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Q: High RPM's when pressing brake

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I just bought a 2004 Nissan Maxima and im having problems with the rpm's running high. When I hit the brake the rpm's go up a few hundred and then will come back down and when this happens I can feel the jump in acceleration. Also BC the rpm's run high, when u go to shift into another gear without letting the rpm's come down, it will shift hard making it feel like my transmission is hitting hard. Anyone know what could b causing this???

My car has 162000 miles.
My car has an automatic transmission.

Hi There, There are 3 sources of signals that are involved in up and down shifting points the computer arrives at to direct transmission shifting.

  1. The Idle Air Control Valve. The idle air control valve is a small valve on the engine’s intake system that reads the air intake as it comes into the motor. This is controlled by the car’s ECM which uses this information to make adjustments to the air/fuel ratio depending on various inputs such as outside air temperature, intake air temperature, load and various other things. As you accelerate, your car’s engine is receiving a much higher dose of fuel than when at idle and conversely, when you let off the gas pedal, there is a sudden change in this fuel supply as a result of your foot letting off the pedal.

  2. The Throttle Position Sensor. The throttle position sensor monitors 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.

  3. VSS speed sensing. The transmission speed sensor is a magnetic sensor that provides this information, allowing the transmission to shift smoothly. The sensor counts the internal number of revolutions of the transmission and transmits that information to the transmission control unit, where the data is used to determine the rotational speed. As the rotation increases, the control unit directs the changing of gears. When this is not working properly, this may cause the transmission to shift erratically or in some cases not at all.

I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your vehicle to determine what may be causing this.

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