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Q: Car is idling rough and missing

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My car is missing ,really bad, thought catilac converter was stop up the way it sounded and ran... It wasn't, so put new coil packs,spark plugs and wires on it still didn't help.. It spitting sputtering and has black soot coming out of tail pipes,and black smoke.. Has about all new sensors except for throttle position and map sensor, please help me on what it could be.. Thank you...

My car has 200000 miles.
My car has an automatic transmission.

A: This may be a sign of a faulty MAP sensor. ...

This may be a sign of a faulty MAP sensor. 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 engine is working hard, intake vacuum drops as the throttle opens wide. The engine takes in more air, which requires more fuel to keep the air/fuel ratio in balance.

When the computer reads a heavy load signal from the MAP sensor, 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.

I would recommend having an expert from YourMechanic come to your location to diagnose and replace your MAP sensor.

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