another idel question/problem ....please help

[89blkvet]

when i start my 89 (cold) it idles VERY smooth, sure a little high due the cold, but when it gets to opeating temp, 175 plus, the idle is horrible, it jumps all over the place. I tried to adjust the TPS, no sucsess.....it seems fine for a while, then again, it's all over the place. Am I missing something here.....help !!

 

[Magmotor]

Idle speed can be affected by:

1) Park/Neutral switch- If ECM thinks the car is always in neutral, then idle will not be controlled to the specified rpm.
2) Leaking injectors will cause fuel imbalance
3) Vacuum or crankcase leaks
4) When the throttle shaft or throttle position sensor is binding or sticking in an open throttle position, the ECM doesn't not know if the vehicle has stopped and does not conrtol idle.
5) Check A.I.R. management system for intermittent air to ports while in "Closed Loop". There should be no A.I.R. to ports while in "Closed Loop".
6) Examine the EGR valve for proper seating
7) Faulty battery cables can result in voltage variations. The ECM will try to compensate, which results in erratic idle speeds.
8) The ECM will compensate for A/C compressor clutch loads. Loss of the A/C request signal would be most apparent in neutral.
9) Contaminated fuel
10) Perform injector balance test.
11) Check ECM ground circuits
12) Check voltage output: not less than 9v
13) Run a cylinder compression check
14) Inspect O2 sensor for silicon contamination
15) Check for fuel in pressure regulator hose. If present, replace regulator
17) Disconnect MAF sensor. If conditions is corrected, replace sensor.

Do you have a scanner or access to one? If so, monitor the "block learn"

 

[89blkvet]

where would I get a scanner and what other things would it tell me, TPS voltage?.....timing?.....etc? thanks

 

[Magmotor]

where would I get a scanner and what other things would it tell me, TPS voltage?.....timing?.....etc? thanks

There are quite a few on the market. You can do a search here or on Google..I use 'Ease'....on my laptop....It does save a lot of head scratchen....

 

[Midnite 88]

Have you cleaned your IAC valve lately?

Mike.

 

[89blkvet]

No I haven't, how do I do that???????

 

[Midnite 88]

There is a Tech Tip on another forum that explains it in detail. If you want to E-mail me directly I can point you to it. It is a pretty involved process because you have to reset your TPS which is a process in itself.

midnite88@att.net

Mike.