Q: Rough idle and RPM fluctuation

asked by on December 17, 2016

So here is my issue I was on my way home last night and the roads were slick and I was sliding quite a bit and all of assuden my truck started to want to die and at every stop sign I would have to restart my truck when it does idle it idled at like 500rpms sometimes lower and when you let off the gas while driving or just in park it will dies most of the time I hooked it up to a code reader and the only code I found was an issue with the map sensor so I replaced the map sensor but I'm still having the issue

My car has 185000 miles.
My car has an automatic transmission.

Hi There, As you may know, the Manifold Absolute Pressure (MAP) sensor senses engine load and generates a signal that is proportional to the amount of vacuum in the intake manifold. The engine computer then uses this information to adjust ignition timing and fuel enrichment. When the computer reads a heavy load signal from the [MAP sensor]((https://www.yourmechanic.com/services/manifold-absolute-pressure-sensor-map-sensor-replacement), it adjusts the fuel mixture to slightly more rich than normal so the engine can produce more power. The computer will then retard (back off) ignition timing slightly to prevent detonation (spark knock) that can damage the engine and decrease performance. This may also be caused by other closely related components such as a dirty or failing mass air-flow sensor, a faulty throttle position sensor or potentially a vacuum leak.

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