Q: Car suddenly stops accelerating.

asked by on December 03, 2016

When accelerating, sometimes my car will stop and continue going at around 40 mph. No matter how much I press the gas it wont accelerate. Just stay going 40 mph. It's as of it gets stuck in the 2nd gear or something. This is scary when going down the highway. After letting off the gas and slowly accelerating again several time it will grab and start going again. What's causing it to stop accelerating or maybe causing the 2nd gear to get stuck?

My car has 88000 miles.
My car has an automatic transmission.

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 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 bit 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.

The throttle position sensor (TPS) is a sensor used to monitor the throttle position of the throttle plate inside the throttle body in relation to your foot position on the gas pedal. Based upon the inputs from the sensor reading your foot’s position on the pedal, the ECU then makes the direction to supply more or less fuel to the motor. When this sensor is not working properly, this can cause intermittent responses when pressing the gas pedal as you have experienced. I would suggest having a professional from YourMechanic come to your home to diagnose your vehicle’s running condition.

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