Q: My car jerks slightly when I'm at a steady speed or trying to stay at a constant speed only around 40mph to 50 mph

asked by on

when I try to stay at 40 45 mph my car chugs jerks slightly, but when I hit the gas it goes away only usually at those speeds. I replaced spark plugs all but number 3 today didn't change anything, change tps nothin, changed air tempature sensor and no change. I am running out of ideas also when I hit the gas hard I get black smoke. Took it to auto zone to get a diagnosis and the Egr code came up as well as fuel system lean... please help

My car has 163000 miles.
My car has an automatic transmission.

In the future, please include the codes as they can help use pinpoint and give you a more accurate answer.

The surging you feel while under light throttle, which is what is happening at a cruise, is due to a lean condition. Just as your codes suggests. Since it also mentions your EGR, this is a good place to begin since EGR systems can develop restrictions that keep the valve stuck open. When this occurs, there is an internal vacuum leak created by the EGR valve. A vacuum leak is when there is air entering the motor from unwanted paths. When this occurs the fuel system will need to add more fuel to keep the air-fuel ratio in balance.

I would begin by inspection and cleaning our EGR passages. You may need a new EGR valve and other EGR components. But don’t change these components until they have been inspected and found to have problems.

Aside from the EGR system, the best way to inspect for a vacuum leak is with a smoke machine. The next best technique is to use an arosol spray such as brake cleaner. You will want to liberally and selectively spray it in suspected areas.

Another possibility is low fuel pressure.

I suggest having a certified technician, like one from YourMechanic, diagnose your car’s jerking symptom firsthand. They’ll be able to diagnose the trouble code further in order to pinpoint and fix the issue.

Good 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. My car jerks slightly when I'm at a steady speed or trying to stay at a constant speed only around 40mph to 50 mph

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: Q: My car won't shift gears

Hi there. When this transmission starts sticking in gear like this it is typically the first sign of an internal transmission failure. The solenoid pack should not have to be installed prior to checking the transmission pressures to see if...

Q: I have an 04 chrysler sebring with vin#g 2.4 liter and it shifts hard from 2nd to 3rd but doesnt shift into 4th

Hi Seth. Thanks for sending in your question tonight. In most cases, what you are describing is caused by either damaged internal transmission seals (causing an internal leak), dirty transmission fluid or an obstruction of debris inside the hydraulic lines....

Q: Q: Timing chain problem?

It could very well be a timing chain problem. The P0016 and 17 indicate that the camshaft sensors are sensing the camshaft in a position that does not logically correspond with the crankshaft. The P0302 and P0355 codes are misfire...

Related articles

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...
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...
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.