Q: While sitting at stop light, with foot on brake, engine revs as if someone else has gas pedal to the floor....pull into driveway a

asked by on January 07, 2017

also revving itself up going down the road now...automatic transmission sometimes bucks and jumps when changing gears 1998 malibu

My car has 243000 miles.
My car has an automatic transmission.

Mass Airflow Sensor Replacement $171.84 - $740.29 Get a Quote

Hi There, This may be related to a faulty throttle position sensor or potentially a dirty or failing mass air flow sensor. The mass air flow sensor monitors air intake as it is mixed with fuel prior to being injected into the motor. This sensor relays vital information to the ECM which uses this to make adjustments to fuel supply to the motor. A dirty or faulty sensor can cause an imbalanced air/fuel load to be supplied to the motor which results in an over fueling or under fueling situation depending on the conditions. This type of inconsistent fuel supply to the motor may cause a hesitation, loss of power, a jerking reaction, potentially a bit of black exhaust smoke and typically a strong smell of fuel when this sensor is malfunctioning. I would suggest having a professional from Your Mechanic come to your home to diagnose your mass air flow sensor.

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