Tjlance1

I have - 97 GC - 4.0L - 125,000M.

Was having stalling issues. Would start fine, then about 5 minutes into driving would lose power and or would stall. After initial attemots to re-start, would smell fuel in the cabin. Once the GC started it would be fine for rest of day. Stalling issues were getting worse, then waterpump went this past Friday.

New waterpump and thermostat installed. Also, coil pack replaced. Service station I brought it to said that was causing the stalling.

No more check engine light, but still stalls very internittently tho, but now after driving about 20 minutes or so, the engines bogs down like it's flooding and I have massive bucking and the some huge backfires.

After that, it runs fine.

Any thoughts?

Bustedback

Could be anything, TPS, cam sensor, fuel pump, clogged fuel filer, crank sensor, anything. This going to sound expensive, but I would have a Jeep dealer or a shop that specializes in Jeeps take a look at it. It will cost you less than throwing parts at it and guessing.

Nitrospaz9

I was having a bad bucking on my 97 to. Mine was an upstream o2 sensor. Try disconnecting it for a day or two. Ur check engine line will come on. It's not hazardous to the truck so give it a shot. If it is the o2, it's like $70. Can't beat that.

Bustedback

Running without the up stream O2 can cause an overly rich condition and will ruin the catalytic converter if run too rich for too long.

Nitrospaz9

Yea it can. That's why I said for a day or two. I had mine off for about a week. As long as your not driving a lot it will be ok for a bit. I only do like 10 miles round trip to work.

gmv93

but i will consume horrible amounts of gasoline.

Nitrospaz9

The gas milage doesn't decrease that much and like I said only do it for a day or two at the most.

Tjlance1

Update from the original post.

The stalling and backfiring issues got worse. The backfiring got so bad that the muffler blew apart. Service station diagnosed it as bad MAP sensor. They replaced the MAP sensor, new muffler and section of exhaust pipe. Ran great for two days and stalling issue came back, check engine light came back on. It wasn't as bad so I basically ignored it. (Lack of money will do that.) I ran it another three weeks until the backfiring began again, along with worsening of the stalling.

Toook it back to the service station, they traced the problem to a short in one of the wires coming from the PCM. They bypassed it and it seemed fine. Picked it up and two days later it started all over again. By accident, I discovered that putting it in 4WD caused an improvement. Still stalled, but not on the highway and not nearly as frequently. I drove it like that again for a few weeks. Brought it back to service station last week, they kept it for a full week. Called me and told me they had no idea what was wrong with it and that they coulod not fix it. They referred me to an auto electric station. They told me flat out no way they would try and tackle the problem. They referred me to another service station. Was supposed to drop it off this evening, but it got so bad on Saturday, even in 4WD, I decided to check the boards and do a google search. Lo and behold, several people have had same issue. I checked the PCM connections, all good, so did the next suggestion, backed the screws out fron the PCM cover about 1/4 inch.

She now runs perfectly! I have a part time job that is an hour from my home and it has been a nightmare trying to get there most days. Today, it was the best drive I have had in weeks! LOL... I plan on going back to the service station I normally go to, to let them know about this fix. It's simple and effective. I know it doesn't work 100% of the time, but it's definitely an inexpensive starting point, before going sensor replacement happy.

Tjlance1

On 11/13 I posted how turning the pcm cover srews out about 1/4 inch made my 97 GC run 100% better after having three mechanics try and fix it. It made it until mid-January when the problems started to occur again. Stalling, backfiring, bucking. Took it to another mechanic on a recommendation. He was upfront and told me he would need it for about a week in order to properly diagnose the issue. He was almost ready to change the crank shaft sensor, but wasn't convinced that was the problem.

Come to find out, when he cross referenced the vin# of my Jeep, he was able to figure out the pcm for my jeep was supposed to be for california emissions but the one actually in my jeep was for federal emissions. He made some phone calls, got a hold of the right pcm and bam, its been fine ever since..Seems the pcm might have been swapped out before it was traded in and I was the sucker who ened up with it! LOL..LOL..

Now, I have an oil leak ..I think its the rear main seal... i don't have the money to have the thing pulled and replaced..do any of the engine oil leak sealers work? I gotta keep this jeep running at least untilnext year when I can afford to get another one...

Bustedback

It may not be the rear main leaking, it just might be the oil filter adaptor oring leaking and the oil is blowing to the rear of the engine making it look like the rear main.

Tjlance1

How can I tell???

dave1123

Spray the areas with brake cleaner, start it up and watch it. Simple.

gmv93

is it doing fine when engine is cool and is it getting worse when engine is warming up? do you smell bad odor at exhaust like you did full throttle allt the times? is there erratic idle when engine is warm and is idling ok when engine is cold? if those are parts of your situation your pre oxygen sensor ise getting broken/already broken. FYI