The most frustrating issue... ever!

JMDesign83

JMDesign83

New member
Cherokee XJ 98'

Okay, so I've posted about this issue before, and I've read tons and tons of posts regarding similar symptoms... and replaced a ton of parts, but I haven't found it yet so I am in need of assistance.

This issue is this:
After about 3 or 4 mins of running (driving or sitting still), it begins to run rough like it's not getting air or fuel, or possibly a short of some kind. If I'm driving it, it will buck and hesitate. If I push on the gas when it's doing that it will kind of try to fight through whatever the issue is, but it's very rough and bogs down as soon as I let off the gas. If it's idling it will just run rough but never die. If I shut it off and turn it back on, it runs fine. Sometimes for the rest of the drive, sometimes only for a few seconds. The frustrating part is that though it happens most every time I drive it, sometimes I can get in and drive 50 miles without it happening. Though that is rare.

It seems to be an electrical issue because it's intermittent and runs perfect when it's not happening. And would appear to be heat related as it takes several minutes of running for it to happen. And, in theory, when I shut it off and turn it back on again it's giving whatever it is a chance to cool. But I could be completely wrong on that. Clearly, seeing as how I haven't figured it out yet lol

What I've replaced so far:
ECU
TPS
IDAC
CPS

What I've checked so far:
Fuses
Grounds
Connections
Air filter
Drained and refilled fuel tank

Things I haven't checked yet that I guess could be responsible:
Fuel pump
Fuel filter
Catalytic converter
O2 sensors
Battery
...fill in the blank here

Any thoughts would be very welcome. At the moment, I don't have insurance on it since it's sat for so long, and the inspection sticker is dead, so I really don't want to mess with going to AutoZone to have the codes read. But I will if it's going to be necessary.

Because 99% of the time it will start doing it If I just turn it on and let it idle for several minutes, it's fairly easy to check to see if I've fixed the issue with something I've tried. So I've wiggled cables, put dielectric grease on connections, etc. All to no avail. But any ideas you wise people have, I should be able to test out fairly quickly.

Im really just wanting to sell it at this point, but I'm wanting it running before I do. Which is why I've avoided replacing the cat, o2 sensors, fuel pump, etc. I doubt I'll get more than a couple grand for it, so if I replace all those things and it doesn't fix it, I'm basically just giving it away.

0a590164-606d-4840-bcce-6e09907f9413.jpg
20180605_141327.jpg
 
Oh, also, the issue began slowly and progressively got worse. It got bad enough (would be running rough as soon as I turned it on) that I actually took it to a shop where they said the ECU was fried. So they replaced it and it's back to being an intermittent issue. So it's possible that whatever it is fried the ECU. It could have just been a coincidence though.

However, when the issue first started, it would only do it once a week or even less. And all I'd have to do was shift to neutral, shut it off, start it back up, and carry on driving.

Sent from my SM-G935P using WAYALIFE mobile app
 
Last edited:
I had a similar issue one time on my race car. Turned out to be a fuel line. There was a piece of rubber inside and it would intermittently block the line a little and run like shit. Shut it off and re start ran fine. I can’t tell you how many things I tried and replaced before I found it. I was just cleaning out the fuel lines to check of one more possible and there it was. I couldn’t believe it. Replaced the line and never had the problem again.

I am not saying that’s what it is, but I bet it’s something stupid like that. I feel your frustration.


Sent from my iPhone using WAYALIFE mobile app
 
It always is lol If I hadn't already lost my patience with it I'd probably be tearing out fuel lines and ripping the dash apart looking for gremlins lol I'm just hoping someone wiser than myself on here has some ideas to point me in a constructive direction.

Sent from my SM-G935P using WAYALIFE mobile app
 
Had a similar issue and it turned out to be the fuel filter, but it was a carbureted vehicle. Characteristics the same as you describe though.
On the trail one of the ZJs had trouble and that turned out to be a shorting oil pressure sensor lead. One of the wires had insulation scraped off and it was intermittently shorting. Passenger side of the block. Electrical tape took care of that.


Sent from my iPhone using WAYALIFE mobile app
 
Thanks, I'll go ahead and swap the fuel filter to see if it helps. I'm leaning toward electrical because it's an intermittent issue, but I could see gunk collecting in the filter, then draining back with the fuel when it's shut off. I also just noticed the wires to my front o2 sensor look frayed so I need to get those wrapped up with tape.

Sent from my SM-G935P using WAYALIFE mobile app
 
I had a similar issue. Mine was the fuel pump acting up. Some times it would be just fine then all of a sudden not have any power and try to die. If I’d let it sit for a minute it would run fine again.


Sent from my iPhone using WAYALIFE mobile app
 
It sounds like a bad o2 sensor to me. When you first start your vehicle the computer has a set idle until the O2 sensors are heated up and online which usually takes a few minutes. Once they are heated and ready they tell the engine computer what your fuel/ air mix should be to keep your vehicle running smooth regardless of the outside temp or elevation you’re at. When an o2 sensor starts to go bad it will send faulty info to the computer and usually cause misfires and stumbling at idle.
If it were me I’d stop winging parts at it and get a scan tool (most of the cheap ones these can tell you what your o2 sensor health is). If it’s something else it will at least give you a direction to go in. Good luck and let us know how it goes


Sent from my iPhone using WAYALIFE mobile app
 
That makes sense, I appreciate the info! I'll get it scanned to see which sensor it is. The forward sensor does have a fray in the wire, and the wire is rusting, so I probably need to at least replace the lead. I just noticed it a bit ago when I was under there swapping out the CPS lol

Sent from my SM-G935P using WAYALIFE mobile app
 
A guy that used to work for me had a beef with a guy over a girl and he started having weird problems with rough idle and stalling out.... very similar - sometimes it’d be fine then appear and go away after off/on.

They ended up putting a scope down his gas tank and finding a crapload of rubber balls similar to the airsoft ammo. The way it was described is the fuel filter catches them and when there’s no more suction they go back to the bottom of the tank, or float, or whatever.. just out of the way of the fuel delivery.

That’s what he told me anyway


Sent from my iPhone using WAYALIFE mobile app
 
Well I doubt thats my specific issue, but same concept I was thinking earlier with gunk collecting at the filter and then draining back when the pressure is removed. But I think I'm leaning toward the o2 sensor. JuDesign's suggestion makes sense so I'll give it a go.

Sent from my SM-G935P using WAYALIFE mobile app
 
JMDesign83 said:
Well I doubt thats my specific issue, but same concept I was thinking earlier with gunk collecting at the filter and then draining back when the pressure is removed. But I think I'm leaning toward the o2 sensor. JuDesign's suggestion makes sense so I'll give it a go.

Sent from my SM-G935P using WAYALIFE mobile app
Click to expand...

Good luck. The phantom issues are the worst ones. Hopefully it’s something easy and cheap to fix
 
I forgot to update this thread. JuDesign was correct, it was the O2 sensor. Swapped it out and it runs fine 😊 Its infuriating that it was something that simple after replacing tons of parts. I think the sensor itself was fine because I checked it ages ago when it first started having symptoms. So I had written it off as the cause. The wire however, probably became more and more corroded, hense the progressively worsening symptoms over time. The fray in the wire was hidden just above the control arm so I hadn't seen it before.

Anyway, glad she's running. Thanks for the help!

Sent from my SM-G935P using WAYALIFE mobile app
 
You must log in or register to reply here.
Top Bottom