Skip the auto shop - Our mechanics make house calls

Q: My car is jerking back and forth at high speeds

asked by on

Hi, I recently bought a car from a private seller and the check engine light has been on. When I go on the highway and speed up the car jerks back and forth. It does it almost every time I speed up but after I travel about 20 miles or maybe a little bit more it doesn't do it. What could possibly be wrong with it? Will it cost me a lot of money?

My car has 110800 miles.
My car has an automatic transmission.

A: The first thing that needs to be done is to...

The first thing that needs to be done is to connect a scanner to the car and retrieve the code. This information will lead a technician down a diagnostic path. There is an important distinction that needs to be made here. Does your car "jerk back and forth" while accelerating or at a cruise when the throttle and speed are held steady? These are different circumstances in regards to what could be wrong.

Surging at a cruise is usually a sign of a lean running condition caused by fuel system components. This could be the MAF, an injector, fuel pressure regulator, or fuel pump. Bucking and jerking while accelerating is usually do to ignition components. If there is a vacuum leak or the fuel pump can't supply enough fuel, you can get similar symptoms. The problem could be a mixture of several of these.

As for why it doesn't happen after twenty miles, this could be because a motor needs more fuel to run when it is cold. If the fuel system is performing as it should, this could easily be the cause. Several components have warm up cycles that may not be working correctly. If they warm up to slowly, numerous drivability issues can arise.

I recommend having your Check Engine Light diagnosed by a qualified technician, like one from YourMechanic, to help you figure this out.

Good luck!

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Blown engine

Check you dipstick to make sure that the proper amount of oil was installed. It's possible that someone forgot to re-fill the engine oil. It could also just be a coincidence that the Check Engine Light came on after the...

Q: Car jerking and surging as it accelerates

Hi there. This problem can be caused by a few things. First, your vehicle may be having trouble getting fuel to your engine. This would mean that there is an obstruction in your fuel lines or your fuel filter. Next,...

Q: A/C blows only warm air on driver's side; passenger side is cold

Some A/C systems have problems disconnecting or losing communication between the A/C control head and the temperature blend door actuators. This may require the A/C control head to be reprogrammed by a factory level scanner capable of the reprogramming of...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.