Idle still searching. Any ideas?

[AdvancedAutoCC]

Most times, the cause is a dirty IAC valve (pintle dragging in the bore), and/or the throttle body having an accumulation of sludge behind the throttle blades.

For the throttle body:
Pull the air intake off the throttle body, open the throttle blades and run your finger inside the throttle body. If it comes back with black gummy residue on it, it's a good bet you've found your trouble. Get some carb cleaner and plenty of rags and start to work on the throttle bores. You'll have to block the throttle wide open to be able to use both hands, but that shouldn't be a problem. Keep at it till you have a clane rag when you pull it back out.

For the IAC:
You'll have to remove the IAC valve from the side of the throttle body. Once done, take carb cleaner and a rag and clean off the pintle until clean. Spray carb cleaner inside the IAC bore and get something to clean the inside of same ( A gun brush works very well). Clean as with the throttle body. Reassemble and follow the factory procedure for resetting the IAC.

 

[Doktor-t]

iac

Cleaning the throttlebores is already done, only the IAC to go. Eastern holliday will be a good time to get some work done to the car

 

[Blue89]

I guess this would be in the same vain as this thread. Hopefully you have an answer. My 89 runs perfect when first started, smooth idle and all but when it reaches about 115 degrees the idle changes and sounds like it has the biggest cam in the universe, it's really erratic and doesn't change until cooled down again. It not only does it at a stop but while driving unless your accelerating. No codes. How about that one???

 

[c4c5specialist]

Hi there,
What is mystifying here, is that noone speaks of performing an minimum air idle reset on the engine. This is the first course of action, as every part being NEW does NOT make the engine idle correctly.
All of the point above are valid and are good point, but if the ECM DOES NOT KNOW where to set the idle air control valve, your idle will NEVER be correct and solid.
It will constantly hunt because it doesnt KNOW where to idle at.
If you have a GM service manual, the procedure is there.
Prerequisites include correct ignition timing, properly functioning fuel injectors and a sound engine mechanically.
Out of over 300 L98 with idle surge conditions that I personally have done, only 3 have required IAC valves or other parts.
Allthebest, c4c5:bang

 

[Doktor-t]

runs uneven

C4C5SPECIALIST maybe you can help me out, my car runs uneven and I´ve already started a thread on this forum, don´t know what to do with my car..


Tobias