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Very fast idle, comanche pick-up

sperrylake

NAXJA Forum User
Location
sperry, oklahoma
My sisters 87 Comanche, 4cyl began idling very fast (2000 rpm) this week, undrivable. I ask around and have read the forum archives. The most common answer is the throttle position sensor. I replace it today and it still idles above 2500 rpm. What else on this vehicle do I need to investigate?

Thanks Bob
 
sperrylake said:
My sisters 87 Comanche, 4cyl began idling very fast (2000 rpm) this week, undrivable. I ask around and have read the forum archives. The most common answer is the throttle position sensor. I replace it today and it still idles above 2500 rpm. What else on this vehicle do I need to investigate?

Thanks Bob

Bob,

I don't know if the throttle bodies are in any way compatible in function... but when my 87 4.0L would idle too fast, I shut it off and wiggled the wiring cluster going into the front of the TB. I finally replaced it (the wiring link) and my high idle dissappeared. Seems that the wiring ground in that link was not grounding solidly anymore. You should check the FSM for the exact wiring display, find that ground wire and insure that it is within spec for the manual. I think when the ground is loose, the loop doesn't report the actual RPM of the engine to the ECM and therefore the ECM tries to compensate.
 
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