Bad map sensor?

STEVE87

MEMBER
1999 DODGE CARAVAN

Attempted to test the map sensor because of poor idle and stalling when removing foot from accelerator and coming to a stop.I was using a digital voltmeter and a handheld vacuum pump. When I initially applied vacuum, it seemed to hold it at about 10 inches. But after that, it would always lose pressure rapidly.I checked to make sure all hoses and fittings between the pump and sensor were sealed as well. Does this indicate a faulty map sensor?

Monday, January 9th, 2012 AT 2:21 AM

1 Reply

CARADIODOC

MECHANIC
34,165 POSTS

I never took the time to test one that way, but yes, they should hold vacuum. If there has not been a related fault code set, the readings can be within the acceptable limits, but wrong. Just find a used sensor in a salvage yard and pop it in to try it. Unlike those from the late '80s that were supplied by GM and had an almost 100 percent failure rate, the newer ones don't fail real often anymore. With one common type of failure, the engine will continue to run, (poorly), as long as the gas pedal is moving.

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Monday, January 9th, 2012 AT 2:32 AM