jeep is running weird 1998

Quote from Solomi

Ok, so over the past year this tiny little problem with my Jeep has progressively gotten worse. About a year ago I noticed that sometimes immediately after starting the Jeep up it would sputter - it would sound like it wasn't hitting on all 6. All I'd do is put in the clutch, wait a few seconds, then drive like nothing happened. As another example, last year while down at the beach, I'd fill up at the gas station, then while leaving and turning left onto Rt 1. to go back north, it started sputtering. It barely limped through the intersection. I kept my foot on the gas and after about 10 seconds everything was normal - it got all its power back. Last winter I noticed that it wouldn't idle right over the rocks in low range, the RPMs would get low and then the engine would kick it back up to ~1k. This made it difficult to control but simply turning off the heat fixed the problem. This most recent summer the same problem came back but didn't go away even with the heat and a/c off. This season I've already driven it down to the beach and driven on the sand without issues, except that when it sputtered after starting up it started to buck with a lot more force and lasted longer than before. I've replaced the TPS, removed the throttle body, IAC, and MAP sensor and sprayed it all down with sensor cleaner and re-installed: no difference. I am unsure of where to start trouble shooting and what good a shop will do in diagnosing it. Any help is appreciated.

Thanks a lot for reading,

Sal

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[size=3]Sal, [/size]
[size=3]I check this site regularly and this was the first time I saw this post, this is very similar to the issue’s I have been having with my jeep. My research has led me to several causes:[/size]
[size=3]Vaccum leak[/size]
[size=3]Bad Crank Position Censor[/size]
[size=3]Bad Throttle Position Censor[/size]
[size=3]Bad Cam Position Censor[/size]
[size=3]Bad Oxygen Censors[/size]
[size=3]Clogged fuel filters[/size]
[size=3]Bad fuel pump[/size]
[size=3]Clogged or fouled injectors[/size]
[size=3] [/size]
[size=3]I have replaced all of these to attempt to fix the issue, but I believe the problems on my jeep were a vacuum leak, with a bad downstream O2, and CPS. I have a Snap-On diagnostic tool that I used to figure out my injectors were fouling, then a fuel pressure tester to find out the fuel filter in the fuel pressure regulator was clogged, and then replaced the O-2 and CPS. The problem is now infrequent, only happening every now and then, but still occurs. [/size]
[size=3] [/size]
[size=3]As far as the sluggishness mine was caused by the distributer being slightly off, It felt like the timing was off, the motor hesitates and when you push the gas feels like its drowning. The biggest fix for me was to adjust the distributer to bring it back into the sweet spot. This might not be an issue for you but since my jeep has been put together like Frankenstein this was one of my issues. So check to make sure your distributer it is secure. [/size]
[size=3] [/size]
[size=3]Other than that they only code the jeep throws is a high TPS voltage, which I think Is cause by a ground issue from the rewire or maybe the fact that I have no evap loop. [/size]
[size=3] [/size]
[size=3]Either way ill plug in the computer tomorrow and see if I can video the hesitation. [/size]

Cj-

I pulled the head on my 98 TJ engine last night and pulled the valves. What i found the problem to be was carbon build up on the stem which was getting pulled into valve guide making the valve 'tight', couple that with weak original valve springs and i got an intermitant no power, sluggish sputtering until the valve or valves free'd up. I'm not suggesting someone go as drastic as i went since i was planning a complete rebuild anyhow, but i would suggest running a couple cans of mopar upper engine cleaner through it, as one of the bad side effects i got was wear to the valve stem and guide which is making me have to regrind all the valve seats, ream the guide, and use oversized valves. That ounce of prevention thing you know

Quote from Erock

is that the stuff that you connect directly to the schrader valve on the fuel rail and disconnect the fuel pump and run the engine for a bit?

No, this comes in an aerosol can that you spray into the intake while revving the engine, then stall the engine while still spraying it nd let it sit for a couple hours. For badly carboned engines it can take multiple applications.

However the stuff you hook to the fuel rail can do a similar job, if you could do the spray can followed by the fuel rail treatment it would be optimal.

Quote from Karvor

No, this comes in an aerosol can that you spray into the intake while revving the engine, then stall the engine while still spraying it nd let it sit for a couple hours. For badly carboned engines it can take multiple applications.

However the stuff you hook to the fuel rail can do a similar job, if you could do the spray can followed by the fuel rail treatment it would be optimal.

If you do any of this (seafoam) works great too, change the oil when you are done! That's where a lot of that crap ends up. Not all out the exhaust.

I'm not familiar with that kit, but if it works like i think it should just remember that you will be 'fogging for mosquitoes' so might wanna do it when there are no neighbors around to complain . Let us know if it makes any difference for you.

When my Wrangler TJ was acting like that it was the Crank Position Sensor. Another time it was the main ground cable was loose on the side of the engine block. I wish you luck. These situations can be maddening.
Marko