My XJ runs rough - looking for ideas

[wolfheartak]

Hey guys, looking for ideas. A few days ago I get in the jeep to go on a run and it runs like crap. When I try to accelerate, it will drop a few 100 rpm, and then jump a few. After a couple rounds of that, it would finally change gears, but it would still feel under power. Cruising down the highway, every few minutes it will vibrate and shudder a little, then go back to normal.

Check engine light came on, took it to the shop, they fixed a few things, reset and came on again (which is what we wanted to happen at the time). Fixed a few more things, and the light stays off, but not everything is back to normal.

Anyway, There is a TSB for this (I don't know the number) and it says to run the carbon cleaner through that you leave overnight. Then if that doesn't work, you have to take the head off and basically manually clean that valves.

After replacing a the rear O2 (which I had problems with before), and throttle position sensor, spark plugs, running that cleaner, it runs much better, but not 100%. Is taking the engine apart my last option? The local shop here is good, respected in the 4x4 community here, and I trust them - But I mentioned asking around people in the know of XJ's and they told me to see what you all have to say. Anyone else have the same thing? Anything we should try or something you guys know about that has worked? It's an 00, A/T, 4.0, 4x4

Thanks!

-Marisha

(Sorry, it's long and I know this should really go into the Tech forum, but I'd rather just ask you guys.)

[GSequoia]

Well I haven't experianced this particular issue but if the problem is buildup at the valves I'd run some Sea Foam through the intake to see if that helps.

Just buy a can, pull off your brake booster vacuum line and slowly pour it in. It helps to have somebody there to push the throttle down (it'll want to stall...badly; if you don't have anybody to help you just pull on the throttle linkage at the throttle body).

I pour it in as quickly as I can while keeping the engine running. Get a second can and toss it in the gas tank (while full) to allow it to work through the injectors as well.

Be warned - this will create a LOT of smoke. It will also make the Jeep run like dog shit for the next few miles generally.

Just did this in the Neon - actually the symptoms were somewhat similiar to yours now that I think of it... Cleared up it up well.

[Gerr]

sea foam is what id try as well

[sintax]

My guess would be that your jeep is just sick of being in AK for so long. I bet it would clear up if you moved back down here. =)

My 99 was doing the same thing, it ended up being a vac leak post TB.

[tcm glx]

Hey guys, looking for ideas. A few days ago I get in the jeep to go on a run and it runs like crap. When I try to accelerate, it will drop a few 100 rpm, and then jump a few. After a couple rounds of that, it would finally change gears, but it would still feel under power. Cruising down the highway, every few minutes it will vibrate and shudder a little, then go back to normal.

Check engine light came on, took it to the shop, they fixed a few things, reset and came on again (which is what we wanted to happen at the time). Fixed a few more things, and the light stays off, but not everything is back to normal.

Anyway, There is a TSB for this (I don't know the number) and it says to run the carbon cleaner through that you leave overnight. Then if that doesn't work, you have to take the head off and basically manually clean that valves.

After replacing a the rear O2 (which I had problems with before), and throttle position sensor, spark plugs, running that cleaner, it runs much better, but not 100%. Is taking the engine apart my last option? The local shop here is good, respected in the 4x4 community here, and I trust them - But I mentioned asking around people in the know of XJ's and they told me to see what you all have to say. Anyone else have the same thing? Anything we should try or something you guys know about that has worked? It's an 00, A/T, 4.0, 4x4

Thanks!

-Marisha

Hey Marisha, check the throttel position sensor...runs around $40. But that usually causes a stutter, as well as poor shifting and loss of power. It is located on the throttle body, and is very easy to replace.
(Sorry, it's long and I know this should really go into the Tech forum, but I'd rather just ask you guys.)

[djblade311]

I'd recommend thoroughly cleaning the Throttle body, Idle Air Control motor, Throttle Position Sensor (not the sensor itself but around it), etc.

After doing the Sea Foam as mentioned previously, you might need to check your o2 sensors / Catalytic converter again since the fog can foul those out.

Should also check your fuel pressure at the rail. Perhaps your fuel filter is getting clogged and making your engine run lean.

[wolfheartak]

Thanks guys, I'll see if any of those work. Speak up if anyone else has any bright ideas!

Miss you all!

-Marisha

[karstic]

See the problem is that the permafrost has settled into your engine. The only thing that will solve it is warm, :sunshine: sunny days at Fiesta Island, rocky, dusty trails out in the desert and MAYBE, JUST MAYBE an occasional snow run up in the mountains.

[corbinafly]

You didn't say anything about the MAP sensor. Did you change that also? I don't think it's carbon buildup if it started suddenly one day. Carbon buildup usually happens gradually.

Kyung

[Kejtar]

Check engine light came on, took it to the shop, they fixed a few things, reset and came on again (which is what we wanted to happen at the time). Fixed a few more things, and the light stays off, but not everything is back to normal.
What codes did it throw originally? What was it that they fixed first???

After replacing a the rear O2 (which I had problems with before), and throttle position sensor, spark plugs, running that cleaner, it runs much better, but not 100%. Is taking the engine apart my last option?
What you're describing reminds me of a bad TPS I had. The first one I put in was not a dealer item and it failed me soon after. Once I got an OEM TPS my problems went away. Funny thing was that when the first TPS started failing it threw the code twice and then it stopped. When the aftermarket one started failing it did not throw any codes at all.

[wolfheartak]

The original codes were tons of misfires and my O2. Fixed the O2, replaced the spark plugs because they were all nasty. Then trip #2 was more misfires and the TPS. Nothing since.

I've put a can of carbon cleaner through it, and it's tons better. I think I'll try one more and see if that does it. The TSB for this just basically says my engine is dirty. Hate it when that happens. (And Sintax an Karstic, yes it's worse when it's cold - thought you guys would get a kick out of that, maybe you're a little right)

I'm not 100% that it happend all of a sudden, I just noticed it all of a sudden. I drive my jeep maybe twice a month. It's always run kinda rough, and would misfire from time to time. But that would always happen when I was wheeling, it was just one of those things. Didn't do anything with the map sensor. No code, it should still work fine.

Drove it this wheeling this weekend, and it did good most of the time.

-Marisha

[90xj06]

where do you get this seafoam stuff??? and whats the name on the bottle???

[corbinafly]

where do you get this seafoam stuff??? and whats the name on the bottle???
White metal can with red writing that says Sea Foam. You can get it at napa. Autozone out here also carries it.

Kyung

[90xj06]

so at napa. allrighty. you can put this in gas and oil correct. and will there be like a plume of smoke? it sounds like there always is.

[corbinafly]

so at napa. allrighty. you can put this in gas and oil correct. and will there be like a plume of smoke? it sounds like there always is.
You'll get a LOT of smoke if you put it directly into the intake thru the brake booster hose. Just follow easy directions on can.

Kyung

[Kejtar]

I'm not 100% that it happend all of a sudden, I just noticed it all of a sudden. I drive my jeep maybe twice a month. It's always run kinda rough, and would misfire from time to time.
You might want to take it for a spin regularly once a week. I have found that my jeep "misbehaves" if I leave it sitting for too long. Also it doesn't have to be a long trip, just something so that it can stretch its legs.

[GSequoia]

I have found that my jeep "misbehaves" if I leave it sitting for too long.

Me too!

:laugh3:

[wolfheartak]

My jeep throws temper tantrums like a 5 year old in the candy aisle.

-Marisha

[goodburbon]

When you replaced the spark plugs, you went with the oem plugs right?

As an aside to that, I picked up some plugs at the stealership about a month ago and they gave me NGKs, not the Champions I was expecting.

[GermanXJ]

Vac leak