Q: When I'm driving, sometimes the car over revs and jerks when I shift gears after the cars been on for a while

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After awhile of driving, the car sometimes revs high (like when you give the car gas when it's in neutral) I usually let go of the gas until it catches back (if you get what I'm saying) it usually happens around second gear at about 2500 to 3000 rpms. It starts to happen maybe about a half hr after I turn the car on driving around town (on the highway I'm fine) and when I shift gears from like Reverse to Drive it takes a couple of seconds and then the car jumps. Can you tell me what that is? (I'm thinking transmission but I'm no mechanic) Thanks

My car has 157000 miles.
My car has an automatic transmission.

Hi There, What you are describing may be a result of a faulty speed sensor, potentially low transmission fluid or a even a faulty transmission control solenoid. As your vehicle travels down the road, the computer analyzes data being sent by vehicle speed sensors and engine speed sensors. Based on this information, the Engine Control Unit (ECU), or the Transmission Control Unit (TCM), executes the appropriate upshifts and downshifts by sending a signal to one of several shift solenoids. These transmission solenoids have spring-loaded plungers inside them, which are wrapped with wire. When this coil of wire receives an electrical charge from the TCM / ECU, it causes these plungers to open, allowing transmission fluid to flow into the valve body and pressurize the desired clutches and bands. When this happens, the transmission changes gears and you continue down the road. The computer controls the transmission solenoid in several ways. If the vehicle is equipped with a dedicated Transmission Control Unit, it can open or close the hydraulic circuit using a direct 12v signal. In some cases, the Engine Control Unit (ECU) can control the solenoid’s plunger by turning the ground circuit on and off. I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your transmission.

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