DTN

You are right. Without a barrier, it could potentially fry the ECU. I will eventually hack the ECU to figure out a tuning solution which is permanent. I'm telling you that it is possible. The MAF is the course adjustment and the IAT is the fine adjustment.

radu_rd2

Who needs fuel and ignition maps when you can have.. two knobs!!

krazytib

On my car I slapped a 5k ohm potentiometer in between the wires that go between the IAT sensor and the ECU so I can increase or decrease outside air temps. I then ran wires into the car and installed the knob under my stereo allowing me to change the outside temperature on the fly to what ever I want the ECU to use in its calculations.

Have you ever been stuck in stop and go traffic and watched the IAT slowly raise in temperature and before you know it, its reporting the outside temperature 20 degrees warmer that it really is outside causing your cars performance to noticeably degrade. As you release the clutch the car bogs down more and more as the temperature raises.

Now with the adjustable IAT, all you gotta do is turn the knob and lower the outside temp and no more bogging down. By making it colder outside you are increasing the fuel trims thus burning more gas. So from some tests I have done, depending on how much over or under the ambient outside air you keep the setting at can result in around a 4mpg difference per tank. So if im low on gas I make that IAT tell the ECU its like 20 degrees hotter than it really is till I make it to a gas station then turn it back down to get the performance back. Changing the temp even has an effect on the sound of my exhaust. When I raise the IAT value to outside air temp or hotter I can get a slightly different tone from my exhaust when I get off the throttle completely.

By using the potentiometer you have way greater control compared to a static resistor which could hurt performance in certain conditions.

I have never payed attention to load calculations with this mod but I will look into it. I have noticed that I can get my long term fuel trim values to change by increasing or decreasing the outside air temp.


I wonder if this could be beneficial during a smog test to lean the car out if you ran too rich. cool.gif



This is the website with a great write up on the adjustable IAT that I used for reference when building mine.

http://autospeed.com/cms/A_110896/article.html

They also have other articles for modifying other sensors.

Here is an article that talks about modifying the MAF sensor.

http://autospeed.com/cms/A_109134/article.html

DTN

Hey, that's what I was missing. A balance pot. Basically this is the same as the one that I posted, but the first potentiometer allows you to specify the load value and the second allows you to specify the control value.



<div class='quotetop'>QUOTE (radu_rd2 @ Mar 14 2010, 06:44 PM) <{POST_SNAPBACK}></div><div class='quotemain'>Who needs fuel and ignition maps when you can have.. two knobs!!</div>
Exactally. Use the stock maps and modify what's going in.

krazytib

<div class='quotetop'>QUOTE (DTN @ Mar 14 2010, 04:44 PM) <{POST_SNAPBACK}></div><div class='quotemain'>Exactally. Use the stock maps and modify what's going in.</div>

I also have some 10k ohm pots that have a bypass feature where you can turn them off which would allow the original current to go right by putting the sensor back to stock values. It just requires a little extra wiring.

Im curious as to how much more power I can squeeze out of my car with sensor modifications. The MAF mod does seem interesting. I was also thinking about about testing a pot inline with the coolant temp sensor to see if or how much of a difference that could make since it also affects the ignition timing.

Let us know if you get something working.

David Dickson

LOL, why not just get a piggyback ECU that can compensate for air and coolant temps? I just had a vision of someone driving around with a ton of pots taped to his arm and constantly adjusting them to get peak power. Makes me want to take up smoking pot...lol

likeyoumeanit

lmao.gif