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Q: Engine light and rpm increased while driving

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When driving the engine light comes on. The rpm jumps 200 to 300 more and drops right after the car jerks and it feels like the engine is acelerating. This happens on and off. When stop at a light on drive car acelerates by itself. Black smoke and fuel smells. Already change trotle body sensor and fuel sensor. Have been check by 2 mechanics can find problem. Car shots off while driving one time

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

A: This is a common sign of a dirty or failing...

This is a common sign of a dirty or failing mass air flow sensor. The mass air flow sensor is a unit in the intake system that monitors air intake as it is mixed with fuel prior to being injected into the motor. When this is dirty or faulty, this causes 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 bot of black exhaust smoke and typically a strong smell of fuel when this sensor is malfunctioning. When this is not working properly, you may also notice a strong smell of fuel. I would suggest having a professional from Your Mechanic come to your home to diagnose your mass air flow sensor.

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