Idle problems

[MarkieSHO]

Sup guys, right to the point , at times when car is at idle the revs bounce up and down , between 700rpms to bout 1100 rpms or so, and if it aint doing that, it revs high to like 2500rpms and stays there, this has been happening a lot lately, and i wanna know what the heck is the problem, thanks for your input

 

[DavidT]

me too...

 

[97V8SHO]

I found this on V8SHO.com

Idle Air Trim

Idle Air Trim is designed to adjust the Idle Air Control (IAC) calibration to correct for wear and aging of components. When engine conditions meet the learning requirement, the strategy monitors the engine and determines the values required for ideal idle calibration. The Idle Air Trim values are stored in a table for reference. This table is used by the PCM as a correction factor when controlling idle speed. The table is stored in Keep Alive Random Access Memory (RAM) and retains the learned values even after the engine is shut off. A Diagnostic Trouble Code (DTC) is output to indicate that the Idle Air Trim has reached its learning limits.

Whenever an IAC component is replaced or cleaned or a service affecting idle is performed, it is recommended that Keep Alive RAM be cleared. This is necessary so the idle strategy does not use the previously learned Idle Air Trim values.

To clear Keep Alive RAM, refer to «PCM Reset» in Section 2A («Section 2B», Diagnostic Methods for 1.3L Aspire and 2.5L Probe). It is important to note that erasing DTCs with a scan tool does not reset the Idle Air Trim table.

Once Keep Alive RAM has been reset, the engine must idle for 15 minutes (actual time varies between strategies) to learn new idle air trim values. Idle quality will improve as the strategy adapts. Adaptation occurs in four separate modes.

 

[SHO#7]

I had a similar issue once I took the car out of storage for the winter. I removed the IAC valve, and cleaner her out. Re-installed, and all problems went away. There was alot of carbon built up inside the valve. Hope this helps you. In either case, good luck.

 

[MarkieSHO]

Ill give it a try, where exactly is the IAC thingie? a picture would be most helpfull

 

[SHOZ123]

On top of the throttle body, the cylinder shaped thingy.

 

[Wess]

IAC IAC IAC

They tend to stick, get it replaced or hit it with a hammer

 

[MarkieSHO]

this weekend it will be done, thanks for all the replies

 

[wuzzzer]

I had the same problem just after I bought my SHO 3 1/2 years ago. At first I thought "oh great, this one's going to be just as crappy as my Gen 2 was."
Then I read about unplugging and plugging back in the TPS connector:
I did it a few times just to make sure it made a good connection, and I haven't had any problems since. It's worth a try, simple and easy fix if it works!

 

[DavidT]

as far as cleaning the IAC... would you basically follow the same guidelines as for the v6?

 

[MarkieSHO]

It Worked!!! Many thanks