Q: Engine accelerating on its own.

asked by on

5.7 liter 97 sierra. Accelerating on its own. Maintains speed at around 62 kmh.wont rev down when breaking at stops. Maintains an RPM around 12-1300 No cruise control. Changed IAC Valve and TPS valve.responds a little better, but still does same thing.

My car has 182000 miles.

In order for your engine to run this high, it has to have a stuck open throttle plate or a major vacuum leak. If you cannot find a vacuum leak, then try to pinch of the hose to the brake booster to see if it idles down. If it does then you may have a leaking brake booster diaphragm and need to replace the booster. If you have the hydraulic style brakes then you may have a problem with the intake leaking vacuum or the injection system leaking fuel from the regulator. You did not mention any computer service codes or fuel smells - these may help point towards a diagnosis. If you still need help a professional technician, such as one from YourMechanic, can come to your car’s location to inspect the acceleration issue and perform a repair.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Engine accelerating on its own.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: my truck has a whine on acceleration around 1700 rpm, what is it?

The noise is most likely coming from a bearing in the transmission. The noise is created when you put pressure on it under acceleration. I would need to hear the noise to be sure but this is common on this...

Q: Ignition makes clicking sound

This can be caused by either a low battery charge level, or a loose connection in the starter circuit. The battery needs to be fully-charged, and load-tested, to ensure it is not the issue. All starter wires need to be...

Q: Car troubles with 97 lincoln continental

Hi Dawnmonique. Thanks for contacting us today. There are several possibilities that are causing this hard to start issue based on your input. It's quite possible that the excessive power steering fluid on the crankshaft position sensor is causing this...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...