Jeep Grand Cherokee Problem Report
Jeep Grand Cherokee Misfire due to carbon build up on exhaust valves
4.0L 6 Cylinder
Due to misfires, you may experience a loss of power when accelerating between 50 and 70 MPH (most noticeable below 32° F). This is commonly caused by carbon buildup on the valve stems, as a result the exhaust valves may close too late. All of the exhaust valves should be inspected and if necessary the engine should be decarbonized.
engine misfires in cold temperatures when heavy load is put on engine at highway speeds, also changed plugs and coil pack, did not help. still looking for help - Visitor
every once in a while, ill be traveling at highway speeds and my jeep just "jerks" kind of like shifting it from drive to N and back to drive really fast. i put some marvel mystery oil in the oil and gas and it has made it better but it still happens every once in a while. - Visitor
The temp was about 41 degrees and I was hawling my boat back home and the engine light kept coming on and the car was jerking. - Fran Achille
Engine light came on and took to shop said code for oxygen sensors replaced didn't make any difference returned (same code)then they said it was a false code that I had a burnt wire replaced wire ...
Have been fighting this issue since last Sept. Have had Cat converter heat test, exhaust system...
Usually it will shake when I first back up, but it will stop once I accelerate and start drivin...