94XjSport94

Today i left school around 2 and i drove home and then around town some. On the way to my grandparents i felt a slight stutter almost in the jeep. I thought at first it was my tranny but i watched the tach and when i felp the stutter or burp almost the tach would drop down and kick back up. Idle is fine on the jeep no problems what so ever. When i accelerate everything appears to be well, except that the shift points are extremely high like upper 3k and i never get it that high. The more i drove around the worse this problem got. The Check engine light came on and I drove to several garages in town and of course they either didnt have a OBD1 scanner or i would have had to wait for a few hours. Of course the dealership wants 90 to scan it but pay for their over priced labor and parts and the scan is waived. The Light doesnt come back on start it waits until i start driving so the computer should still store it but i cant get the code because it goes away. The weirdest thing is that tonight i drove home from church and nothing happened like that at all everything appeared to be like normal. All my plugs wires cap and rotor are all new (2 Months), so i dont think it would be something like that but if it was wouldnt it be happening all the time not just acceleration but idle too? Same with anything fuel line related or pump, like it would happen all the time not just acceleration right? Im thinking its time for a new o2 sensor anyway cause ive got 166k on my 94 and im pretty sure the sensor has never been changed so im planning on doing that but what would have caused this to happen just this one time? thanks guys!

Programbo

You can use the turn the key on-off-on-off-on method and get the codes from the computer even if the check engine light goes out they are still stored unless you disconnect the battery.

94XjSport94

Ok ive done it before when the light stayed on but i didnt know if you could with the light going of with the car

94XjSport94

I got a code 12 which the Chilton book says it: Memory to controller has been cleared within 50-100 engine starts. Dont really get this cause it happened like 5 starts ago so whats next?

Programbo

Burn it it's a witch! Just teasing. Guess as soon as the check engine light comes on try again.

Slick761

Is the cel still on? No doubt its being caused by a sensor.. under throttle probably map or o2

wiggles

I have a problem almost exactly the same as yours but no check engine and no codes, I replaced the o2 and it didn't effect it on mine ( not saying you shouldn't since your overdue) over time and with a large amount of research and I think I have narrowed it down to the fuel pump which I plan to order a new one within the next 24 hours

94XjSport94

Tried it again today and got code 13: MAP sensor pneumatic signal-no variation in MAP sensor signal is detected or no difference is recognized between the engine and MAP reading and the storage barometric pressure reading. Also got code 24: Throttle Position sensor voltage high or low. So replace both is there something else to do? Another thing that is strange is that this only seems to happen in the afternoon cause this morning on the way to school it was fine and tonight after work it was fine but after school for 2 days this has happened.

XJ-nick

It's probably just tired of you going to school and leaving it sitting all day in a parking lot instead of on some rock trails!

94XjSport94

Haha i bet! This GA sun is beating down on him all day but i did hit up some trails earlier this week when we got a little rain so itll buff out. I like going to school and seeing every ones lifted Jeeps and trucks that mommy and daddy buy for them and then seeing my great 2WD XJ covered in mud next to there brand new JK's perfect example of Built Not Bought

VTJeep

Same issue. Hesitates, idles rough and pops (backfires) from manifold. I've replaced everything, flushed gas lines, ran sea foam, you name it... And so far as we can tell, it's in the wiring. Here's the weird part; this issue happens EVERY time I start it. But I've found a weird way to make it stop: go WOT thru like first gear and the issues gone... Idk...

94XjSport94

So you havent replaced any of the sensors or wiring to them? For the MAP and TPS sensors its around 80 bucks which i dont mind paying if its going to fix it lol and i have a free $20 to Autozone

Slick761

........ I hate to say it but there may be a burnt exhaust valve in play. It happens a bit more then people think due to the exhaust manifold being so prone to cracking. Hook up a vacuum guage and see what it does at idle. It should be steady. When you rev it it should drop then hold steady. When you drop off throttle it should go up then settle back. I have a burnt valve. I have a slight miss and my vacuum at idle sits around 16 at input to the egr solenoid but it dips to 15. When revved it holds steady.... this tells me I have some kind of sealing issues in a chamber. Hoping its a spark plug, betting on a burnt valve.... also could be carbon build up..... out comes the seafoam for me..... not holding my breath.

GreenXJ95

Sorry to hear keep us posted

Slick761

Chances are for me I will run it for a while till I can afford a port kit plus all gasket and valves plus machine work. If it is a burnt valve in mine it is still sealing just not great. I'm gonna seafoam it and run a compression test tomorrow.