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View Full Version : A gen 3 FCD for Lunikins :)



l0ch0w
03-26-2012, 12:44 AM
So... I finished that gen 3 efi proof of concept circuit... here is the o-scope output :)

Its fine tuneable, which is alot more than a simple zener diode can do...

http://img851.imageshack.us/img851/8600/76156035.jpg
By alochow (http://profile.imageshack.us/user/alochow) at 2012-03-25

This means that an adjustable fcd for the gen 3 is quickly becoming a reality...

Luni
03-26-2012, 05:56 PM
Youre my hero Chow Chow!11!

I just repped you. Your meter went from 1 to many pretty fast!

l0ch0w
03-26-2012, 07:01 PM
YAAY!

At any rate, im going to pick up the necessary components and test it out on a bread board... then ill go into production :) hopefully I can cram all that stuff onto the small boards that fit in the normal FCD housing. Otherwise, i have another idea, but itll mean a secondary enclosure...

joe's gt
03-27-2012, 04:17 AM
Lets see the circuit!

l0ch0w
03-27-2012, 05:23 AM
uh... no...

Ill make one, and prove it works...

If i make the plans available to everyone, i wont be able to make money :P

joe's gt
03-28-2012, 03:45 AM
Is this for a business or something? Is this going to be patented?

l0ch0w
03-28-2012, 07:17 AM
Cant say that its really worth patenting, since industry wont be super interested in it.
I can say that i did put quite a bit of work figuring this stuff out, and for all of it to go to waste because the plans are made simple to everyone to copy, then im out money for the time I spent working on it. Remember... time=money...

alltracman78
04-05-2012, 02:40 AM
Why would a gen III FCD be any different than a gen II FCD?
They use the exact same signal...

l0ch0w
04-06-2012, 05:55 AM
Why would a gen III FCD be any different than a gen II FCD?
They use the exact same signal...

Because the gen 3 EFI uses the signal from the MAP sensor as a load sensor wheras in a gen 2 motor the sensor is ONLY used for the fuel cut and controlling the lame-o stock boost gauge... It sort of replaces the large flappy-door VAFM. The gen 3 is designed to be used as a load sensor, it operates in a very different way from the gen 2 VAFM load sensor.

Basically if you just added a resistor/potentiometer to a gen 3 map sensor, it would affect the entire tune causing it to run too lean throughout its load cycle. In order to combat this, the input and output must be the same right up until the fuel cut line is hit. Because fuel cut is set at a straight 4.4v reading from the sensor, as long as the ECU never actually sees 4.4v, the ecu is tricked into thinking that the motor is at a safe enough boost level to not activate fuel cut...

I wouldnt have gone to these lengths to design a circuit that performs this way if the solution was as simple as making a simple potentiometer based FCD... which I already make btw for the gen 2 if you havent already seen... (my little plug *cough* *cough*)

l0ch0w
04-06-2012, 05:58 AM
At any rate, im in the process of building the test rig, once it is running I will post video of it operating correctly.

http://img710.imageshack.us/img710/1418/cgosms20120329100329.jpg
By alochow (http://profile.imageshack.us/user/alochow) at 2012-04-05

Luni
04-06-2012, 07:35 PM
You so smart Chow Chow!

4thgenceli
04-06-2012, 07:48 PM
Boost noob coming out.

Fuel cut = car overboosts (failed wastegate, something). ECU detects this, it kills power to injectors

This thing you made simply raises the stock fuel cut (ie from 8lb to 12lb boost).

What benefit would this do me on my st215 swap when my stock boost limit is around 20psi?

Luni
04-06-2012, 07:55 PM
It would allow you to run a bigger turbo than your shitty stock one, and boost over 20 psi :p

l0ch0w
04-06-2012, 08:38 PM
^you'd want to be careful though... the 540cc stock gen 3 injectors will start to run out of juice at about 21-24psi depending on your ve capabilities. Its VERY VERY important to have a wideband with this so you can be sure that you arent running too lean... I should include a disclaimer huh...

4thgenceli
04-06-2012, 09:02 PM
I don't quite want to run 25psi yet... lol.

Luni
04-06-2012, 11:45 PM
^you'd want to be careful though... the 540cc stock gen 3 injectors will start to run out of juice at about 21-24psi depending on your ve capabilities. Its VERY VERY important to have a wideband with this so you can be sure that you arent running too lean... I should include a disclaimer huh...

Sure, if you feel its your job to babysit idiots. I guess to cover your ass legally.

I mean, you can put an ATS modified FPR on a Gen3 rig, and you can run up to 350-370whp with the Gen3 ECU. You can run a piggyback with it if youd like, theres all sorts of things you can do.

l0ch0w
04-07-2012, 03:39 AM
Sure, if you feel its your job to babysit idiots. I guess to cover your ass legally.

I mean, you can put an ATS modified FPR on a Gen3 rig, and you can run up to 350-370whp with the Gen3 ECU. You can run a piggyback with it if youd like, theres all sorts of things you can do.

I thought when you modify the stock fuel pressure you have to get a piggyback? Otherwise the injector time table will not match the load points?

joe's gt
04-07-2012, 06:53 AM
Idk, I think it would be pretty easy to build a diy FCD for any MAP based car or even the Gen 2 for that matter. All you need is a simple voltage follower circuit in between the sensor and ecu that allows the sensor voltage to pass through up until a max voltage point that corresponds to a max boost pressure.

This could easily be accomplished using 2 or 3 Op-Amps. One as a voltage follower and 2 others as a comparaters that feed the signal to the ecu and cuts the signal to the injectors when the sensor voltage goes above a max reference voltage corresponding to a max boost pressure. The reference voltage would be adjustable by a potentiometer and would represent the adjustable boost pressure you want fuel cut set at. The comparater op amp outputs either the sensor voltage or reference voltage (whichever is larger) and feeds it to the ecu and a separate op amp would act as a second comparater and turn off the injectors by using an output voltage to switch a relay that is installed before the injectors and effectively opening the injector circuit. You could also use the second op amp as a voltage clamp and just use it to set the max voltage the ecu sees so once you boost above your max boost pressure, the ecu is only providing enough fuel for your max boost pressure. I would think cutting off the injectors would be better, because a voltage clamp might result in a lean condition and detonation.

My electronics knowledge isn't the best, so maybe someone else can chime in. Where's Nuke when you need him?

Anyways, here is an example of an interesting voltage clamp FCD circuit. Its a pretty good circuit, incorporating high input impedance (which helps the circuit components not act as loads and transmit voltages better) and filtering stray frequencies using a capacitor.

http://makecircuits.com/fcd-fuel-cut-defencer.html

l0ch0w
04-07-2012, 04:04 PM
You dont need 2 op amps to do this :)

Im using the stock 5v reference supplied by the ecu to power the op amp and it doesnt change. The circuit is adjustable using a pot that feeds the V(in) on the op amp.

While in theory the circuit might be easy to design, because of tolerance levels and variance, you have to tune each individual module to the desired operation level, which is impossible to do on the vehicle, and a test rig is necessary.

joe's gt
04-07-2012, 11:12 PM
What op amp are you using? Does this have rail to rail capacity? If your input voltage comes close to your supply voltage the output voltage will be distorted and incorrect if you are using an op amp not designed for rail to rail capacity. This is why a 2 op amp circuit would be much more stable. You take the 12v supply from the battery to power the op amps and that way your supply voltage is always much higher than the 5v reference voltage and you don't ever have to worry about an incorrect output signal because the reference won't ever be near the supply.

Again, my electronics knowledge is limited, but I do know that designing rail to rail is like playing with fire. It is pretty easy to just use the battery's 12v supply and there are numerous chips that incorporate two op amps into one that cost cents.

l0ch0w
04-08-2012, 04:57 PM
^ Im not using mine the way you think I am :)
The circuit I am using only using the op amp as a comparator. In fact the input voltage on my op amp is technically negligible, its rail voltage is unimportant for my circuit design.

Plus if I started pulling 12V i couldnt make the unit Plug n play. The 5V ref design is purely for ease of Plug n play capabilities.

The ideal principal behind and op amp is that they essentially amplify the input voltage by an infinite amount. In reality its on the magnitude of 100k or something like that.

Rail to rail is the concept that the power rail voltages and input voltages are very close to eachother, which is not the case within my circuit.

Just relax man :) if the test circuit works well, then the concept will be proven. If it doesnt work, then you can laugh at me ok :D

alltracman78
04-08-2012, 08:20 PM
Because the gen 3 EFI uses the signal from the MAP sensor as a load sensor wheras in a gen 2 motor the sensor is ONLY used for the fuel cut and controlling the lame-o stock boost gauge... It sort of replaces the large flappy-door VAFM. The gen 3 is designed to be used as a load sensor, it operates in a very different way from the gen 2 VAFM load sensor.
Yes, I understand all this. :) I wouldn't be a Master Tech if I didn't. It works the same way as the 5SFE [roughly speaking].


Basically if you just added a resistor/potentiometer to a gen 3 map sensor, it would affect the entire tune causing it to run too lean throughout its load cycle. In order to combat this, the input and output must be the same right up until the fuel cut line is hit. Because fuel cut is set at a straight 4.4v reading from the sensor, as long as the ECU never actually sees 4.4v, the ecu is tricked into thinking that the motor is at a safe enough boost level to not activate fuel cut... All you NEED is a zener diode, same as a gen II.
If you're just adjusting the signal at the top why do you need a [relatively?] complicated circuit to do what a zener diode can do? I'm asking because I'm curious, not to be a dick. :)
What does this do to the signal?
Is this supposed to work in conjunction with something else?

joe's gt
04-09-2012, 06:47 AM
^ Im not using mine the way you think I am :)
The circuit I am using only using the op amp as a comparator. In fact the input voltage on my op amp is technically negligible, its rail voltage is unimportant for my circuit design.

Plus if I started pulling 12V i couldnt make the unit Plug n play. The 5V ref design is purely for ease of Plug n play capabilities.

Rail to rail is the concept that the power rail voltages and input voltages are very close to eachother, which is not the case within my circuit.

Just relax man :) if the test circuit works well, then the concept will be proven. If it doesnt work, then you can laugh at me ok :D

This is contradictory though, because if you are using the op amp as a comparater, you would have to be comparing the input signal from the sensor to some reference that is hopefully adjustable by a potentiometer (represents your max boost pressure). That means if you are using a single op amp as up to a 5v comparater in a voltage follower configuration that is also powered by 5v, if your input voltage swings close to that 5v power supply, the output signal COULD (not saying that it will) get distorted if your not using an op amp specifically designed for rail to rail capacity. Your right, input voltage is not close to rail voltage UNTIL the input voltage swings close to 5v and then it becomes very relevant, so much so that it could distort the output signal and give a false reading to the ecu (very bad for high boost applications). So when input and rail voltages can be the same in a comparater/voltage follower configuration, it is NOT negligible. Heck I don't even have access to these sensors, so the input voltage that comes close to 5v might correspond to an unreasonably high boost pressure, so your 5v comparator circuit might be safe using a 5v power supply.

The only reason I'd like to see actual emperical test data is because you are already selling these things, so it would be nice to know what boost pressures the sensor voltages correspond to and see that the op amp correctly acts as a voltage follower through the range that it is suppose to and then either clamps the voltage or triggers whatever its suppose to do at the adjustable voltage specified by the potentiometer. It worries me that you say "If the test circuit works well, then the concept will be proven", yet you have already sold a bunch of these. And I won't laugh at you, the reason I wanted you to post the circuit in the first place is because there are so many knowledgeable minds on this forum that could all pitch in to help hopefully create the perfect diy fcd. The sharing of information is for the benefit of the community. I'm sure you could still make quite a profit from people who don't want to go through the trouble of making their own. There's extra little things that can be added to the circuit that sometimes people forget like increasing input impedance and filtering.

joe's gt
04-09-2012, 07:13 AM
All you NEED is a zener diode, same as a gen II.
If you're just adjusting the signal at the top why do you need a [relatively?] complicated circuit to do what a zener diode can do? I'm asking because I'm curious, not to be a dick. :)
What does this do to the signal?
Is this supposed to work in conjunction with something else?

From what I understand, a zener diode completely eliminates fuel cut and l0ch0w's solution is an adjustable FCD. People are scooping them up without any posted test results yet. With this configuration, if the op amp circuit is not working correctly it could be messing up the signal throughout the entire boost range where as a zener diode won't touch the signal, it will just eliminate fuel cut. I'd wait for the test results before purchasing. Most likely it is fine though. I believe it is just a simple op amp voltage follower circuit with a voltage clamp that is adjusted using a potentiometer. Since he is using a 5v power supply and a input signal that could possibly reach 5v there is the possibility of output distortion if the input gets close to 5v if not using the correct op amp. Most likely the boost never gets high enough to force the sensor signal close enough 5v to matter tho, so for the most part I bet the circuit works as it should. The adjustable reference voltage (max boost pressure) for fuel cut is well below 5v anyway so everything probably works correctly.

alltracman78
04-09-2012, 06:12 PM
So allows the boost signal to raise normally and until it gets to just below 4.4V and basically "clamps" the signal there until you reach the boost level you want, and then it allows the signal to raise to 4.4v and trigger boost cut?

l0ch0w
04-09-2012, 06:38 PM
^if you wanted to retain fuel cut capabilities, you would need a secondary map sensor as the stock one runs out of puff at like 21psi or something like that... i havent gotten a chance to test that...

l0ch0w
04-09-2012, 06:41 PM
Yes, I understand all this. :) I wouldn't be a Master Tech if I didn't. It works the same way as the 5SFE [roughly speaking].

All you NEED is a zener diode, same as a gen II.
If you're just adjusting the signal at the top why do you need a [relatively?] complicated circuit to do what a zener diode can do? I'm asking because I'm curious, not to be a dick. :)
What does this do to the signal?
Is this supposed to work in conjunction with something else?

Because a zener diode has both limited, and a wide tolerance for what its breakpoint voltage is. You could run a 4.3v zener, but with a 5% tolerance, it might be possible for it to not work at all, or even start clamping way too early... The more complicated circuit allows you to adjust the voltage at which clamping occurs...

The problem with running a zener diode on a gen 2 circuit is that you cant fine tune where you want fuel cut to happen...

When I finalize my gen 3 design, Im considering making a second box that allows you to retain some sort of fuel cut. Because the gen 3 map sensor runs out of juice at some point, you would need a secondary map sensor to trigger fuel cut voltage.

l0ch0w
04-09-2012, 06:43 PM
This is contradictory though, because if you are using the op amp as a comparater, you would have to be comparing the input signal from the sensor to some reference that is hopefully adjustable by a potentiometer (represents your max boost pressure). That means if you are using a single op amp as up to a 5v comparater in a voltage follower configuration that is also powered by 5v, if your input voltage swings close to that 5v power supply, the output signal COULD (not saying that it will) get distorted if your not using an op amp specifically designed for rail to rail capacity. Your right, input voltage is not close to rail voltage UNTIL the input voltage swings close to 5v and then it becomes very relevant, so much so that it could distort the output signal and give a false reading to the ecu (very bad for high boost applications). So when input and rail voltages can be the same in a comparater/voltage follower configuration, it is NOT negligible. Heck I don't even have access to these sensors, so the input voltage that comes close to 5v might correspond to an unreasonably high boost pressure, so your 5v comparator circuit might be safe using a 5v power supply.

The only reason I'd like to see actual emperical test data is because you are already selling these things, so it would be nice to know what boost pressures the sensor voltages correspond to and see that the op amp correctly acts as a voltage follower through the range that it is suppose to and then either clamps the voltage or triggers whatever its suppose to do at the adjustable voltage specified by the potentiometer. It worries me that you say "If the test circuit works well, then the concept will be proven", yet you have already sold a bunch of these. And I won't laugh at you, the reason I wanted you to post the circuit in the first place is because there are so many knowledgeable minds on this forum that could all pitch in to help hopefully create the perfect diy fcd. The sharing of information is for the benefit of the community. I'm sure you could still make quite a profit from people who don't want to go through the trouble of making their own. There's extra little things that can be added to the circuit that sometimes people forget like increasing input impedance and filtering.



Dude... i havent even physically made the circuit for a gen 3 fcd. This thread is just a proof of concept...

the gen 2 ones im making and selling are just old school potentiometer based ones packaged neatly...

dont be a dick...


Also, The op amp is NOT drawing directly from the sensor input voltage... the design of my circuit can essentially use any rail voltage to supply the op-amp... The op amp in my circuit sees a max of 12uV across the inputs... Lay off me already...

Like I said before, just wait for me to put together my test rig, and ill prove it works... till then its all just a concept.

l0ch0w
04-12-2012, 08:11 AM
Test rig is complete, now i have to make a bunch of jumpers for my breadboard, and we can set this thing straight :)

l0ch0w
07-31-2012, 04:50 AM
Behold...

http://imageshack.us/a/img708/5323/imag0428p.jpg
By alochow (http://profile.imageshack.us/user/alochow) at 2012-07-30

http://imageshack.us/a/img407/5242/imag0430v.jpg
By alochow (http://profile.imageshack.us/user/alochow) at 2012-07-30

http://imageshack.us/a/img833/7800/imag0431w.jpg
By alochow (http://profile.imageshack.us/user/alochow) at 2012-07-30

Im ready to go test it :)

Borinal
08-04-2012, 05:13 AM
Awesome dude, very nice. They look great. I'm assuming that it worked?

Luni, isn't this the kind of stuff that Emily does?

l0ch0w
08-04-2012, 07:02 PM
My stupid test rig is giving me fits.

Im probably going to need to hook this up to my standalone to test it properly.

CollapsedNut
08-05-2012, 03:33 AM
You ain't done yet?

l0ch0w
08-05-2012, 02:43 PM
^says the boy with no turbo...

l0ch0w
08-09-2012, 03:24 AM
It works... hooked it up to my standalone and it works perfectly... even has adjustable fuel cut capabilities...

l0ch0w
08-09-2012, 08:32 AM
http://imageshack.us/a/img690/1909/imag0441fv.jpg
By alochow (http://profile.imageshack.us/user/alochow) at 2012-08-09

Well...

It aint as pretty or elegant as the previous versions IMO...

But they still look pretty stealthy I think...

Either way, here is the first ever plug and play FCD for the toyota.

I say toyota because this will work on any boosted MAP based toyota... not just gen 3 swaps or gen 4 swaps, but also Supras...

Look at the mess you made me make :|

http://imageshack.us/a/img31/7719/imag0442d.jpg
By alochow (http://profile.imageshack.us/user/alochow) at 2012-08-09

l0ch0w
08-10-2012, 05:52 AM
Here be the proof!:

http://youtu.be/Hb4FQ4PTsOM

Excuse the background noise...

joe's gt
08-11-2012, 07:11 AM
Purty sweet. Cool to see the voltage clamp in action. Glad to see you used a rail to rail op amp as well assuming that your supply voltage is 5v, because it looks like at 16 psi the voltage is up around 4.9 volts, unless I misinterpreted the video.

l0ch0w
08-11-2012, 03:12 PM
The only reason the voltage is showing 4.9V at that point is because the fuel cut adjustment knob has been turned up to initiate fuel cut at 16psi.

Note, I was using a gen 2 Turbo Pressure sensor as my reference during the video test. There is really no difference between the sensors in operation other than the scaling on the pressure and voltage.

If you turn it all the way down, there is no fuel cut. The FCD will hold its voltage at 4.3V all the way up to the sensor's max output. If you watch the vid from 1:35 to 2:10 you will see how it operates when the fuel cut adjustment is set to eliminate fuel cut altogether.

This graph better illustrates how it works when using a gen 3 MAP sensor:

http://imageshack.us/a/img38/4569/fcdoperation1.png
By alochow (http://profile.imageshack.us/user/alochow) at 2012-08-09

l0ch0w
08-11-2012, 08:06 PM
GB has been posted here: http://www.celicatech.com/forums/showthread.php?56412-LP-Engineering-PnP-Fuel-Cut-Defender-GB

joe's gt
08-12-2012, 04:58 PM
Good to know. So even if someone wants fuel cut in ranges above 20 psi, the voltage will still be well below five volts. A lot of times you don't even get this kind of info from manufacturers. Consumers just throw it on and hope and pray its designed right. Nice to see some empirical evidence of operation behind the design. Nice work l0ch0w!!!

l0ch0w
08-17-2012, 03:32 PM
I found my gen 3 map sensor last night and tested out the actual voltage at 17psi, turns out its right at 4v.

The new clamp voltage is just under 4 volts now (like 3.98 volts)

karl
08-24-2012, 05:44 AM
Good to know. So even if someone wants fuel cut in ranges above 20 psi, the voltage will still be well below five volts. A lot of times you don't even get this kind of info from manufacturers. Consumers just throw it on and hope and pray its designed right. Nice to see some empirical evidence of operation behind the design. Nice work l0ch0w!!!

I'm actually surprised no one has built these before. The circuit is surprisingly simple :D

Hookecho
08-24-2012, 04:29 PM
Doesn't sound that simple to me.

l0ch0w
08-24-2012, 06:33 PM
I'm actually surprised no one has built these before. The circuit is surprisingly simple :D

It took me awhile to figure it out... I actually had quite a bit of help from a really smart guy from over on the MR2 forums...

Its operation is simple, but getting a suitable rail-to-rail operational amplifier circuit do do what you want it to is tricky. Remember... these are plug and play and dont require a 12v supply...

Luni
08-24-2012, 08:54 PM
Wheres my damn FCD at chow chow?

karl
08-24-2012, 10:47 PM
It took me awhile to figure it out... I actually had quite a bit of help from a really smart guy from over on the MR2 forums...

Its operation is simple, but getting a suitable rail-to-rail operational amplifier circuit do do what you want it to is tricky. Remember... these are plug and play and dont require a 12v supply...

I know. I sent you the schematic for it :D

karl
08-24-2012, 11:06 PM
Doesn't sound that simple to me.

It really is though. It took me about 20 minutes to throw the schematic for it together. I got the idea for adjustable fuel cut when someone said it was impossible to do with the stock sensor. What can I say, I guess I have an electron fetish. I actually started class on Tuesday to get my BSEE.

l0ch0w
08-25-2012, 05:18 AM
^ oh... karl... I didnt make the connection :)

Karl is a smart dude :bowdown: , I had the PnP idea first on the gen 2 units, and while I had a circuit that involved a 12v input that would have worked, it would not have been plug n play, Karl worked the magic to get the RTROA working, and to him i am very grateful.

l0ch0w
08-25-2012, 05:26 AM
Wheres my damn FCD at chow chow?


Its in a box that I have to take it out of so I can readjust it... Unless u are cool with trying to dial it in on your own :)