Q: Why does my car jerk & accelerate by its self?

asked by on

My car recently started accelerating by itself when in parking gear. It doesn't do it so much in drive but when you completely turn off the ac it accelerates & de-accelerates. My car also jerks like little jerks & only sometimes, like when at stop signs.

My car has 160000 miles.
My car has an automatic transmission.

From what you’ve described, the jerking is most likely due to a misfire or a vacuum leak on the engine. You should have all the spark plugs and wires checked for misfiring after your computer is scanned for a misfire code.

You may have a leaking valve cover getting oil on the plugs and wires. Another possibility is that the engine may have a vacuum leak, causing the high idle and even the misfire if no other problems are found. A proper diagnostic should be done if any engine codes are present.

If you need help with getting this fixed, consider YourMechanic, as one of our mobile technicians can come to your home to diagnose the misfire firsthand for an accurate repair. Best of luck.

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. Why does my car jerk & accelerate by its self?

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: I have the regular dual clutch automatic in a 2016 Ford Focus 2.0 and my question is: Can I engage the "downhill" button while accelerating?

Hi there. You can push the downhill button, but not when accelerating. This will not damage the transmission, but it may damage the brake system. The downhill button function works with your vehicle’s existing braking systems to block you from...

Q: Is it my thermostat in my car that is not working?

You are correct, you probably do have an issue with the thermostat. When your thermostat is stuck in the closed position it doesn't allow coolant to run through the engine which is why you have the cooling effect. It will...

Q: Two mechanics have not been able to repair misfire.

Hi there. Check the intake for a possible vacuum leak around the cylinder 4. If there is no vacuum leak around the cylinder number 4, then there could be a burned valve. Check the compression on all of the cylinders...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.