Phil_XJ

I've been reading a lot on this issue and it appears that the most common culprit is the CPS. I just want opinions on here before I pull the trigger because I am not so sure.

I have a 1993 Jeep Cherokee 2.5L standard transmission

These past couple months, the jeep has been acting a little weird on the freeway at random times - it would sort of jerk or sputter a bit but be fine a few seconds later. I replaced the spark plugs, plug wires, and it seemed to be fine for awhile. Then it came back. It has also stalled out on me a few times when i'm coming to a stop. At first I thought I was just an idiot and didn't punch the clutch in time. Then this past Friday it was constantly stalling on me. Almost every time I'd hit a stoplight or stop sign or slow down it would sputter and die. Flooring the gas when it was acting up did not seem to matter, but sometimes the RPMs would go right back up at the last second and save itself from dying. If it did die, it would always fire right back up and I'd just keep going. None of the gauges were freaking out or anything, they all work perfectly fine during these episodes. It's very random though. The sputtering at speed got worse and more frequent, but still random, to where I had to turn around and park it for the weekend.

Go back on Monday and it's been working fine ever since, I tried to reproduce the problem by letting it sit at idle until hot and it never died or sputtered. I have not tried it on the freeway or for extended drives because I'm worried about it. I thought maybe it was grounding out intermittantly somewhere but I tested the battery, alternator, and fuses and all seemed fine. CPS seems to be what everyone thinks causes the stalling issue, and I've also heard that the O2 sensor does. I checked my engine codes and I have no codes at all other than the standard 55 and 12 (from messing with my battery). It also was doing this with or without the a/c on, so I know it's not related to that. Any other possibilities?

ZINGGG

Get your battery load tested to make sure it is up to par. After ruling that out, replace your CPS. That sounds like it is what is going on most definitely.

Phil_XJ

Even though there is no engine code?

ZINGGG

Yes, it wouldn't necessarily automatically throw a code.

It's kinda like how o2 sensors can get "sluggish" or "lazy", causing a decrease in mileage and rough idle. But the ECU wouldn't necessarily recognize it as faulty and throw a code.

Phil_XJ

Ordered part from dealer, came out to $97.97, and I plan on fixing it this morning. I'll let you know how it goes, thanks for your input.

VTJeep

I think generally when the CPS goes it just goes. But I could be wrong so it's worth looking into. This also sounds like a potential o2 issue and/or o2 grounding issue. Or possibly a fuel delivery issue.. Does it ever backfire from the manifold?

VTJeep

Kinda sounds like the fuel Delivery might be getting compromised by a faulty signal from a sensor. What condition is TPS and IAC valve in? What about the rest of your stuff? Well maintained, tuned and grounded?

Phil_XJ

Well new sensor is in, the old one looks brand new though.. maybe the guy before me put in an aftermarket one which I've read are notorious for quick failures. It does seem to idle smoother, as in less shaking and jerking. Not that it was that bad before. Maybe it's just in my head.

Drove it about 5 miles on the freeway and a few miles city driving and no incident other than running a little hot on the freeway, which I was already aware of. Other than that, seemed to have the issue solved. I'll drive it around some more this afternoon to greater distance to see how it holds up.

Phil_XJ

Alright so the problem isn't entirely gone after replacing the CPS with a factory mopar one. I drove it 17 miles to a friends a parked it for about a half hour, then drove back those 17 miles. It didn't shut off on me at all, so that was good. About halfway back home it started doing the jerking thing again while driving. Pretty noticeably. It does feel like a fuel delivery issue. It was running slightly hot, around 215 or 220 most of the way due to another issue I think. Would that maybe cause these symptoms? I think I'll probably turn towards the O2 sensor next and clean out the IAC this weekend.

VTJeep

Is it backfiring at manifold?
Have you put it on a diagnostic computer?
Overall condition of ignition sys?
BOTH o2's?
Load test bat/alt?

And as for the running hot effecting it. It's possible if the under good temps are enough to cause the fuel to get to hot. When fuel is to hot it doesn't like to combust.
Get your rad. flushed too! Gotta eliminate things as you go to pinpoint! ( I'm ***uming thats why it's overheating?)

Phil_XJ

Overheat only happens at higher speeds, I could idle all day long. I would flush the rad. except in my experience with other cars it's almost pointless because you'll never get all the crap in there out. I'll just replace the thing eventually.

No backfiring at manifold.
Load tested battery and alt and were good.
I'll do some testing on the ignition system but I believe it's all in good working order.