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1988 Plymouth Other Repair Question


Topics covered: Rpm, Sensor, Spark.
Mileage: No information provided.

Asked on January 23, 2006

1988 Plymouth Sundance, Idle problems.

My car has been having trouble keeping a smooth idle. The car will start and then die immediately. If I hold down the gas for a few seconds and let go it will idle smoothly and I can drive it just fine. Sounds like the idle air control motor right? I get an error code confirming this so I took out the iac motor to see what would happen. The car should idle at about 3000 rpm. It doesnt. It gets to about 2000 rpm and idles erratically. After a few seconds it smoothes itself out and goes up to 3000 rpm and then dies. After this I get a code for the map sensor. This seems normal as with such an extreme vacuum leak it should tell me that something is wrong. Car has a new fuel pump and filter. Fuel pressure is fine at 14.5 psi. Compression is 135+ in all 4 cylinders. All 4 plugs are getting spark. I noticed that the brand new spark plugs I put in were covered with carbon (rich mixture?) so I changed the oxygen sensor. Fuel injector seems to be running smoothly as far as I can tell. Any other ideas?
Avatar Asked by Esgaroth

Answer

Replied on March 20, 2009

Hi:
Chances are there is a vacuum leak that you heven't found yet. Make sure there isn't a leak near the intake. Also, check the lines around the intake.

Let me know what you find. Just FYI, the idle should be around 900 RPM's.

Tiny Answered by Jacobandnickolas (expert)
57,318 answers provided