At an idle my 88 GTA TPI 5.7 goes up and down between 500-780 rpm, and it makes this suckin sound when the rpm goes down, my friend said it could be the idle control valve...is this true?? and if so...how much? Thanks AARON

 

I don't have a solution for you, but I thought I would share that I have a similar problem. See my thread below

https://www.thirdgen.org/techbb2/sho...001#post836001

Perhaps it will help you.

All I can suggest, is check the basics .. plugs, wires, air filter, etc. Your typical maintenance. It seems that people have cleaned the idle air control motor with some success. Others found the MAF was going south. And I found one response about a fuel pump going. I'm sure each of those cases had a similar surge, but most likely other symptoms.

If you do find your problem out, please drop me a line. I'd appreciated knowing ... perhaps it will solve my surge.

Mark.
PS. If your web page is correct and your driver is a 85 S10 with a 350 ... you might find interest in my ride. Check out the www link below.

 

Aaron,
It could be your IAC valve. Here's what it says in a library book about the IAC:

"The IAC or idle air control valve mounted in the throttlebody is designed to control engine idle speed and prevent stalling due to changes in engine load at startup. It also provides cold start fast idle during the warmup period. A conical valve called a pintel moves in annd out against its seat to control the amount of air being bled past the throttle blades. If RPM is too low, more air is bypassed; if RPM is too high, less air is bypassed. The ECM moves the valve in small steps called counts. Engine idle speed is a function of total airflow calculations based on the IAC valve position, throttle valve opening, PCV flow, and calibrated flow loss to vacuum accessories. If the idle air adjustment is off it can be reset by stopping the engine. Depress the accelerator pedal slightly and start the engine for 5 seconds, then turn the ignition off for 10 seconds."