure. I'll keep posting as things develope.

    Cheers,
    Berg

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  11. #11

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    A word on sensors

    In order for the ECU to inject the proper amount of fuel, it needs to know a few things about how the engine is behaving. It achieves this by using several sensors to determine what the engine is doing. I already mentioned RPM measurements when I was talking about the ignition system.

    Throttle Position Sensor (TPS)

    The TPS is actually a fairly simple device. It is a potentiometer. Usually the TPS will have a three wire connection. A potentiometer has three connections. Think of it as an electronic resistor. There is a connection at either end and one in the middle. Measuring the resistance from one end to the other would give the maximum resistance value. The middle connection is on an arm that can be moved from on end to the other. When the arm is moved to one end and the resistance is measured from that end to the arm is will give a value of near zero (a short). If the arm is then moved to the other end and the measurement is taken again then the value would read maximum resistance. If a voltage is applied to one end and a voltage measurement made on the arm it would change depending on where the arm is (how much resistance is applied). So if ten volts is applied at one end, the measurement will read ten volts when the arm is at that end and decreases as the arm is moved to the other end. This is essentially what the ECU is doing with the TPS. One end is tied to ground, the other has a reference voltage (Vref) applied to it. In the case of MS this Vref=5Volts. The last connection is called the TPS signal. This is simply a voltage reading that will vary from a less than 5 to 5 volts depending on throttle position. (I say less than five volts because not all TPS will give a reading of 0 volts because the arm doesnít always travel all the way to the ground connection, similarily the arm doesnít always go all the way to the Vref). Different car manufactures wire the TPS differently. Some have a TPS signal equal to Vref at closed throttle position and some have the TPS signal equal to Vref at Wide Open Throttle (WOT). One thing that should be true for all TPS systems is that the TPS voltage signal should increase/decrease linearly across the entire range of motion. This works well for the MS because it calibrates the TPS signal by measuring the Vref at closed throttle and again at WOT. It then interpolates between the two to determine how far open the throttle is for any given TPS signal.

    Coolant Temperature (CLT) Sensor

    For an engine to work at its peak efficiency it needs to be warmed up. The ECU needs to know if the engine is warm or not. If the engine is not then warmup enrichment is applied and the ignition timing is adjusted for the sole purpose of warming up the engine faster. A good way to measure how an engine is doing temperature wise is to measure the temperature of the coolant. The sensor used is very simple. It is simply a temperature dependant variable resistor or thermistor. When the temperature is -20 degrees it has a resistance of XX and when it is 30 degrees it has a resistance of YY. Thatís pretty much it. There are two main variations of this sensor, a one wire and a two wire. The one wire (like the ones that come with autometer gauges) connect that one wire to the device reading the temperature (gauge, ECU) and then the circuit is completed by the sensors physical connection to the metal of the engine as a ground. The two wire sensors donít rely on the engine ground and use the second wire as a ground returned to the device reading the temperature to complete the circuit. These sensors are said to be better as they are independent of all the other systems that use the engine as a ground. The MS comes pre-calibrated for a specific GM coolant temperature sensor. It can be recalibrated to other stock sensors but I plan on just using a new GM unit. I have several locations I can install the sensor into. There is the stock ECU sensor, the cold start sensor/switch (MS doesnít use a cold start injector but instead increases the amount of fuel injected by the main injectors), a couple of temperature dependant vacuum switches (for devices like the EGR which has already been removed), etc. This is one of the ways an aftermarket ECU can help clean up the engine bay. Many of the coolant temperature sensors are for pollution control which is usually removed with a new ECU.

    Intake Air Temperature (IAC) Sensor

    As most people already know injecting the correct amount of fuel into an engine requires that the amount of oxygen in the engine that is available for combustion be known. This is determined with a couple of sensors. One is the IAC Sensor. The temperature of the air determines how dense it is. The density of the air directly relates to how much oxygen there is in a particular volume. The colder the air is the more oxygen there is to burn. The more oxygen there is the more fuel can be injected and the more power can be produced. If the air is hotter then it can not burn as much fuel so less fuel has to be injected to maintain the proper Air Fuel Ratio (AFR). This is why the ECU needs to know the temperature of the air entering the engine. The sensor itself operates exactly the same as the CLT Sensor. The difference being that it isnít installed in the coolant. The MS is again set up for a GM sensor. This sensor is an ďopen elementĒ sensor in that the actual material that measures the temperature is exposed to the air. This is the sensor I plan to use. It has been said that these sensors are somewhat fragile so some people use oxygen sensor safe silicon on them to hold the element in place. What I havenít yet decided on is where I will mount this sensor. The recommended place is just before the throttle body on the intake. I was considering placing it where the cold start injector is now as a convienant way to plug up that hole, but have read that the vibrations and heat from the engine would cause it to wear out quickly. On naturally aspirated engines it doesnít really have to be placed in the intake track at all, just near where the air is sucked in. On forced induction engines it is better to place it nearer the intake manifold (after the intercooler) to account for the temperature increase caused by compressing the air. The stock IAT sensor on my car is located in the Mass Airflow (MAF) Sensor housing.

    Manifold Absolute Pressure (MAP) Sensor

    The MAP sensor is the other sensor that is used to determine how much air is entering the engine. The car came stock with a MAF sensor that has a ďdoorĒ or ďflapĒ in it. When the engine needs more air the difference in pressure would force this door open. The sensor itself is attached to this door and works very much in the same way as the TPS. There are many arguments on the internet as to whether the MAF or the MAP is a better system. The MAP is simpler in that it only requires a vacuum line connection to the intake manifold. However the MAF can be beneficial to certain engine modifications such as larger cams. Aggressive cams can fluctuate the pressure in the manifold causing a MAP equipped ECU to constantly be making corrections and thus create a poor idle. With a MAF system the air going in is automatically averaged over all the cylinders and so a smoother idle can be achieved. For the most part though, people who have MAF systems donít like them. Many claim that they are restrictive and thus ďchokeĒ some of the engines potential. They have more wires that one must deal with. And a problem that I have experienced, if there is a leak in the intake after the MAF that air is being sucked in (or blown out under boost) that isnít accounted for resulting in incorrect AFRs.

    MAP sensors have taken me a little time to get my head around, and Iím still not 100% confident that I fully understand them. I am used to having a boost/vacuum gauge in my car. When the engine is off this gauge reads zero. When the engine is started and there is no boost there is vacuum. This is where part of my understanding problems come from. ďOf courseĒ I think, the engine is sucking in air, there is going to be a vacuum. When the supercharger engages it creates boost and the gauge goes from the vacuum side to the psi above zero side. What I had to learn is that what the boost gauge is reading out is the Manifold RELATIVE Pressure, in that it is relative to the atmospheric pressure. So an engine boosting at 5psi has a MAP of 5psi above atmospheric pressure. MAP sensors do not give a ďbelow zeroĒ value. If a MAP sensor gives a value of zero then the manifold is in absolute vacuum. The only way this is ever going to happen is if your car is in space. When the throttle is closed the pressure in the manifold is decreased below atmospheric because the engine is sucking the air out of the manifold and the throttle is preventing more from getting in. When the throttle is opened the pressure in the manifold increase toward the atmospheric pressure value. When the engine is at WOT the pressure in the manifold is near atmospheric (on a naturally aspirated engine). It will be a little less than atmospheric just because the engine moving air out of the manifold. On a forced induction setup the pressure in the manifold actually increases above the atmospheric pressure.

    When I purchased my MS I ordered a MAP upgrade kit. This kit has a MAP that is capable of reading a higher boost level than the original one. Considering that I am planning to eventually switch to a turbo and that I currently do not know how much boost I will be able to make I wanted to cover all my bases. The kit comes with a second MAP sensor on the board for barometric corrections. The MS compares the value of the MAP to atmospheric pressure to determine the engine load. With the stock setup the MS can be told not to do that or to take the MAP reading when the car is turned on but not started as the atmospheric value. This usually works fine, but if one were to drive up a mountain (like the ones an hourís drive west of where I live) the atmospheric pressure would change significantly from bottom to top. Having a second sensor open to the air provides the ability to make real time corrections. It isnít essential by any means, but I think its useful.

    In the tuning software the MAP value is used on the y-axis of the tuning tables. Older versions of the software actually displayed the kPa value. However, newer versions have done away with that and replaced the kPa with fuelload %. This is a representation of MAP. Unfortunately I do not yet know how to use these values. For example, does 100% fuel load equal atmospheric pressure? Does that mean that I have to input values above 100% for under boost conditions? Or can I adjust the fuel load values such that 100% is above maximum boost conditions? I am still trying to find these answers.

    Exhaust Gas Oxygen (EGO or O2) Sensor

    This is a sensor that is placed in the exhaust system of the engine. It really doesnít do much in terms of adjusting the amount of fuel injected into the engine. This surprised me a little. However considering that the O2 sensor wire broke on one of my Celicaís and I didnít notice a change in driving (other than the check engine light being on) I can believe it. The O2 sensor is instead used to make corrections. The MS allows the user to set how much priority it has to fuel injection. I believe the recommended value is around 7%.

    The EGO sensor is used to provide feedback as to how much oxygen remains unburnt in the exhaust. The MS tuning software has an AFR table in it that has looks like the other tables (has fuelload% on the y axis and RPM on the x) but the values in the tables are targets for the EGO sensor reading. The MS then will try to adjust the amount of fuel injected to give the oxygen sensor the reading specified in the AFR table. It will only do this to a certain extent depending on how much priority you give it. It is even possible to run without an O2 sensor all together.

    There are two types of O2 sensors that the MS can use, narrowband and wideband. Narrowband is typically what vehicles are equipped with stock. The basic ones have a one wire setup. When the O2 sensor heats up it creates a voltage based on how much oxygen is in the exhaust. The one wire units are ignored until the engine has warmed enough to create the proper voltage in the EGO sensor. The next step up is a heated O2 sensor. This is the same as a one wire, but has three or four wires. On the three wire one wire is the sensor, one is ground for the heater, and one is power for the heater. The four wire is the same, but the sensor has a signal ground running to the ECU as well. All the heater does is make he EGO sensor reading valid sooner. The narrowband sensor will output a voltage between zero and one volt. Essentiall all it does is tell the ECU "lean" or "rich". That's it.

    The other type of sensor, the better one, is the wideband O2 sensor. These are typically more accurate that the narrowband. Instead of the varying 0-1 Volts that simply let the ECU know if it was lean or rich the wide bands use a broader voltage range and work with a linear scale. As such a specific voltage output translates to a specific AFR. With a wideband O2 sensor the MS can be trusted to make better corrections using the AFR lookup table. One of the things that I will be purchasing when it comes time to install the MS in my car is a wideband sensor and controller. They can be purchased from the same place I bought the MS and even offer a gauge that can be mounted in the dash for real time outputs. Everywhere I have researched state that tuning should not be done without a wideband EGO sensor.

    Again, if anyone wants to correct me, please do.

    Cheers,
    Berg

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  12. #12
    Ultimo Miembro FantŠstico Gigantesco ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD's Avatar
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    There's a good 5-6 dyno's in Calgary.

    But yes, the time is pricey. I had my 165 tuned at http://www.dynomotive.ca/ by Toma. His rate was very reasonable in comparison to some that I saw. I could get it sorta close by street tuning, however it is definitely a lot easier on the heart to have a professional do it. Plus you can see and hear a lot more that is going on with the dyno.

    Good luck! I know this has been a big project in the making for you.





    Quote Originally Posted by Berg View Post
    I would like to, but as of right now I don't have any experience. I have to read up on tuning quite a bit before I try it. There isn't much around here in terms of accessable dynos. Off the top of my head I can only think of one and they are expensive and don't like imports. However there is a whole bunch of information on tuning the Megasquirt online. I'll be spending much time going over that.

    Cheers,
    Berg
    1988 ST165 2.2L @ 370awhp
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  13. #13
    Lifetime Member joe's gt is a glorious beacon of light joe's gt is a glorious beacon of light joe's gt is a glorious beacon of light joe's gt is a glorious beacon of light joe's gt is a glorious beacon of light joe's gt's Avatar
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    Quote Originally Posted by ChrisD View Post
    There's a good 5-6 dyno's in Calgary.

    But yes, the time is pricey. I had my 165 tuned at http://www.dynomotive.ca/ by Toma. His rate was very reasonable in comparison to some that I saw. I could get it sorta close by street tuning, however it is definitely a lot easier on the heart to have a professional do it. Plus you can see and hear a lot more that is going on with the dyno.

    Good luck! I know this has been a big project in the making for you.


    Chris said it better than me. I think it would be awesome for you to do your own street tuning. But in all honesty, you should take it to a dyno after your done on the street to extract more and iron out any mistakes or things you may have missed.
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    This has been the best and most frustrating experience of my life. I thank my dad for all the help he has given me in this rare restoration. Now that the car is done, I wouldn't trade it for the world.

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  14. #14

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    For sure I absolutely agree. I didn't mean to imply that I wasn't going to a dyno. There is no possible way to get the best tune without using a dyno. I just meant that I am planning to try and get it tuned to the best of my ability on the street before taking that step.

    Thanks for the replies guys. My MS is still sitting in customs according to the tracking information. I'll keep this thread updated as things develope. Hopefully I get the details right.

    Cheers,
    Berg

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  15. #15
    I let PearlJammzz run The Dragon in 14.7 andy is a name known to all andy is a name known to all andy is a name known to all andy is a name known to all andy is a name known to all andy is a name known to all andy's Avatar
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    fyi, the JDM 4age map sensor dizzy is a 24 tooth bottom and a 4 tooth top

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    Shadow's Minion Army - member #2

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    Originally Posted by vafalla
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    No, I'm still gay. I like the ladies too.

  16. #16

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    Quote Originally Posted by andy View Post
    fyi, the JDM 4age map sensor dizzy is a 24 tooth bottom and a 4 tooth top

    So they use the Toyota ESA ignition system. That's good to know, it would work well for a MS setup.

    Cheers,
    Berg

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  17. #17

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    Quote Originally Posted by Berg View Post
    In the tuning software the MAP value is used on the y-axis of the tuning tables. Older versions of the software actually displayed the kPa value. However, newer versions have done away with that and replaced the kPa with fuelload %. This is a representation of MAP. Unfortunately I do not yet know how to use these values. For example, does 100% fuel load equal atmospheric pressure? Does that mean that I have to input values above 100% for under boost conditions? Or can I adjust the fuel load values such that 100% is above maximum boost conditions? I am still trying to find these answers.

    The software has simply relabled the kPa as fuelload %. The numbers themselves are still exactly the same. So if I were t enter a value of 100% fuelload it would simply mean 100kPa.

    Tracking still says that the MS is in customs, I guess I wont get to play with it this weekend.



    Quote Originally Posted by ChrisD View Post
    There's a good 5-6 dyno's in Calgary.

    But yes, the time is pricey. I had my 165 tuned at http://www.dynomotive.ca/ by Toma. His rate was very reasonable in comparison to some that I saw. I could get it sorta close by street tuning, however it is definitely a lot easier on the heart to have a professional do it. Plus you can see and hear a lot more that is going on with the dyno.

    Good luck! I know this has been a big project in the making for you.


    I checked out the dynomotive website. $75 for a baseline, $100/hr for me to tune and $150 for them to tune. I admit I'm kind of tempted to take the car down to get a baseline before I swap the ecu, just to see what kind of difference can be made.

    Cheers,
    Berg
    Last edited by Berg; 03-19-2010 at 04:08 PM.

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  18. #18
    Ultimo Miembro FantŠstico Gigantesco ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD has much to be proud of ChrisD's Avatar
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    Cool. Toma's a bit less formal than the site, chances are he'll cut ya a deal on the tuning - the shop is just something he does in his spare time for fun, he has a day job too. I believe he charged me for like 2 hours and we were there tuning for about 4.

    The only downside is that it is a dyno dynamics dyno, so it's a bit hard to compare to the typically posted dynojet's on the 'net.

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  19. #19

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    Hmm... the site advertises that they have two dynos now. I admit I do not know much about different kinds of dynos. A quick google has me reading that the mustang dyno is a true measure of torque and can load the car to simulate the work the engine has to do to move the car around. I now have another thing to look up

    Cheers,
    Berg

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  20. #20

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    Just a note, I was wrong in stating the MS-II can't do sequential fuel injection. So long as one uses the MS2 Extra firmware and Tuner Studio the unit can be expanded with various daughter boards from jbperf.com. The site also has an I/O extender board to increase the number of inputs and outputs. This board requires either some modification to the MS or to be mounte in its own case. It communicates using a CAN bus serial connection. The inputs and outputs can't be used for everything because of timing issues with the CAN bus (so injectors and ignition is out). However things where timing is less critical, like boost control, launch control, fans, etc would work. I don't need any of these for my installation but its worth a look to see what they can do. There is a youtube video of someone who used this board to bring in data from an accelerometer for data logging g-forces. It's not in a car (just on the bench) but it seems to work.

    Cheers,
    Berg

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  21. #21

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    Well I figure I’m overdue for an update.

    The Megasquirt arrived in a box last Monday. Well they tried to deliver it, but I wasn’t home. So I had to wait until Tuesday after work to go and pick it up from the local post office. My first thought when I picked it up was that it was too small and that there was no way that everything I ordered was in there. I didn’t open the box until the next evening when I finally had a chance to work on it. I decided to put it together in my office after hours as I have better equipment for soldering there and there is no cat to “help” locate components.

    This is what was in the box:



    I started by assembling the JimStim. This is the device that simulates some of the engine’s signals for testing purposes to ensure that the MS is working before installing in a car. I followed the instructions here:

    http://jbperf.com/JimStim/JimStim_v1_4_assembly.html

    My JimStim had a few differences than the one on the site above. Nothing too difficult to figure out though. The voltage regulator is rotated ninety degrees anticlockwise and folded down to fit against the board. There is also a polyfuse added for protection (this is a good thing). I assembled the Jimstim and it tested fine.



    Next it was time to assemble the MS. There are plenty of instructions online for putting this thing together. I followed these two:

    http://www.megamanual.com/ms2/V3assemble.htm#power

    http://www.msextra.com/doc/ms2extra/build_manual.htm

    The first link above is a very good step by step assembly with testing along the way to make sure things are working properly as you go. The second one has you install everything and then test. If there are any problems then with the second method you have to check everything as opposed to knowing where the problem occurred. What I did was write down all the modifications that the msextra instructions called for and then went through the megamanual instructions and write them in there. So I made my own set of instructions that were a combination of the two. This worked well for me and I was able to put everything together and have it all work right away.

    First I checked the board for shorts and fitment as per the instructions and then assembled the power supply. At this point the Jimstim is plugged in to the connector and a multimetre is used to test both the twelve volts and five volt power supplies.



    The next part that was constructed was the RS232 serial interface. This is the communication between the MS and a computer. A serial cable is connected to the MS through an interface chip that translate commands between the computer and the MS processor. The first step is to make sure that the computer is talking to the serial port. This is done by shorting the Rx and Tx pins in the connector and then using hyperterminal to send characters to the Tx pin and receive them on the Rx pin. All received characters should appear on the hyperterminal screen. There are two pins on the processor which are used to communicate to the serial chip. Again these are Rx and Tx. These two pins are shorted for testing purposes. Once shorted the Jimstim is used to power the MS board (the serial chip is the only thing that requires power at this point in the build. The serial cable from the computer (in my case a USB to serial adapter) is plugged into the board. With the pins on the processor socket shorted characters in hyperterminal should go from being input on the keyboard, through the serial cable, through the chip on the board, to the Rx pin on the processor socket, to the Tx pin on the processor socket, back through the chip, back to the computer and displayed on the screen. If this works then computer-processor communication is possible.

    Next the processor is mounted and programmed with the firmware according to the instructions. Now the processor is capable of communicating with the computer, but nothing works for the inputs as that part hasn’t been built yet.



    This is how the assembly went, put a little together, test it, and continue. Most of the parts that the msextra stated to leave out were left out. The exception being R37 and R38. The megamanual states that these are clamping resistors used for protection. I do not know why the msextra says to leave them out and was unable to find an answer so I put them in. Should it cause problems later I can always remove them later. I also did not install all the circuits. I know that I will be using VR sensors for RPM inputs so I didn’t bother installing the Hall sensor circuit. I also didn’t install the ignition driver, or the Fidle circuit because I am planning on using wasted spark and a stepper motor for Idle speed control. Before long I had it all together. The average expected time to put it together is stated to be eight hours. It took me a lot less time than that, but as I said I didn’t put all the circuits in and I have a fair bit of experience putting boards together (it used to be my job).



    I then tested it with the Jimstim to make sure everything was working.



    Now that that was done, it was time to start doing the modifications to make it work with my setup. The first thing that I did was to install the jumper wires to run the Idle air control stepper motor and the second MAP sensor.



    Next I put the supercharger control circuit on the board. Half of the circuit is mounted on top of the board and the capacitor is mounted underneath. After testing I found that the 470uF cap didn’t hold it on long enough and I install a 1000uF (it was all I had on hand). The circuit now holds a relay on for almost exactly three seconds. Because I have no way to adjust the input to the MAP sensor right now I just set it up in the tuning software to activate the circuit at 60% throttle, which I can simulate with the stimulator. It works fine.







    Next task was to put together and install the Zeal Engineering daughter board. This board is designed to fit in the case lid of the MS. It has two VR conditioners and several outputs to drive relays and such. However these outputs just connect to the outputs on the board for the general input/outputs. This does not add any outputs, it just conditions the ones that are already there. For this reason I only installed one (I only have one output left). This output is connected to the “warmup” LED on the board and then configured in the software. For testing purposes I set this to turn on when the coolant temperature reaches 60 C. This simulates turning on a radiator fan. Again this worked first try. To test these outputs I’m connecting them to outputs on the DB37 connector and then jumping the corresponding pins on the JimStim to the LED pins. This way when an output is activated (goes low or is grounded) the LED on the JimStim turns on. In the case of the supercharger circuit I actually have a relay connected.





    Unfortunately this is where something went wrong. Nothing major. The Jimstim can simulate a dual wheel setup like the Nippon Denso cam sensor I’m planning to use, but not properly. The second tach signal is a square wave, which will not trigger the chip on the Zeal daughterboard. After discussing online with members of the msextra board I was told that a useable signal could be created by putting a small capacitor in series with the second tach signal. The next day I decided to do this. Somewhere during this procedure I must have shorted something. It was a stupid mistake as I was moving wires around while power was applied. All of a sudden the power LED on the Jimstim dimmed. I turned the power off and on again. Things worked alright for a few seconds then the LED dimmed again. When the LED dimmed the MS turned off. At first I thought I had damaged my MS. I unplugged the JimStim and powered that up by itself. The power supply showed a higher current draw and the voltage regulator on the JimStim quickly heated up. So did the chip that provides the tach signals. I removed this chip and then checked for shorts using this schematic: http://jbperf.com/JimStim/jimtim_v1_4_schem.png

    The board checked out fine and I reconnected it to power. It stayed cool and all the voltages checked out. I connected it to the MS and tested again. Everything worked but the tach signal (obviously, the chip was on the desk next to the board). I then checked the chip itself. Pin three is VDD and pin 4 is GND (power supply and ground). There were 21 ohms of resistance between the two. That’s pretty much a dead short. When the chip was plugged in it shorted the board and drew too much current from the power supply. This caused the polyfuse to heat up and open. Once it cooled down again it would close and heat up again. This is why the LED was dim and not off, the fuse was opening and closing quickly. Also I had the power supply current limited so it could pull a maximum of just less than an amp. So I have ordered a replacement chip and a spare and am waiting for those to arrive.

    Cheers,
    Berg
    Last edited by Berg; 03-31-2010 at 09:53 PM.

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  22. #22

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    On Saturday my girlfriend went to the garden show with one of her friends. I had the afternoon to myself. I took this opportunity to do one of my favourite things: wandering around the local Pick n Pull. Initially I was just looking for a set of coils that might be a little better than the ones that came with the AE101 4AGZE. I found a Pontiac that had a DIS module for a V6. It had three coils and the connector. I figured that I could take this and have two coils and a spare. So I cut the wires about four inches from the plug and removed the unit. I then decided to wander around the imports section looking for nothing in particular.

    Well as luck would have it there was a MkIII Supra there with the 7M-GTE engine. The turbo, exhaust manifold and intercooler were long gone, but the rest of the engine was there. I was only thinking of ignition so I removed the cam position sensor and the coils with the plug wires. The coils on this engine look exactly the same as the ones on the 4AGZE and I suspect that they probably share part numbers.



    After I took the coils off I was getting ready to leave the car when I thought that I should maybe take the injectors. I didn't know at the time if the injectors flowed more than my 4A-GZE ones but figured that for sure they wouldn't flow less, so worst case scenario they would just be spares for what I have. I looked it up after I got home and the 4A-GZE flow 365cc/min and the 7M-GTE flow 440cc/min. I cut the wires going to the injectors so I could wire them up and use the stock plugs. I need to find a place that will clean and test injectors to ensure that they are all good. Incidentally the gentleman at the register failed to charge me for them so thats a free injector upgrade! Well worth soaking my mechanix gloves in gas.



    In getting the injectors out I had to remove the throttle body first. The throttle body is much bigger than any of the ones that I have on any of my engines. I know that a 3S-GE throttle body will bolt right up to the 4A-G(Z)E engine no problem (I've done it), but I do not know if the same bolt pattern is shared with the 7M-GTE. If it is, or if the getting the 7M-GTE throttle to fit is simple then I will probably use that. If not I will use a 3S-GE throttle body.

    I started to play with the TPS of the 7M-GTE throttle body. It has four wires instead of three. As far as I can tell the two at either end of the connector are the ends of the potentiometer (as I described in an earlier post) and the one nearer what would have been the top of the throttle body is the connection to the arm. The extra connection only seems to indicate when the throttle is fully closed. I do not know if this had something to do with idle control on the Supra, but for my installation I will only need the three wires. I'm also assuming that TPS connections are similar across 80s era Toyotas so what I learn with this one will be relavent to any of the ones I have available to use.



    I then decided to play with the coil packs. The first thing I did was try and get it apart. Removing the connector was simply a case of unbolting it and pulling it off. The same with the coils. With the coils removed the mounting plate on the bottom also came off. Now I was left with the plastic shell with a metal cover where two of the coils were and a a metal back plate that was between the plastic and the mounting plate. It took quite a bit of time with small screwdrivers, a knife, and a scribe (dental pick) to get the plates off. Under these covers is the stock electronics for controlling the coils. This was covered by a protective goop that was a real pain to get off. After that I used the multimetre to determine which connector pin came into the case. I then cleaned everything up and mounted my coil drivers to the backplate to use it as a heatsink. Finally I connected the driver transitor through the old wiring of the case to the connector. It looks really good but until I can simulate a tach input I can't test them. Although I could try hooking up the Supra cam position sensor and spin it with a drill.... That would test both the VR conditioner circuit on the Zeal board and the ignition outputs...





    I'm still undecided on what to do with the connection for the third coild. One of the pins has a constant twelve volts on it so I cnt leave it exposed. I can't cut the baseplate off at two because one of the mounting bolts fits under the coil. I could cut the pins off and cover the exposed metal with silicon to prevent any probems. I'll have to explore my options.

    Feedback is always welcome!

    Cheers,
    Berg
    Last edited by Berg; 03-31-2010 at 11:38 PM.

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  23. #23

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    Well I am still waiting for the new chips for the JimStim to arrive, but everything else is lookig good. I spent some time going through the electrical schematics here: http://opc.mr2oc.com/

    I have managed to figure out a lot of the wiring I'm going to have to do from this information. Firstly the two fans (radiator and engine bay) are on their own circuits. The schematics include both models that have AC and those that don't (like mine). The circuits I am looking at are on the first two pages of this document: http://opc.mr2oc.com/online_parts_ca..._diagrams2.pdf.

    The first page has the Engine bay cooling fan circuit. It is an entirely self contained circuit. There are two external connections, one to the ECS and one to the speed sensor. The one to the ECS was only used in 1989 MR2s and the speed sensor was only used in 1988. Mine is a 1987 so the circuit stays completely independant.

    The second page has the radiator fan circuit on it. I do not have A/C on my car so not allof this circuit is present in my car. I have the shorting pin in place of the high pressure switch. This is a completely independant circuit and doesn't look to be connected to the ECU in any way.

    So I do not need the extra output to run a fan as described above. I could use it to run an extra fan. For example I could put a fan on the intercooler. However when the car is moving there isn't much point in having a fan running as it wouldn't be able keep up with the air entering the engine bay. I could set it up to only activate at a high intake temp and a no load (low MAP) condition. I dont think I will be going this route, this is just an example.

    The tenth and eleventh pages have the charging and starting circuits schematics displayed. The charging circuit is very simple and has no connections to the ECU. The starting circuit has one connection to the ECU and that is the cold start injector. For the most part the cold start injector is controlled by a temperature switch and the ECU has the ability to turn it on for a short time. Essentially all it does is inject a SMALL amount of fuel to aid in starting the engine only when the starter is engaged. Thats all it does. The MS doesn't use this as it just uses the main injectors and uses a cold/cranking enrichment. The MS also has a priming pulse which is designed to get rid of any air in the fuel lines. This pulse occurs before the engine is started but afterthe ECU is powered up.

    I also spent a fair bit of time looking at this: http://opc.mr2oc.com/online_parts_ca..._diagrams4.pdf. It's a little harder to read, but it has a lot more information. Figure 1 on page 3 has the radiator fan relays on it. Since I do not have A/C I don't know how many of these relays there actually are on my car.

    Figure 5 on page 7 has one of the main relay blocks located in the engine bay as well as the cold start injector and starter circuit. Looking at this I realised that I have a couple of options. I could wire in the MS to use these stock relays or I could do all my own wiring. The MS instructions state that the injector should be powered by the fuel pump relay. Looking at this diagram it can be seen that there are seperate relays for the EFI, Injectors, Engine, etc. I believe that it will be easier for me to reduce the number of relays and install the system like the MS sites instruct to. I will probably mount a fuse panel with whatever relays i need in the rear trunk of the car. I have a wiring harness from an NA MR2. My plan is to use this to connect the MS to the car for the circuits I need (power to the MS, starter, signal to tach, etc) and remove the rest that I don't need. I will leave the relay block where it is (I still need the starter an cooling fan relays) and mount what I need in the trunk.

    Finally Figure 7 on page nine has the wiring for the stock ECU for the 4A-GZE engine. This schematic gives me an idea of how much simpler the wiring will be with the MS. Firstly the Aiflow meter will be gone This has the stock IAT sensor in it and that will be replaced with a GM unit. The circuit opening relay is what turns the fuel pump off when no air is passing through the airflow meter, this too will be removed. All the Vacuum switching valves (VSV) will be removed. This will cut down on the Vacuum lines quite a bit. All that I will need will be the vacuum line to the brake booster, one to the MS, one to the fuel pressure regulator, and one to my boost gauge.

    Other things I learned from this diagram is that the stock super charger relay is switch on when it receives a ground from the ECU. This works perfectly with the circuit I built for it on the MS. The fuel injectors are run in two banks from the stock ECU. I can only assume that this runs the injectors in a semi-sequential format. This is exactly as the MS is set up. The ignition coil/ignitor/distributor will be removed in favour of a wasted spark directly driven coils.

    Lastly I've been looking at this and toying with the idea of keeping the diagnostic port. From the schematic: FP is the fuel pump. It is connected after the relay so it can be used to either determine if the fuel pump is on or power it through this pin. E1 is a ground. OX is the oxygen sensor reading. I don't know if I can connect this with the wideband inovate sensor I'm planning on using. It has two outputs, one for the MS and one for a gauge. I don't currently know what T is. It is a direct connection to the ECU. The same holds true for VF. I know that in order to set the timing two pins have to be shorted in order to defeat he ECU's control over the electronic advance. I think one of these pins has to be shorted to ground. To be honest I never memorized which pins need to be shorted, I always have a Chilton or Haynes book with me when doing maintenance. +B is twelve volts from the EFI Main relay. Finally IG- is connected to the negative side of the ignition coil. This can be used to drive a tachometer while adjusting timing and idle speed. It shouldn't be too hard to wire this up to work similar to stock. Of course this isn't really necessary as the MS allows you to simply plug in a laptop to see what it is doing. I have a spare from the NA MR2 harness.

    Well that's where I'm sitting now. I am trying to find some DB15 connectors to mount in the MS case for my ignition outputs. I will then mount everything on a piece of wood and use all the sensors and devices that I will use on the engine and make sure that all works before diving into the car's wiring.

    I will update as things happen.

    Cheers,
    Berg

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  24. #24

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    I'm still playing the waiting game on the chips for the JimStim. Sometimes waiting is the hardest part.

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  25. #25

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    Alright, so the chips arrived yesterday.

    I plugged in a new chip and fired up the JimStim to ensure that it was indeed the chip that was causing issues. Everything worked fine.

    I wanted to test the second VR conditioner on the Zeal daughterboard so I set the JimStim to nippon denso mode. The second tach output from the JimStim is simply a squarewave with no zero crossing so it will not trigger the VR circuit without some modification. I have to put a capacitor in series with the signal and add a pull up voltage of twelve volts it should work. Instead of just throwing the parts together and hoping for the best I was planning to use the osciliscope in my office to compare the two tach signals. Unfortunately the scope is being used for another project that is work related so it takes priority (I'm doing most of the work on the MS in my office after hours and during lunch). I probably wont get the scope back until next Wednesday or Thursday.

    I hit another limitation, although this one was expected. I set the JimStim and the MS up for a single toothed wheel and tested everything using Tunerstudio. I then connected the GM ignition coils and tested that at low rpm. I did get a spark but it was weak and inconsistent. My power supply simply did not have the juice to power the coils. Just after firing the coils would charge up again and this sudden demand for current activated the over current protection on the power supply. Although it deactivated before the voltage dropped to zero the coils never got the juice they needed to charge. As such only one coil fired sort of consistently and the other had a very weak spark. The simple solution to this is to use an actual car battery and a battery charger to power everything. Before I even think about doing that I have to go through all my wiring again to make sure it is good and GET FUSES.

    I went to a couple of stores here in town looking for fuse blocks last night. I need to fuse all the systems that are controlled by the MS via relays. The MS has an output that connects to ground when active to drive a relay to turn on the fuel pump. I will be using this output to drive three relays. One will power the fuel pump and O2 sensor. The fuel pump will have a 10A fuse and the O2 a 5A fuse. One wll power both injector banks, each with a 5A fuse. And the last will power the ignition coils. I do not yet know what fuse rating I need. The MS only turns on the fuel pump when the engine is either cranking or running, so controlling the power to the igition and the injectors with this signal will ensure that nothing will get powered or burn up while the engine isnt running.

    Unfortunately the selection of fuse blocks in town is somewhat limited. In fact the only non-glass tube fuse block I could get was a six position block with a common bus down the center. This will work fine for testin purposes, but I was hoping for a little more circuit isolation. To that end I ordered three four position fuse blocks made by Painless from jegs.com. This will allow me to make a slightly neater package. The MS itself requires a 2A fuse.

    At this point I feel that it is probably easiest to bolt everything down to a peice of wood and use that for testing purposes. Once I get that done I'll post up some more pictures. The plan is to then start replacing signals from the JimStim with the actual sensors that wll be on the car and make sure that all runs on the test board. At that point I will be confident that it will work in the car and can finally start the process of removing the old wiring.

    Many people who install these end up wiring a connector to plug into the stock harness so the MS can be plugged right in without rewiring. I have decided not to go that route. I have a spare harness from an NA MR2 that I will use to provide the power from the ignition switch and the signals to the stock gauges. Everything else will be removed. I will make my own harness from the MS to the engine. All the vacuum lines will be removed except the fuel pressure regulator, brake booster, and boost gauge. One more will be added for the MAP sensor. The stock wiring to the oil pressure and coolant temperature sensors will remain, as well as th wiring to the starter and alternator.

    It will be quite a job, but I am looking forward to it. As always, comments and critisms are welcom.

    Cheers,
    Berg

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