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Q: RPMs go up and down

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Usually, after driving for about an hour, the RPMs go from around 2, jump up to 3, then back down again, accompanied by a jolt. This happens until the car is turned off and rested for about 30 minutes. I have also had it happen without driving for a long time.

A: Hello. Your car is equipped with a computer...

Hello. Your car is equipped with a computer-controlled transmission, so a scanner should be connected, the system checked for codes, and the data analyzed. This vehicle doesn’t have a dipstick for the transmission, so a special procedure must be followed to verify the trans level. You didn’t mention at what speed or in which gears this occurs, but a 1000 rpm difference sounds like it’s jumping between gears (i.e., gear 3, to 2, back to 3). You may need the aid of a mechanic to check the trans level and connect a scanner, and consult your last road test for a proper diagnosis.

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