redrocket

Need some help with a vexing engine problem that i cant seem to figure out! First off, 95 XJ with 170K manual. Owned since 1996! No engine modifications that would impact this issue.

So... About a month ago I started getting "hiccups" on the highway, and only on the highway. It was basically like the engine turned off for a second and then started back up. And the whole truck jolted. I dont have a tach but i would assume the revs dropped during the "hiccup". The CEL came on but cleared itself on restart. Since it only happened on the highway during high fuel draw, i thought a quick fix might be the fuel filter, which was overdue for replacement anyway.

Everything seemed fine until about two weeks ago when i came to a stoplight after getting off the highway and the jeep just died. I didnt even notice it- the engine just wasnt running when i went to accelerate. It didnt start and so i pushed it into a parking lot and cranked it over. It didnt even sputter. I was quite far from my house at this point so I had no choice but to take it to a shop. It wasnt sparking so they replaced the plugs, wires, ignition coil and crank position sensor to get it to spark. A couple hundred bucks later i drove it home.

Now... yesterday i was driving on the highway and the hiccups are back- and it's bad. Now it's more of a stammer. The whole truck shakes for a second and then the engine gets it self together and works normally. Kinda scary when you're driving 70. It didn't die completely and i was able to drive it home. CEL is back on too but i havent taken it to be scanned. I thought the hiccup and the car dying was related, but perhaps they are independent problems. Or at least a separate problem caused both issues.

Anyone have any thoughts on what this could be? Perhaps the computer? I know enough to check the dumb stuff first and the battery connections appear solid with a good ground. I checked the grounding strap (firewall to block) and noticed it was broken, but i had an electrical engineer friend of mine check the resistance and he said the block was well grounded. And the repair shop didnt seem to notice/care. No idea how long it's been like that too...

Anyone have any ideas? Now that i've eliminated some of the obvious issues like CPS and ignition coil?? What else could cause this?

redrocket

So everyone else is stumped too? haha. come'on. Someone wiser than me knows the answer to this...

crystalion

What does the CEL say--that will help alot.

I bought a cheap scanner OBD-II for $50.00 from Harbor freight and now its like $40. Its one of the best investments to fix all my cars . Its worth the money -U don't need a $1000 one when this one will do just fine.

redrocket

I'm borrowing a scanner from my neighbor and should be able to answer that tomorrow...

redrocket

Also, i think harbor fright only sells OBDII. I have a 95 so i need OBDI, which is a few hundred bucks at the zone...

mr baer

Look in the Haynes manual for how to test basic error codes with the check engine light.
My '94 was doing the same, reset the ecu, runs mint as.

redrocket

So my neighbor doesn't have the jeep/Chrysler plug for his OBDI and this morning i went to Napa, autozone and advance and they all do not loan OBDI scanners. Napa had a pro one for sale for $250- yea right. Looking online and OBDI scanners are not cheap. Owned the car for 16 years and never needed it until now!

And I looked in my Haynes manual and i dont see anything about a trick to check error codes. I'm not sure i understand the suggestion. Not sure how error codes would be displayed without a reader to read them. My jeep doesnt even have an LCD display on the dash.

In any event, i've stopped and started the engine so many times i'd bet the code has cleared. And no symptoms this morning.

Anyone have any ideas of what could be causing this engine hiccup??? I'm desperate

Ender

Have you replaced and/or checked out all the basic stuff? Distributor cap & rotor, spark plugs, you said you checked ignition coil/CPS.... What about all your connections, like the positive BATT cable to your power distribution box... Do you have a VOLT meter? That would really be a good tool to use to try and hunt this problem down... Hope I helped, good luck man! I know it can get frustrating....

redrocket

Thought i'd post a follow up with the solution i think/hope has solved my problem. Like i said initially, i had a broken ground strap but was still getting a decent ground, prob. because the jeep was scavenging it elsewhere. I did a bunch of research and apparently a car can sometimes work without a ground strap as the engine scavenges the ground elsewhere, say through the radio (and can cause radio interference). From research online and talking to the local Napa guy, broken ground straps can cause all sorts of mysterious problems.

My engine issue happened only sporadically on the highway. It hasnt happened since i replaced the strap but the jury is still out whether I actually solved the problem. But the truck needed a new strap anyway and it was $6, so i def. didnt make the problem any worse. Logically, it stands to reason that a poor ground could manifest itself on the highway at high RPMs as the ignition coil isnt getting enough juice to provide the rapid spark. But at lower RPMs, the ground provides sufficient current for the coil. This could also explain why i blew out my coil a few weeks ago. It couldnt handle the lack of a ground. And it died right as i got off the highway, and the highway would have put the most stress on the poorly grounded coil. (And this fits with my engine hiccup last week. I cant think of anything else that would have made a brand new coil/distributor cap stop sending a spark to all cylinders momentarily). If anyone knows a lot about automobile electrial systems, please feel free to call BS on my theory!

If it happens again my next step is to replace the battery cables. They look ok from the outside but maybe they have corroded on the inside. Hoping i don't have to replace the positive cable as it feeds into a long wiring harness that branches all over the engine. I'll post an update if the problem re-emerges or if i learn anything new. These gremlins are hard to track down and hopefully this can help others.

Kong1965

I just wanted to post and say thanks for the hours of aggravation you saved me. I had exactly this problem on the way to work this morning. Stereo kept "blinking" and the vehicle would do a little cough and then keep going. I looked down and my voltmeter is at 20 volts, then 14, then 20.

Pulled into the bank to use the ATM. Got back in. Dead. Nada. No dome light, no gauges, not ****.

Called a friend and he came and picked me up and took me to work. Did the search, read this article, went back to the parking lot, took all the grounding straps off, cleaned/scraped/sanded, put back on. Bingo.

Awesome post and thanks again!

Geren

Nor-CalJeeper

To check engine codes turn the ignition from off to run three times quickly, the check engine light will stay on and begin to flash codes the first set of lights will be tens thebsecond is ones so it look like

Blink. Blink.blink........pause......blink. blink.blink


That would be code 33.


A code 55 means no codes stored or end of codes.

buckshot500

Autozone will check your codes for free.

My 1998 was having similar issues, & it turned out to be the bank one O2 sensor in the exhaust "A" pipe.

An easy $60.00 fix.