For 15months, I have been experiencing acceleration problems with my 2004 Jeep 6 cyl. Grand Cherokee. The tachometer jumps at 2 and the car bucks when I am acelerating gently at 52, 63, and 68 mph. (Doesn’t happen during hard accelerations) My dealership has not a clue. They have rebuilt the trans, replaced the crank shaft sensor, and generally have been no help. I have suggestions from others that it could be the spark pugs, the cap and wires, fuel injectors, or the head gasket. I am out of $$ and worried about being stuck in a remote location. When I shared woes with my students, they unanimously told me to come to car talk. So here I am…ALL ADVICE IS WELCOME!.
You’ve been going back to a dealership for 15 months? Still under warranty?
You may have a vacuum fault, perhaps a crack in a vacuum hose or maybe a loose air intake component.
You could also check the Manifold Absolute Pressure (MAP) sensor (this controls fuel delivery and ignition timing).
Check the Mass Air Flow (MAF) sensor as well as this one controls air flow.
… so why was the tranny rebuilt?
what are the codes ? (this is pre obd2)
you need a good mechanic to check every thing, the evap sys. and vaccum, fule pressure, etc.
… has this been fully tuned up?
… is it worth fixing ?
… allpar.com has a site jeeps
Thanks for the advice. You guessed it there’s 20,000miles left on my warranty. I’ll suggest both these items next time I visit. Another post suggested a second opinion. I guess that’s overdue. Thanks again!
The tranny was rebuilt as the first response to the issue.The only code like info I have been given is after one particularly bad drive home, the mechanic said the oxygen sensor tripped. The dealership said that the O2 sensor was fine when they checked. I think that you are right. It’s time for a second opinion.
Thanks for all your help.
I had bucking symptoms from a much older jeep due to a throttle position sensor, but I believe it showed up in the codes.