Question about 1990 Mercury Grand Marquis
1990 mercury g/m-5.0L-V8-EFI, mileage-86,000mi, Ignition & fuel systems appear OK. No service light,no codes. After restart at high speed idle ,engine will reduce rpm & continue to operate ,but at times will stall unless accelerator is depressed to maintain rpm. After warm-up engine is OK. Cold start is the issue. Please help. Thank you.
I had a similar problem. I found the filter cartridge below the pcv valve had carboned up, and after the crank case pressurized, oil was forced out the pcv supply line to the throttle body. The idle air control valve solenoid got oil in it and caused my problem, but only when it was cold. The pcv cartridge is accessed by removing the pcv valve and the rubber fitting that the pcv valve mounts in. It can then be fished out with a pick set, and it is a pain because you can't see it, but you can get you hand back there. I hope this helps you.
Posted on Feb 28, 2009
Well the first thing that comes to mind is the idle air control valve located on plenum/throttle body. that valve controls the air flow to engine when its at idle. could remove, clean shaft with carb cleaner and lubricate. and see if that makes any difference. valve may need replacing but this is a good test
Posted on Dec 07, 2008
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