The Free Mod Series - Part III Taking Advantage of Intake/Exhaust Upgrades

[Toysrme]

Background:
So now we've done basic Intake and Exhaust upgrades, but are we taking advantage of it for it's fullest extent? No! Even if we've added next to nothing in power, we can still add a bit more power, and improve throttle response.

The stock ECU's are programmed to run as close to 14.7-1 Fuel Air ratio as possible. This is great for fuel economy and emissions. The drawback is that this ratio is not good for making power, or throttle response. It's too lean. For a N/A engine, we really want October to a 13.5-1 air-fuel ratio.

Theory
We need to add fuel to the mixture.
We've all seen the cheap-o Ebay "gain 22hp engine chips" that sell from between $5-$25.

They work by adding resistance to the I.A.T. Intake Air temperature sensor to make the ECU think the temperature is colder than it really is, in response it will richen the mixture.

The Problem
They don't work on Toyota's as discussed many times before. The ECU isn't fooled for any length of time before it reverts back to normal tuning.

The Solution
The intake air temperature sensor signal isn't the only one that can easily be modified so that the ECU changed the fuel mixture.

Enter the E.C.T. Engine Coolant temperature sensor. By placing a 500 ohm resistor on the ECT sensor wire going to the ECU, we can control what the ECU thinks the coolant temperature is.
By RAISING the resistance on the potentiometer, the ECU thinks the coolant temperature has dropped. In response it not only adds the corresponding amount of fuel, it advances the timing slightly as well!

Instructions
After buying a 500 ohm potentiometer from an electronics store <cough> Radio Shack <cough> electronics store <cough>
Obviously this is a very simple mod, but many will shy away from it because you have to find the wire going from the sensor to the ECU.
Trust me in that if I can wire an 11 wire SMT-6 and tune it with no instructions, or help (and I'm the only one on earth anyone knows of woot!). You guys can cut one wire and solder a dial in.

I suggest looking in whatever manual you have. Toyota, Lexus, Hayes, Chilton. Don't count one book out. They're all equally incorrect on ECU wiring, simply because the wiring can change on what seems like a random basis from one day to another.
Just find the ECT marking on the diagram, and look at which wire it's on.

Tuning
This is how tuning should proceed.
Obviously everyone's potentiometer will adjust at a different rate. Start with the potentiometer turned off 0-resistance. Crank the car. Then turn the knob slowly until your RPM rasises in 100rpm increments.
The greatest performance increase should be with your idle raises somewhere between 950rpm and 1100rpm. Most will probably split the gains between 1000rpm-1050rpm.

Results
This isn't going to give you a huge amount of power. What it will do is advance the timing between .5 and 2 degrees, and add 2-4% extra fuel to the injectors.
It's not much, but we're talking a $2-$3 part and less than 15 min of work.

*note*
The engine reporting a lower than normal temp will not affect the engine's ability to shift the transmission, or rev freely. In the unlikely event you bought the wrong resistance potentiometer and it happens... Turn the dial the other way, or get a 500 ohm potentiometer!




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Other Articles in the Series:
Part I Quicker Transmission Shifting
Part II Adding Airflow
Part III Taking Advantage of Intake/Exhaust Upgrades
Part IV Cheaply Monitoring the ECU & A/F
Part V How to pick up MPG, and sleep with her too!
Part VI Acing Aerodynamics
Part VII Cheap Water Injection
Part VIII Electronic Transmission Controller
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[Toysrme]

For the guys that know how ECU's work. Don't bring up closed and open loop mode. The mod works in closed loop mode, so don't bring it up and confuse the newbies.

The ECU also never disregards, or has a way to "learn" the mod. Cold sensor = cloder ECU map in closed loop. Cold sensor = different open loop tune.

[alex86]

dont exactly have a manual at hand got any place that might have that i could just look up w/o buying it or might have one for an 88 camry?

[userlain]

the gain you would be getting would be so minimal, its not worth the time.

the only benefit i could see would be timing advancement, but that is really easy to do anyways.

nice writeup though

[MadDawg]

ok, if you will not notice hardly if any HP gain from this mod, then whats the point in screwing up your gas mileage?

[SSC]

Originally posted by Toysrme
For the guys that know how ECU's work. Don't bring up closed and open loop mode. The mod works in closed loop mode, so don't bring it up and confuse the newbies.

The ECU also never disregards, or has a way to "learn" the mod. Cold sensor = cloder ECU map in closed loop. Cold sensor = different open loop tune.

Well I'm attempting to understand your wording here. "I'm the one who confuses people"

By doing this mod you will prevent the ECM from reaching closed loop and send a constant extra flow of fuel into the mix the ecm will not be able to adjust for. The ECM only has a set amount of timing in open loop to prevent engine damage since it does not see all the sensors. This extra fuel could lead to fould plugs and a plugged cat which would negate any benift from this mod.

Of course the same could be said from any engine mod that the ECM cannot compensate for. This is the reason tunnning with the ECM is so critical (prom burning ect..)

If it does show improvemnt that can be backed by track times or on a dyno it would be a great mod for short period period use. I just cant see it.

[Toysrme]

By doing this mod you will prevent the ECM from reaching closed loop and send a constant extra flow of fuel into the mix the ecm will not be able to adjust for.

No, by doing the mod the ECM uses a different closed loop map. That particular map will richen the mixture depending on how "cold" the fluid is.

The ECM only has a set amount of timing in open loop to prevent engine damage

Correct. What you're missing is that the ECM in open loop mode will run the same timing. It is not affected. (timing is closed loop only, and under no more than 2,500rpm. We're also talking less than 2 degrees of timing advance at any setting so stop worrying about that) The engine has knock sensors... There is also a major room for timing advance depending on the RPM range on the earlier v6's. 2vz/3vz.

Like I said...

Don't bring up closed and open loop mode.

The reason is beause we wind up with confusing conversations (what we're doing now) to people that don't know how an ECM works. I also can beat down any arguement on it.


About fuel. It takes it to make power. Re-read the *Background* section to find out why this mod is worth the time . This mod will give the best performance with the ECM "thinking" the temperature is between 150F and 170F.

The amount of fuel this mod can apply is rather astonishing. It can raise the short term fuel trim 6%, and can move the long term fuel trim 2%. That's a lot of fuel for a $2-$3 part. If you dial it in to 1050rpm at idle in Park or Neutral, it will add 4% fuel short term, and will eventually add 1% fuel to the long term fuel trim.

[SSC]

I'll give it a test run and see what happens. But its getting so freaking cold uo here I doubt the ECM will even get out of open loop.

[Toysrme]

Don't worry when you try it. You have to make the ECM think the coolant is around 120F-130F before it limits the RPM and won't shift down. Don't worry about it.

The idle will be the same in a gear, but in Park or N it will raise the more you increase resistance. (turn the knob) You'll know you've turned it too far (and realise how muhc fuel you can add!) when the engine responce goes from a little better to worse.

I'm doing this because I know a million little tricks that might add a hp or a maybe a few for no-very little cost.
I could easily tell anyone that wanted 200hp out of a 3vz-fe to cut a hole in their airbox and go buy a $300 SMT, richen the fuel until the last two vertical rows (where you need to lean on the top half), build a relay(cause the 6 is finiky with ignition signal changes) and advance the timing from 3 points off idle to 8-12 points in high RPM-WOT TPS/AFM/MAF/MAP setting.

It's easy to make 5-20hp for a few hundred bucks. my thing is that most people on Toyota Nation are not willing to spend $400-$500 on upgrades that won't get them 20hp.

I'm trying to give the tight wads some options!

[superg3]

I wouldn't mind giving this a try. I don't have a manual for me to look up which wire it is. Anyone have info on 94 4cyl camry manual ecu?

[88 LE]

Originally posted by alex86
dont exactly have a manual at hand got any place that might have that i could just look up w/o buying it or might have one for an 88 camry?

http://www.autozone.com/servlet/UiBr...ginRepairGuide

Originally posted by superg3
I wouldn't mind giving this a try. I don't have a manual for me to look up which wire it is. Anyone have info on 94 4cyl camry manual ecu?

See link above.


Heres a picture of the ECT (engine coolant temp) sensor on my 3S-FE:

[superg3]

I haven't looked under the hood yet but , how do you wire the pot? It has three prongs right? And how many leads are coming out from the sensor, if there are two, which one do I choose unless there's only one.

[Toysrme]

Bump

[superg3]

hey is this for automatics only?

[SmokingTires]

Originally Posted by userlain

the gain you would be getting would be so minimal, its not worth the time.

the only benefit i could see would be timing advancement, but that is really easy to do anyways.

nice writeup though

Noob

Advancing your timing requires more fuel, or higher octane. And adding more fuel to the mixture by that amount gives a good boost in power. More than your little intake did.