Does this IAC reading sound correct to you?

[bishir]

At startup my IAC reads 40 on the scanmaster. I noticed today that after the car warmed up it went up to about 42 and stayed there almost the whole time while I was driving home. Does this sound normal? At startup my TPS is .38 which is lower than the recommend .42. Could that have something to do with it? I didn't think so because the IAC never seems to move much. BTW, the car will usually die once if I put it in drive after about 15 secs of warmup. Is this because the TPS is too low? It will idle at around 700-750rpm.

Thanks,

James

 

[BoostedBug]

IAC in park should be in the low 20's to the high teens. The tps is off also. Try turning the air screw in on the throttlebody to lower the iac's. When you do this your tps will drop also. Turn the airscrew in some then check the tps and adjust it. Crank the car and watch the IAC. When you get it down to the low 20's to high teens it will run allot better. Your tps should be .42 key on engine off. When you crank it it will go up to .45. After you get this set right go back and check and make sure that the tps is at at least 4.60 wot key on engine off.

 

[bishir]

Thanks for your reply! I will adjust the settings once the car is back from the transmission shop.

James

 

[TurboDave]

Never read any IAC numbers at anything but 0 (zero) mph (parked). Trying to read them while the car is moving is pretty meaningless, unless you're totally familiar with the car's "normal" readings while moving. And even then they're of no practical use.

Only read IAC after the car's warmed up and while in park or in gear, but never moving.

 

[bishir]

Thanks for the reply. Can you explain to me what IAC means and how it's measured? Also, do I need to include any other information like weather? It was probably low 40s the day of the readings.

 

[TurboDave]

IAC is Idle Air Controller (sometimes called Idle Air Counts). There is an IAC controller mounted on the bottom of your throttle body. This device is how the computer sets and controlls the idle rpm. It is a way to bleed air around the throttle plate (for higher cold start rpm for example).
This device has a plunger in it. The plunger is electronically moved in or out, to allow less or more air to pass. More air=higher rpm.

This is why there is NO provision for mechanically adjusting the idle rpm.
Those that tell you there is are fooling themselves. That little screw near the top of the throttle body is for setting the minimum air bleed. Primarilly it is used to monitor the IAC at idle, and adjusting it, can get these numbers to their optimum setting.
Basically, when the car is fully warmed up, and in park/nuetral, you should be seeing IAC numbers anywhere from 10-40.