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djorkaef
12-24-2008, 04:53 PM
Hi,

I'm the proud owner of a 5th gen 3s-ge Celica (Belgium), and I want to make some steps to get my 0-100 kph faster than 8.4 seconds. K&N air filter (conic) is ordered.

Next, when I do some e-bay searches on 'Celica' I always find those 'celica performace upgrade boxes' very cheap (starts at 30 usd) which 'guaranty' up to +10 hp. I think they are most of all controllers that use OČ outlet + inlate temperature sensor, these boxes then manipulate the temperature sensor output, so the injectors add more fuel. When I do other searches on the internet I also find 'chip tuning for Celica' at a garage, for prices of 400 usd and more. Don't know the differences.

http://cgi.ebay.com/ebaymotors/BEST-PERFORMANCE-CHIP-TOYOTA-CELICA-90-05-FUEL-SAVER_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1205Q7c66Q3 a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a0Q7c293 Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZit em220331712962QQitemZ220331712962QQptZMotorsQ5fCar Q5fTruckQ5fPartsQ5fAccessories

http://cgi.ebay.com/ebaymotors/Toyota-Celica-Corolla-MR2-NL-Performance-Chip-Module_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1205Q7c66Q 3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a0Q7c29 3Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZi tem200283582047QQitemZ200283582047QQptZMotorsQ5fCa rQ5fTruckQ5fPartsQ5fAccessories

http://cgi.ebay.com/ebaymotors/25HP-D-BOOST-PERFORMANCE-CHIP-TOYOTA-MR2-TERCEL-CELICA_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1205Q7c66Q 3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a0Q7c29 3Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZi tem110328142707QQitemZ110328142707QQptZRaceQ5fCarQ 5fParts

list goes on and on...

@ tuning store http://www.bullpower.nl/chiptuning/benzine/toyota.html

Anybody who knows more about these things? I think for optimal performance these 'powerboxes' can't be just plug and play? Some of them have fine-tune buttons and others don't. I really want to optimise my injection setup with a reliable system for a good price.

Because there's so much for sale I have no idea what will work and what is fake. I really need some recommandations you know, I'm sure I'm not the only person who ever thought about optimising ECU.

Please some help. Wish you Merry Christmas and Happy New Year!

Grot
12-24-2008, 05:20 PM
Honestly the "powerboxes" seem fake as hell.

The chip is probably the same, but would need a link to be sure.

djorkaef
12-24-2008, 06:06 PM
I added some links to ebay articles but what i'm searching for is a good one that somebody here has in use.

ciento44
12-24-2008, 06:07 PM
I don't think anyone here uses them... because they're proven to add no power in a car that runs rich to start with, and just hurts your gas mileage.

CptActnMan
12-24-2008, 06:08 PM
its like a super cheap Super-AFC, i wouldn't trust it, not with a name like "Jaw Dropper Performance" sounds like they are compensating.

if you really want a A/F computer get this ->
click here (http://motors.shop.ebay.com/_Car-Truck-Parts-Accessories__super-afc_W0QQ_fxdZ1QQ_ptasZ1QQ_trksidZm39)

djorkaef
12-24-2008, 06:14 PM
I don't think anyone here uses them... because they're proven to add no power in a car that runs rich to start with, and just hurts your gas mileage.
how do you mean a car that runs rich to start with?

if i read all this 'crap' on the ebay articles, some things do make sense.

like the factory 'injection setup' is chosen so that the car performs in the worst conditions, from dusty desert to freezing canada, from high mountains to sea level. that's why, they say, the standard setup in 'normal driving circumstances' is way beneath the tollerances the motor can handle. so it seams logical to me that injecting more fuel will be efficient in some circumstances, and that this can be arranged by manipulating themperature input makes also sense isn't it?

i've also seen 7 sec youtube videos were said 'injection setup changed for more hp/torque'. that can't all be fake? or is it?

ciento44
12-24-2008, 06:16 PM
how do you mean a car that runs rich to start with?

if i read all this 'crap' on the ebay articles, some things do make sense.

like the factory 'injection setup' is chosen so that the car performs in the worst conditions, from dusty desert to freezing canada, from high mountains to sea level. that's why, they say, the standard setup in 'normal driving circumstances' is way beneath the tollerances the motor can handle. so it seams logical to me that injection more fuel will be efficient in some circumstances, and that this can be arranged by manipulation themperature input makes sence to me.

i've also seen 7 sec youtube videos were said 'injection setup changed for more hp/torque'. that can't all be fake? or is it?

Sure....

If your motor makes enough power or has demand that it NEEDS more fuel. Which, you don't.

And s-series motors as a rule run rich to start. You can actually gain power by LEANING them out.

djorkaef
12-24-2008, 06:43 PM
this is that youtube vid

http://www.youtube.com/watch?v=XzjQjrlH0lw

i will ask him what he meant with 'injection setup'.

i will also search some more documentation about the AFC.

RedRkt01
12-24-2008, 07:42 PM
I'm lurking........

djorkaef
12-24-2008, 07:57 PM
i just searched some info on the net about one specific mod, called the 'tri-phase'

http://www.nextlevelracing.com/triphase.html

this forum is full of good reactions, say putting the thing ON is a remarkeble gain in power:

https://www.team-bhp.com/forum/accessory-parts-reviews/17130-tri-phase-reports.html

on this forum, most people say its nothing more than a useless resistor that makes your car drive riche all the time, but they never bought it:

http://www.fitfreak.net/forums/fit-jdm-tuning-engine-modifications-swaps/34424-next-level-performance-tri-phase-module.html

ciento44
12-24-2008, 07:58 PM
Well then give it a shot.

djorkaef
12-24-2008, 08:10 PM
These things are on the market for years, if nobody of this celica-fan forum has installed it, I seriously doubt it has any gain, because if it had, everybody would install this, like cold air intakes and sport exhausts (with even less gain than +20 hp :P). But clearly it hasen't done that. So thank you.

Kastigir
12-24-2008, 08:10 PM
It's all BS. Proper tuning will gain you more power than some *magic* box.

nuclearhappines
12-24-2008, 08:14 PM
What these do is they typically connect to your intake air temp sensor to make the ECU think that there is cooler air coming in and advance the timing a little bit.

Here's a combo that will out do this 'chip' (and give you at least double the gains).

You need a 4k ohm 1/4 watt resistor
A ~4.3 to 4.7 volt zener diode with a rating of some 100mA
Two 1k ohms potentiometers ... capable of flowing some 20 to 30mA each.

you can get all three at radio shack:

1- Timing advance: Cut one of the two wires going to your air intake temp sensor, solder your 4k ohm resistor in series. This will make the ecu think it's 30* colder out and may advance your timing by 2-3*. use of high octane gas may be required.

2- Typical 5sfe will run as rich as 11.5:1 at the top end. To bring this down to a more reasonable 13.0:1 would mean that you need to lean out the fuel curve by 15% at peak.
With an ohm meter adjust one of your 10k pots to where there are 850 ohms between terminals 1 and 2, and 150 ohms between terminals 2 and 3.

Now cut the wire going from the MAP sensor signal to the PIM pin on the ECU.
Wire the sensor side of this wire to terminal 3, wire terminal 1 to ground, wire terminal 2 to the PIM (ECU side) of the cut wire.

3- Throttle Enhancer:
With an ohm meter adjust one of your 10k pots to where there are 500 ohms between terminals 1 and 2, and 500 ohms between terminals 2 and 3.

Cut the main 5 volt power source going to your throttle position sensor.
Wire up a 12v-14v source to terminal 3 on your pot,
Wire up terminal 1 to ground.
Wire up terminal 2 a supply the TPS with a voltage that will vary between 6 and 7 volts depending on your 'charging' voltage when the car is running.

Take your diode + side and Tee into the wire going to the ECU for TPS signal.
Take your diode - side and wire it to ground.


With this combo. Your ecu will see 20% more throttle angle which will make the car a bit more responsive in switching between open and closed loop, on auto cars it may decide to downshift sooner too. It will also slightly advance timing improving torque, and it will lean out your top end (not by much at idle, but significantly when you are 0psi (WOT) )...

The combo is worth some 8-10 hp at peak if done correctly.

All the stuff you buy on ebay is one of the three mentioned above. These are also sold in different forms as different things.... HKS AFR Type L (fuel), Sprint booster (throttle), and the famous ebay chip (timing).

If you really know what you're doing you can fit all of those parts in a small black box and wire it near the ECU so it will be invisible.

djorkaef
12-24-2008, 09:47 PM
What these do is they typically connect to your intake air temp sensor to make the ECU think that there is cooler air coming in and advance the timing a little bit.

Here's a combo that will out do this 'chip' (and give you at least double the gains).

You need a 4k ohm 1/4 watt resistor
A ~4.3 to 4.7 volt zener diode with a rating of some 100mA
Two 1k ohms potentiometers ... capable of flowing some 20 to 30mA each.

you can get all three at radio shack:

1- Timing advance: Cut one of the two wires going to your air intake temp sensor, solder your 4k ohm resistor in series. This will make the ecu think it's 30* colder out and may advance your timing by 2-3*. use of high octane gas may be required.

2- Typical 5sfe will run as rich as 11.5:1 at the top end. To bring this down to a more reasonable 13.0:1 would mean that you need to lean out the fuel curve by 15% at peak.
With an ohm meter adjust one of your 10k pots to where there are 850 ohms between terminals 1 and 2, and 150 ohms between terminals 2 and 3.

Now cut the wire going from the MAP sensor signal to the PIM pin on the ECU.
Wire the sensor side of this wire to terminal 3, wire terminal 1 to ground, wire terminal 2 to the PIM (ECU side) of the cut wire.

3- Throttle Enhancer:
With an ohm meter adjust one of your 10k pots to where there are 500 ohms between terminals 1 and 2, and 500 ohms between terminals 2 and 3.

Cut the main 5 volt power source going to your throttle position sensor.
Wire up a 12v-14v source to terminal 3 on your pot,
Wire up terminal 1 to ground.
Wire up terminal 2 a supply the TPS with a voltage that will vary between 6 and 7 volts depending on your 'charging' voltage when the car is running.

Take your diode + side and Tee into the wire going to the ECU for TPS signal.
Take your diode - side and wire it to ground.


With this combo. Your ecu will see 20% more throttle angle which will make the car a bit more responsive in switching between open and closed loop, on auto cars it may decide to downshift sooner too. It will also slightly advance timing improving torque, and it will lean out your top end (not by much at idle, but significantly when you are 0psi (WOT) )...

The combo is worth some 8-10 hp at peak if done correctly.

All the stuff you buy on ebay is one of the three mentioned above. These are also sold in different forms as different things.... HKS AFR Type L (fuel), Sprint booster (throttle), and the famous ebay chip (timing).

If you really know what you're doing you can fit all of those parts in a small black box and wire it near the ECU so it will be invisible.
that's great! i surely will try to get this all in one solid boxe and make a video before and after. one thing: its not a 5sfe but a 3sge motor. so any differences?

RedRkt01
12-25-2008, 01:34 AM
that's great! i surely will try to get this all in one solid boxe and make a video before and after. one thing: its not a 5sfe but a 3sge motor. so any differences?

I don't think so. Both motors share lots of equipment even across markets.

nuclearhappines
12-25-2008, 09:02 AM
3SGE is different because of the AFM

djorkaef
12-25-2008, 12:35 PM
Is the 3GSE AFM then high enough not to be adjusted at 7000 rpm?

nuclearhappines
12-25-2008, 02:26 PM
what happened to the AFM page in the BGB ?

RedRkt01
12-25-2008, 09:18 PM
3SGE is different because of the AFM

I don't believe the 2nd Gen 3SGE had an AFM. I couldn't find it anywhere in the EPC.

djorkaef
12-26-2008, 01:22 PM
In nuclearhapines-writing the AFM-sensor never comes to mention,

only
-temp IN-sensor
-MAP-sensor (manifold absolute pressure)
-trottle-sensor

which I all have.

so why would that be a problem? and what is ment by AFM? Air Fuel Mix? Or Air Flow Meter.

gerby77
12-28-2008, 12:38 AM
hi,

lots of greetings from the Netherlands in front.
I'm getting an Apexi S-AFC soon, i think that it will be wiser to use
such a device
But what you will need further is a wideband o2 sensor (for example the Innovative LC-1 -> which i'm getting soon too)

I'm getting this because i want to see how much i can reach with it. Won't be soo much, but if you want reach more power better get a 3s-gte ;-)

djorkaef
12-28-2008, 03:54 PM
I know but i like my 3s-ge too much, when cleaned with simple water it still looks like new. Can't lose this motor : )

http://img91.imageshack.us/img91/8263/p1170908om6.jpg

That's a 19 year old, stock engine @ 199.000 km

Isn't she a beauty : P Try finding a 3s-gte that looks like that.

gerby77
12-28-2008, 06:24 PM
I know but i like my 3s-ge too much, when cleaned with simple water it still looks like new. Can't lose this motor : )

http://img91.imageshack.us/img91/8263/p1170908om6.jpg

That's a 19 year old, stock engine @ 199.000 km

Isn't she a beauty : P Try finding a 3s-gte that looks like that.

Wow, that's really nice! keep it like that ;-)
come and show it to me once. hehehe

djorkaef
12-31-2008, 10:26 AM
Is it save to install this SAFC without the use of a dyno? Cause on the base of what are you going to increase the amount of fuel, I think you can't just put it all on maximum. Or is that where you're buying the advanced o2 sensor for?

gerby77
12-31-2008, 11:31 AM
Is it save to install this SAFC without the use of a dyno? Cause on the base of what are you going to increase the amount of fuel, I think you can't just put it all on maximum. Or is that where you're buying the advanced o2 sensor for?

a friend of mine has the apexi with a wideband o2 sensor in his Corolla with a 3s-ge motor in it, and i will go onto a dyno.
But i can check if the values are ok with the o2 sensor, so shouldn't be much of a problem.

djorkaef
01-03-2009, 12:31 AM
Can someone please explain some questions?

Because as far as i get it, rich mixure = save, lean = dangerous (why?), and if you want to make the car faster and more HP, you add more fuel so more rich. So doesn't that mean you're always save??

2d question: what do you need a dyno for? is an O2 meter not good enough to see the mixure is good?

3d question: how do most cars fuel mixure changed on rpm. is 2000 rpm more riche than 6000 rpm?

MrTurrari
01-03-2009, 03:17 AM
Is it save to install this SAFC without the use of a dyno? Cause on the base of what are you going to increase the amount of fuel, I think you can't just put it all on maximum. Or is that where you're buying the advanced o2 sensor for?
Yes, if you are only making minor changes and use a wideband O2 sensor to see where your mixture is at any given RPM. Understand that you will only be able to change things at WOT which is 75-80% throttle position and above . All areas under that will be mixed by the ECU using the stock narrowband O2 sensor and you have no control over that. If you are using larger injectors then you have to pull more fuel and it will advance timing. If you have a knock sensor you are usually ok but if not then you need to be more careful about pulling fuel. Forced induction also raises the risks because there are more transitional states the motor can be in at different RPMs.


Because as far as i get it, rich mixure = save, lean = dangerous (why?), and if you want to make the car faster and more HP, you add more fuel so more rich. So doesn't that mean you're always save??
Rich usually equals safe but only up to a point. A/F ratios somewhere below 9:1 begin to risk washing down the cylinder which removes the oil keeping the rings from digging into the cylinder walls. You start too loose power when you go too rich too. We are talking about fuel injected cars here so the ratios are already a very good compromise between power and safety. It depends on engine design but generally speaking going richer will not add much power on these engines. You must add more air first and then match it with a proportionate amount of fuel. That takes physically modifying the engine in some way (cams, header, porting, exhaust, turbo) to get more air in. Going leaner will usually add power but there is a point where bad things will start to happen. Lean is dangerous because it creates more heat then the engine can shed into the cooling system. Once the heat builds up you can have pre-ignition or detonation also called knocking. At some point it get so hot that aluminum parts start to melt or the force from the uncontrolled burning is so great that it crushes bearings or ring lands.


2d question: what do you need a dyno for? is an O2 meter not good enough to see the mixure is good?

A wideband O2 is good enough if you can log it or have a friend drive and you watch the ratios at the different RPMs. The advantage of a dyno is that they can log everything and also listen for detonation right there in the engine bay. You can do that too but you need some special equipment to do it while you are driving.


3d question: how do most cars fuel mixure changed on rpm. is 2000 rpm more riche than 6000 rpm?
Fuel injected cars are usually leaner at lower RPMs where knocking is less likely to cause damage. They then level off in the mids and get slightly richer towards the top.

djorkaef
01-03-2009, 02:38 PM
Thanks a lot for that reaction MrTurrari! Very interesting!

So here the respond. You say, making the mixure leaner will also gain power.

I checked some engineering books and see the point of maximum power is around lambda = 0,8 (11.8:1). The book says the ECU tries to hold lambda = 1 (14.7:1) for most efficient fuel economy regarding minimum NOx, and that's realised by the feedback of the smallband o2 sensor (so independent to the map (manifold pressure) sensor?). Though if the trottle position (gas valve) is at 75% or more, the driver wants rather power than fuel economy, and the system drops lambda to 'maximum' 0,8 using i guess map-sensor, rpm and trottle position. Lower than 0,8 does not gain power anymore says the book.

So does leaner mixure really gain power? I still see no reasen to make it leaner than 1.0 cause it's more dangerous and won't gain power only economy.

Another question that comes to mind is how can an o2 sensor even accuratly monitor rich lambda mixures (under 1), because in rich mixures you are supposed to have zero o2 at the output?

Practically, I guess the first step is buying something like this fuel/air gauge + sensor (350 usd):
http://cgi.ebay.com/ebaymotors/Auto-Meter-2-1-16-Sport-Comp-II-Wideband-Air-Fuel_W0QQcmdZViewItemQQ_trkparmsZ72Q3a543Q7c66Q3a2 Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a0Q7c293Q3 a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem 250351094826QQitemZ250351094826QQptZMotorsQ5fCarQ5 fTruckQ5fPartsQ5fAccessories

When I got this properly installed, I can read the lambda or mixure value at any time while driving (although i dont yet understand how it can measure rich values...).

The information i can get from this device is:
- air/fuel mixure dependant on trottle position (and rpm?)
- find trottle position were stock o2 sensor gets out and mixure is going riche (WOT).
- minimum and maximum air fuel mixures

I can use these values to:
- adjust the map-sensor output (with per example a safc) so that in higher trottle positions (WOT) I get up to 0.8 (11.8:1) mixure for maximum power (in the assuming that the stock ECU is not getting the mixure up tot 11.8:1).
- any other applications?

Big question about that to me is 'how low can you go'? Maybe the stock engine already goes to 11.8, maybe 11.8 is allready to low... how can i check on which point i'm not gaining any more power by adding more fuel, are there any restrictions to find for this motor. Can i see this while driving and adjust the safc until i got point of maximum speed with a constant 75% trottle position? Aren't that speeds like 150 mph? I guess the dyno really is necessary? And when that comes to mind the wideband o2 sensor becomes unneccesary cause than i can find the optimal power point without it... : s

I know this is a lot of questions which to me are very interesting. But it's also stupid to buy a 350$ gauge and a 500$ fuel controller if you don't know what exactly to do with it or HP gain can be zero.

MrTurrari
01-03-2009, 10:29 PM
Sorry this is going to be a little long winded but I will try to answer your questions as best I can.

The design of the engine plays a huge part in where the best power A/F will happen so there is no single number you can shoot for that applies to all. Newer pent-roof chamber designs like the 3sge tend to like leaner mixtures because they do a better job at mixing and burning the fuel and dealing with the heat generated by the leaner burn. Older engines such as pushrod V8s and 2 valve per cylinder motors required more fuel because the burn was not as efficient. Because of that they also required more timing advance to give the mixture time to burn. 14.7:1 is the point where if everything were perfect, all the fuel and all the oxygen would be used during combustion but that never happens in the real world. If they could get a perfect burn in an engine that could survive the heat under high load then 14.7:1 would actually provide the most power. But the burn is never perfect and on some engines it is worse then others.

For cruising or low load situations when less heat is being generated the ECU will try to keep it at 14.7:1 using the O2 sensor. Narrow band O2 sensors read a scale which only allows for a higher/lower kind of reading in reference to 0 lambda. They really can't do anything else accurately but they work for closed loop like this. That mixture gives you (just about) the most energy for the amount of fuel being burned and since you are not creating gobs of heat the engine can handle it. You can actually get a little better gas mileage at slightly leaner then that because not quite all the fuel is burned.

Now when you put a high load on an engine you are suddenly creating a lot of heat and because you can never get a perfect mixture you need more fuel then oxygen. That's because when things get hot enough, if there is too much oxygen and not enough gasoline it will find another fuel to burn, like the aluminum in the engine. So the extra fuel cools the charge and makes sure there is always plenty of fuel for the oxygen to pair with. If you have an EGT guage you can actually see the temps drop when you go into WOT as it adds more fuel. Leaner mixtures do in fact make more power up to the point where detonation starts to take it away again. So it is really a balancing act where you are trying to get the most power vs the engine eating itself or being hammered to death by detonation.

Now engines that have to run richer mixtures to get better power most likely have worse chamber designs that create lean spots, heat buildup or too much timing advance that leads to detonation at AFRs that other engines would have no problems with. So the reference you mentioned may very well be true for that one engine but there are just too many factors to say it will be the same for all. Each engine design will have its strengths and weaknesses and the tune needs to match them. The optimal AFR will even change with RPM and what gear you are in.

My personally experience with a similar NA pent-roof engine (built 5sfe) is that to be safe at WOT you want to be in the 12:1-13:1 range. A little richer is ok but I noticed no difference in power (butt dyno only). I found a noticeable power increase though up at 14:1 but I wouldn't recommend running that lean unless you build your engine to handle it and then probably only for short durations.

The link you posted is a wideband O2 sensor which accurately reads a range of mixtures unlike a narrowband which is only good at telling you a reference to 0 lambda. There are cheaper ones out there though and for that price, maybe a little more, you could get one that logs and monitors other stuff like the Zetronix or Innovate. An O2 that logs wins hands down for tuning on the street. There is just no way for you to safely pay attention to everything.

Basically if you are looking to eek every last hp from you current setup then you need a dyno or track time to actually measure gains when you make changes. If you are just trying to correct the AFRs as you add new mods to keep it safe and get close enough to the engines power potential then a wideband and piggyback will do just fine.

djorkaef
01-04-2009, 01:52 AM
Thanks it really is a pleasure for me reading this texts.

Actually what you saying is like the 3sge is an injection motor which is properly designed to get power out of lean (hot) mixures @ 14.7:1? The only reason the fuel gets richer at high trottle is because of the heat that can't get away and so the exta fuel cools down the engine plus makes sure the oxigen won't react with the aluminium and decreases the changes of detonation (event @ high temperatures).

Because of the temperature drop and decrease in volume you actually might lose power if it's too rich. So actually you want to keep the temperature at the save level, as well as mixing it as lean as possible. Right?

So that EGT gauge would be very usefull? Because that's the only way to see whether temperature is at normal level or not.

Regardless to that, i'll tell you what the plans are (not that much plans...):
- K&N 57i cold air intake
- Sebring exhaust (the model that 'fits' with celica t18 2.0 on their website)

These things normally increase hp, but as you say they might have (big?) influence on the fuel mixture (getting it to rich or unsafely lean, but can it really change the stock mixure like from 13:1 to 12:1??). Thats where to use the afm and safc for. If i dont have this temperature sensor, it's only guessing how lean i can get it (using youre 'experience' 12:1-13:1 range for a 5sfe). Because I refuse to get any 'experience' detonating or burning my motor.

You say 'trying to correct the AFRs after modifying', than maybe I should measure the current mixures and make sure the mixures after modifying are the same.

MrTurrari
01-04-2009, 08:01 AM
Actually what you saying is like the 3sge is an injection motor which is properly designed to get power out of lean (hot) mixures @ 14.7:1? The only reason the fuel gets richer at high trottle is because of the heat that can't get away and so the exta fuel cools down the engine plus makes sure the oxigen won't react with the aluminium and decreases the changes of detonation (event @ high temperatures).
That is the basic jist of it. Combustion is a controlled explosion. More violence equals more power but your engine needs to be able to survive it. There are some other discussions that might interest you if you want to know more... look for one on "boundary layers" here on the board. I learned a ton of new stuff in that thread. :laugh:


Because of the temperature drop and decrease in volume you actually might lose power if it's too rich. So actually you want to keep the temperature at the save level, as well as mixing it as lean as possible. Right?
Actually the temperature drop is a plus and gets more mixture into the cylinder but in the end it is the amount of fuel and air that is combusted that counts and not only is it important that it burn but it must burn at the right time. It's too complex to rely on only one reading like EGT or AFR to determine if you are getting best power. I wish there were some hard and fast rules like that but it is a dynamic system. It definitely is a good idea though to see what your engine is like stock so you can use that as a base as to what is normal. For example I used to see stock EGTs in the 1400-1500F range but once I dropped compression to 9:1 and installed cams I never see anything above 1300F cruising and 1200F at WOT. AFRs are about 13:1 so it is not an indication of a rich mixture. It is actually an indication that cylinder presures are lower which is ok because I plan to turbo this motor. Once I add forced induction the temps should be up in the 1450-1550F range.


So that EGT gauge would be very usefull? Because that's the only way to see whether temperature is at normal level or not.
EGTs can give you a lot of useful information. I am not an expert on that though. I do know that detonation is often seen as a sharp drop in EGTs if your sensor can pick it up. Also I know that you don't want them ever to get to 1600F with aluminum heads.


Regardless to that, i'll tell you what the plans are (not that much plans...):
- K&N 57i cold air intake
- Sebring exhaust (the model that 'fits' with celica t18 2.0 on their website)

These things normally increase hp, but as you say they might have (big?) influence on the fuel mixture (getting it to rich or unsafely lean, but can it really change the stock mixure like from 13:1 to 12:1??). Thats where to use the afm and safc for. If i dont have this temperature sensor, it's only guessing how lean i can get it (using youre 'experience' 12:1-13:1 range for a 5sfe). Because I refuse to get any 'experience' detonating or burning my motor.
For those mods I wouldn't worry about it. Intakes and exhausts will have very little effect on AFRs because the relative vacuum doesn't change much for a given air flow. People certainly have eeked out a few more HP by tuning the stock maps with a piggyback though. The kind of mods that I was refering to that really benifit from tuning are those that significantly change the VE curve of the motor (ie cams and turbos). Sorry I didn't mean to imply that all mods require it to be safe.


You say 'trying to correct the AFRs after modifying', than maybe I should measure the current mixures and make sure the mixures after modifying are the same.
That is exactly what I did when I installed my cams. I first figured out what things looked like stock and then after the cams were installed made the curve look the same so it was holding a smooth AFR up the revs.