Vehicle does not idle smoothly. Engine speed will fluctuate +/- 500 RPM at idle. It also seems to occasionally misfire while cruising. There has been no check engine light, and no codes until I replaced the wiring harness (see below).
Around 6 weeks ago, the car would stall when ever I stopped. This continued for about 25 minutes, and then suddenly started working fine. Same problem occurred about 4 days later, and started working normally later that day.
November 27th, I replaced the leaking power-steering pump, and while I was at it, removed and cleaned the idle air control valve and replaced the connector at the wiring harness. Vehicle has been running great until December 9th.
Last weekend, I replaced all four spark plugs, re-examined the IAC valve, and checked the mass airflow sensor and the TPS. These components seem to be working within parameters.
This may be a “red-hearing”, but I have noticed that if I “jiggle” the wires leading to the MAF sensor, the engine will either “smooth out” for a few seconds, or it will stall. But I can’t do this with any consistency.
I have tightened the tension on the throttle cable to temporarily increase the idle speed to make the car “drivable” until this problem can be diagnosed.
I took the car to my local dealer. The mechanic apparently found that “the IAC circuit was open”, indicating a short and recommended replacing the wiring harness. I purchased and installed a new wiring harness and a new IAC valve, but the problem continues, and new problem has occurred.
The new wiring harness was apparently for a “California” car, and had a plug for an EGR temp. sensor. Now I’m getting a code 55 (EGR temp sensor). Is there any way I can just jumper this plug, or should I pull the pins on the harness plug where it attaches to the main bus?
Does anybody have any ideas as to what could be causing my idling / stalling problems?
Edited by jimbo747, 25 December 2010 - 09:56 AM.
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