Q: Acceleration automatically.

asked by on March 17, 2017

Car check engine light is off. Car accelerates by itself in drive from 0 to 60 miles an hour. Replaced aci, no codes on computer, throttle is closed when car accelerates to this speed. When idle bypass valve is unplugged the automatic Accelaration stops we replaced it because valve was stuck and it didn't fix the problem. Please help. We're at a standstill and it is very dangerous. When brake is applied the engine revs hard. When driving it doesn't going nearly as fast but still moving soley on its own. Came to a hard stop. We took the tires off and have it on jacks this is where the speedometer goes wild in drive as well as the rpm. Usually about 3000rpm.

My car has 176000 miles.
My car has an automatic transmission.

Hi there. There is an issue with the engine having a vacuum leak and the may be cruise control is coming on to accelerate the engine. First check for any vacuum leaks on the engine. If the engine is running very fast with the throttle plate being shut, then there is an external air leak coming into the intake manifold. Then check the cruise control switch and make sure that it functions properly. A vacuum leak or a failed cruise control switch can cause the engine to race up and speed the vehicle to an astonishing speed of 60 mph. If you need further assistance with your engine speeding up, then seek out a professional, such as one from Your Mechanic, to help you.

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