New old guy and dogie need help!

Buddy

New member
Hi folks,

First, this is my first thread here... me and my dogie Buddy acquired a 1997 Cherokee Sport back in February. It's a great find and something we both have needed. About a week after we bought it, we had 30" of powder fall and it was flawless... it worked and got us around without fail. And by the way, it's Buddy's (my dogies) jeep... he takes pride in his new buggy, loves the room and the front seat!

It has 155k miles, one owner, maintained very well and we were very happy with the find. It's our pack mule and gets us out an about regardless of the weather...

Until... about a month ago after a fill up and a few miles, it started stalling, stumbling, erratic idle on deceleration at the first stop. Okay! Bad fuel witch is a very common thing is these parts... So from previous experience with nasty fuel, a can of Sea Foam. No big deal! After the additive, it improved slightly but it continued to have the same problem. No CEL displayed so we figured it would just take a while for the "cleaner" to work witch it usually does. Then, it started stalling/stumbling on acceleration once the symptom started and popping as an intake backfire and finally the CEL came on. I checked the on-board diagnostic feature and it gave a reading of 12, 21, 55... battery disconnected, O2 sensor malfunction, end. Okay, the O2 is bad but that didn't make sense from what I know about it... it's a sniffer and from what I understand if it's bad it will cause poor performance which it has now but it shouldn't cause a "backfire" so to speak. Then the light CEL goes out and it run horribly... it has new cap and rotor, new wires, new spark plugs which I replaced when we got it along with oil change and coolant flush just to have a ground zero to work with. So I don't think any of that is an issue. It's actually cheap insurance so I figured, why not. I had to remove the batter to clean the tray and when I did, it reset the CEL and the codes disappeared. For 26 miles... then it started all over again. Stall, stumble, pop, snap, lousy performance, horrible gas mileage and then the CEL came back on... checked the codes again and they were the same... 12, 21, 55. I've checked everything I know how to check via Haynes manual... connections, loose this or that, but have no clue to what is causing the problem. Everything checks out!

What am I missing? I've read endless posts from many different sites and found nothing that seems to help. The local garages just want to start replacing parts, the folks at the auto parts place have no suggestions other than what I have already done and Buddy is really getting annoyed that we can't take our trip into the hills for a much needed respite... It will run wonderfully for a few miles, then the pop, pop, stumble, light goes on and it's performance falls flat. I can feel when it's about to happen because it will start to slow, the light comes on and then the pop, then the stumble. If I try to accelerate, the pop in the intake will increase, if I let it idle, it stumbles and stalls but won't completely stop running but it is a complete dog... :cry:

Help... does anyone have any suggestion. Buddy will be a very grateful Jeep owner.

Hope this makes sense!

Chet and Buddy
 

Follow the ground cable on the battery to the stud in the cylinder head that it attaches to - take the nut on the stud off and then remove the stud - clean the threads, loctite them and reinstall making sure the stud is tight before putting the battery cable back on and tightening it up.
The stud loosens up and causes intermittent loss of battery power to the ccar.
I chased this one for a couple of months on the Comanche that I have.
Good luck!
 
I would check the fuel pressure first. Low fuel pressure can trigger an SES lamp from the O2 sensor detecting a lean burn.
 
Hey Guys...

Thanks to both of you...! And I apologize for not replying sooner. The reason is... Both of you made me think about what was happening and I sank into the "lets check all this out mode".

SteelHeadz... From what I researched before while on this trek, I knew that could be an issue. I didn't have a decent gauge so I postponed it. So when I went to town the other day, and by the way it's 20 miles to town, I picked up a new gauge. I have lots tools and gadgets anyway but I really wanted a decent pressure test anyway. It took about 30 seconds to hook it up and it answered the question almost immediately. It said I have 50psi of fuel pressure on the rail with ignition on and pump started. I waited about 10 minutes and it still read 48psi. No leak down issues at all. I started the engine and it immediately jumped back up. Turned it off and it repeated the same information in about 10 minutes. I have good fuel pressure so that question is answered...

FREDMCGUIRE... What made you think about that? Bingo! I traced the ground from the battery back to the engine which I had already done anyway but it looked okay! It's a buss plate with 2 studs that screw into the block and on top sits the ignition coil. But after your comment, I took another look. I noticed a bit of "white dust" on the terminals at the end of the wires and on closer inspection and better light, I noticed what appeared to be the residue of a varnish like sealer. Okay, no big deal... wrong! The entire ECM and all of the components that make up the deal ground on those studs. So, I disconnected everything, removed the studs, cleaned everything and put it all back in place. I had noticed an erratic behavior in the gauges when the problem presented itself but I just thought it was because it was stalling out... Anyway, it immediately started up clean, a little rich which it always is at first, it idled smoothly and everything was very happy unlike before. I've driven 110 miles thus far... it shifts better, it idles better, it still gets horrible gas mileage but that's what it does anyway. I rechecked everything... all the sensors have proper voltage and action except for the O2s... the sniffers! They are original and need to go anyway so that is a given. However... the fix fixed it.

How did you discover that? It makes perfect sense that if the ground is faulty, the ECM and all the sensors will give bad information.

Thank you both!

We owe you some beers!

Cheers... Chet and Buddy
 

Hey - glad I could help.
I've had plenty of cars and trucks (Jeeps and others) that have suffered from 'loss of ground' problems - an easy and cheap thing to fix.
Once on a Chevy truck of mine, the positive battery cable corroded entirely away inside the plastic cover, insidious stuff, corrosion.
Happy trails to both of you.
 
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