My cars IAC is maxing out at 160 steps upon start up. The IAC is brand new, and has already been reset using the instructions provided by shoebox. Once the car is warm, it still stays in the 80-90's. The throttle body blades are already cranked a bit open, and if I crank them open anymore, the idle raises. What else can I do? I really dont want to drill any holes on the blades. I also drilled a hole in the bellow behind the MAF, and ran a vaccum line from the bellow to the manifold, so that I get air into the plenum, but around the IAC. I also have lt1 edit..thank you..

 

Why the bypass for more air when you say the IAC is already providing too much?

If you were to crack the throttle blades a little more with the screw, your IAC counts should go down. Be mindful of your TPS readings if you open the tb blades some more.

 

thanks for chiming in Rob, very much appreciated. I was bypassing more air, because I figured that if the IAC is maxing out, the car is needing more air, at start up correct? If I crack the throttle blades anymore, the idle starts to raise. It idles at about 950-1000, and anymore, and the idle rises. As of right now my TPS readings are about .57.

 

Have you verified that the IAC passages are not plugged up?

 

yes, It is a brand new BBK 58mm TB.

 

What about opening the blades and then resetting the IAC again? You have to give it a little time to compensate.

 

The BBK throttle bodies have a problem with casting flash in the IAC passage. I'll ask again.... Have you verified that the IAC passages are not plugged up?

I've seen cases where people swapped the bottom plate on the TB, didn't gasket it correctly or possibly didn't tighten it correctly, and dripping coolant plugged the passages. However, you probably have already deleted the coolant.

 

Rob I will try that again. As for the passages, All I did was put a new gasket, and tighten the bottom piece. And yes Fred, you are correct, I already deleted the coolant from entering the TB. I will try to crank the blades open a bit, reset the IAC, and TPS. I will post back..Thanks

 

oh one more thing guys, what should the IAC counts be upon startup, and once warm? Thanks A Million!

 

Id try to set the IAC so it doesnt max out on startup but 100-150 is probably fine. Once the idle settles you should find the counts considerably lower. Basically as long as IAC doesnt max out on startup or when you turn on the A/C, anything is acceptable but "0". That is what I think anyway.

 

With your cam, you're going to see higher than "normal" IAC counts.

What did your programmer set for the idle speed? Adjust the idle screw slowly until you get the correct idle speed (per programmer's setting), then check the IAC counts. With a smaller cam you might be looking at 20-40 counts, but you might see 60-80 counts, depending where he set the idle. After you get the IAC and RPM right, check the TPS voltage. If the TPS voltage is above 1.00V (will set a code) at idle, you will get some elevation of the IAC counts, and it will screw up the coast-down engine speed. The idle TPS voltage should be between 0.20-0.90V to allow the PCM to baseline the 0% throttle position on startup.

Before doing anything to try and get the correct combination of idle, IAC and TPS, you might want to block off you added idle air paths. You should be able to control it without the add-ons, but a few people seem to need the extra air flow.

 

ok Fred, thank you so much..Im going out to do this right now..Will post results.!!