IAC Adjustment ?????

[Whistle Pig]

I am in the process of trying too get the iac then tps set with a scanmaster. I cannot get the crosscounts to go up without running 3000 rpm ( I am rookie) Does this motor go bad? It idles about 1400 rpm with 7 for a crosscount before I had my way with it! ???? Help ? Tia Kevin
I have been trying to follow turbo tecks method too no avail!

 

[TurboDave]

Originally posted by Whistle Pig
I am in the process of trying too get the iac then tps set with a scanmaster. I cannot get the crosscounts to go up without running 3000 rpm ( I am rookie) Does this motor go bad? It idles about 1400 rpm with 7 for a crosscount before I had my way with it! ???? Help ? Tia Kevin
I have been trying to follow turbo tecks method too no avail!

If you're looking at "cc" (crosscounts) then you're looking at the wrong data field. Crosscounts are for O2 crosscounting.

You need to be looking at IAC's

I like to keep mine set for around 15 or so while in park, idling, warmed up engine of course.

 

[Whistle Pig]

Dave I am looking at the iac, I thought I read too the count as being referedtoo as crosscounts? I am lost here! Is this supposed to be adjusted by the throttle screw? It mention a cable with grey plastic ( not found) I tried by moving the throttle plate but got 3000 rpms instead?

 

[OKTurbo]

Like TurboDave said...the crosscounts tell you how active the O2 sensor is. It doesn't tell you anything about the IAC.

When setting the IAC you look at the IAC#'s and the TPS voltage. You adjust the throttle screw until you get a IAC # between 15-30 at idle. Make sure the car is warmed up.

If you have to move it much you will also have to tweak the TPS sensor to get an idle TPS voltage of .40-.45.

Everytime you move the throttle screw you'll also change the TPS setting....so you have to go back and forth until you get it. It's best to turn the car off after each change....and then restart it to check it out.

BTW....the idle speed is controlled by the computer.

Have fun,
John

 

[Whistle Pig]

Ok IAC It IS!

John the problem I am having now is the car is idling at 2000 plus rpm before the Iac goes up to around ten? Basicaly I cranked it till the spring was compressed? I put it back to where it was for now and have nothing showing on the scanmaster till I step on the gas pedal? I may be in over my head but it sounds easy enough? I am not sure what I am doing wrong? Just went for gas and left it running, while I put 10 gallons in I watched the scan mas. go from mid 50's down to 0 ? TIA Kevin

 

[Steve Wood]

There is a possibility that the iac needs to be replaced...but first.

What is your tps voltage at idle, engine running? It must be .46 or less.

Secondly, with the car fully hot, idling in Park, AC off, what are the iac counts, they should be pretty steady and in a range between say, 15-40.

If they are not, unscrewing (counterclockwise) the iac adjustment screw will increase the numbers. That will also lower your tps voltage. If the numbers are too high, turning the screw clockwise will decrease the numbers and increase the tps voltage. If it goes above .46, it will cause a fast idle. After an adjustment, kill the engine and restart to reset the iac...see if it stays where you want it. Don't let the tps go over .46 and I prefer to be at .44 or less, to provide some margin of error.

It would not hurt to remove the iac and clean it with carb cleaner along with the passages into the throttle body before you start. Do not overtighten it, just snug, so you don't crack the plastic housing.

 

[Whistle Pig]

The tps is at .42 engine running,closed loop ,165 degrees. When you say adjust the iac am I correct that you are refering to what would be on the throttle plate? Thanks Steve

 

[Steve Wood]

yes, that is the idle air control screw. Basically, at idle on our cars, the throttle blade does not control the idle. Rather it the iac solenoid bypasses air to maintain a constant idle under varying loads. If you screw the screw too far in it will suddenly kick the idle up as it moves out of the iac's range.

 

[Whistle Pig]

I will try cleaning that tomorrow! Looks like about a 1 inch wrench? With this setting so far of would it cause a lean problem or is this where the integrator would compinsate? Sorry for all the questions. Kevin

 

[OKTurbo]

Kevin,

It looks like Steve is getting you going in the right direction.

There's some good info here http://www.geocities.com/rad87gn/tech/IACTPS.html

The tps or iac being whacked out won't really cause a lean condition. You can look at your idle BLM and INT values to check for that. Lean idle is usually caused by a vacuum leak somewhere. If the BLMs and INTs are close to 128 you're OK as far as fueling is concerned. BLM/INT numbers above 128 mean that the computer is ADDING fuel....therefore you are getting unmetered air (lean)....numbers below 128 mean that the computer is taking fuel out (rich). The BLM is a "long term" fueling correction and the INT is a "short term" correction.

There is some variance in the BLM/INT that is OK.... 110-140 is probably OK. The "magic" number is 128.

You didn't mention your MAF numbers at idle. MAF should be 4~6 at idle. Bad MAF sensors have been know to make for a crappy idle.

Just another quick tip. You'll know when the computer has gone into closed loop when the decimal point on the scanmaster has stopped blinking.....basically means that the car has warmed up enough for it to read the MAF sensor and O2 sensor and make "automatic" fueling corrections.

It all seems pretty overwhelming at first, but you'll get it soon.

Good Luck,
John