Idle speed on my 1987 Mercury Grand Marquis is going up and down - what' s wrong ?

135

Asked by Dec 18, 2016 at 05:26 AM about the 1987 Mercury Grand Marquis

Question type: Maintenance & Repair

When my Mercury is running for a while at idle speed, engine speed suddenly starts going up and down. Sometimes the engine even turns off after a few seconds. I checked all vacuum hoses - they seem to be OK. Can it be any sensor or valve causing this problem ? While driving everything is OK. This only occurs when enging is idling and the selector lever is set to "P".

3 Answers

116,665

Sounds as if the air idle control is defective or needs to be cleaned..

2 of 2 people found this helpful.
116,665

http://www.partsgeek.com/catalog/1987/merc ury/grand_marquis/fuel_injection/idle_control_v alve.html

1,545

Could it also be the TPS? (Throttle position sensor). They do wear out sometimes.

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