I've searched the forums and haven't found a post with my exact problems yet, so I'd try a post. I'm still a newbie with the mechanics, but I'm more than willing to work on w/e!
My Jeep has problems with stuttering and sputtering while driving, but unfortunately I cannot replicate the exact conditions that make it stutter, except that it is usually when I'm heavy on the accelerator like going up a hill.
When the car stutters it feels like I've run out of gas, and lose a lot of power in the car. I can shift into a lower gear and try to power through it but sometimes it continues to stutter in the lower gear as well, but usually goes away after a short amount of time It can happen on both side streets and freeways, regardless of current speed and rpms.
Sometimes, when the sputtering is very severe I can hear and feel some kind of thumping inside of the engine compartment. It sounds most like I am driving over a very uneven piece of freeway, with bumps.
I have changed the fuel cap, and fuel filter, put fuel cleaner/additive in the tank, and checked all the fittings in the engine compartment to make sure they are tight... but now I don't know what to do!
Mine was doing the same. I read on here where it could be the pickup coil in the distributor. Was going to just change that but after pulling the distriburtor I found for $20 more I could get a rebuild distributror with the pickup coil in it. After replacing distributor, all problems solved.
I recently bought this jeep (about two months ago) and the previous owner had only used it as a "dog car" for carting his dogs around town, and never taken it off road (what a shame). But about 2k miles ago had it tuned up with new cables, spark plugs and a few other things.
Since I've had the Jeep I've done the Mojave trail, and it ran beautiful from that. But after the trail, its been giving me all sorts of problems on normal roads! Very frustrating.
I will do a once over of everything and see what I can find out... The oxygen sensor sounds like a good start.
What do you guys think about a failing TPS? Could that be intermittent enough to cause issues like this?
Just to help muddy the waters, it could also be your fuel pump. My last fuel pump that went bad gave the same symptoms that you have now. My fuel pressure at the rail was a solid 39 (low but just barely out of tolerance). Under throttle it would spike as high as 41.
I could drive down the highway at 65 just fine for about 20 minutes, but after that it wouldn't maintain speed. If you want to see if this is your problem, wait until your Jeep starts bucking, pull over, shut of the engine, and then cycle the key a couple of times. If it runs fine for a couple of miles and then start acting up again when excess pressure that you created by cycling the key has had a chance to bleed off, I'd check the fuel pressure, but there is a good chance that your pump is just plain old worn out.
I LOVE jeeps! I never knew it was so easy to pull the codes... I put it off forever thinking I needed a code reader or something... Who woulda thought just turn it on and off 2x lol
Anyway, the codes I had were:
12, 21, 52, 55.
Which lead me to look into the O2 sensor like a few recommended, I swapped it out a few days ago and it seems to be running great now! Except that I have seemed to lost a lot of power... but I attribute that to the o2 sensor dumping tons of gas in all the time.
You need to clear the codes and reset the controller by disconnecting the battery for a long 10 count. and I would clean the throttlebody up. You shouldn't have a loss of power if it's running correctly.