Hi again everyone. My 1988 has been having trouble starting recently. My mechanic friend looked at it and saw that it was getting fuel, but not spark. I replaced the entire ignition coil module (ICM) with a used part from a junkyard.

Initially, that did not fix the issue, since that first junkyard part *may* have been defective. I bought a second junkyard ICM, and my Jeep started immediately after I installed that part. It worked without issue for a week or so. My mechanic friend told me I should have just bought a new part, but since he believed I needed the entire module, and not just the ignition coil, I bought used to save a substantial amount of money. Thinking about it later, I bought a brand new ignition coil for $16 (just the coil, not the lower metal module.)

My XJ started and ran fine for that first week. Then I stopped for lunch and left the Jeep in the parking lot for 15 minutes. I came back and the Jeep wouldn’t start. Luckily I had the brand new coil and all the tools I’d need in the Jeep, so I swapped the coil and the Jeep was able to start.

Maybe 2 days later, I drove the Jeep to work. Came back to the Jeep 8 hours later and it wouldn’t start again. I no longer believe it’s an ignition coil issue, since I’ve changed that several times now, most recently with a brand new Delphi coil from RockAuto.

Just looking for any insight here. I am not a mechanic, I bought my XJ less than a year ago partly because I wanted to learn about cars and thought this would be the perfect vehicle to help me pick up some knowledge. I’ve learned a lot through YouTube videos and my mechanic friend. He thinks it might be a loose connection related to the ignition coil? Has anyone had an issue like this, or knowledge that might help me out here?

Right now the Jeep is at my place of work. They don’t mind, they know I’ve been having trouble with it, but I know eventually they’ll get sick of looking at it in the parking lot. I’ve been biking to work this past week, which is fine since it’s only a 45 minute bike ride to work and I like the exercise. Still, it would be nice to get my car up and running. Any help would be greatly appreciated.

Thanks,
Packy

 

Also just to mention, I have also replaced the starter on this Jeep this past week. That didn’t help. My mechanic friend told me that was pointless since we know it’s related to the ignition. But I had already ordered a starter and figured I’d give it a shot.

Also, the Jeep currently starts sporadically. I was able to move it to a place further away in the parking lot, out of sight, the morning after the most recent non-start. So it’s definitely an intermittent issue. It had also happened a few weeks ago, where I parked it in my parents driveway and couldn’t start it after having been in their house for 20 minutes, but I was able to start it the next morning.

It starts sporadically, both before and after the new starter was installed, so I know I installed the starter correctly.

But since I live in the city and they sweep the streets around me on Fridays, I have not been willing to risk taking it home and not have it start on a Friday morning when I need to get to work, and also risk a ticket and tow.

 

A new ICM is quite expensive, so it is understandable that you are trying used. It may be worth your effort to both clean the contacts of the ICM that the coil clips into and also squeeze them together while the coil is removed so that the clips grip the coil's studs firmly. However, you may be having issues with an intermittent (failing) Crankshaft Position Sensor (CPS). Although this is not a permanent fix, next time it doesn't want to start, pull the CPS connector apart and put it back together. Often the vehicle will start after that - and it would also indicate that you need a new CPS.

 

Thanks for the response. I forgot to mention, I replaced the CPS with a brand new unit a month ago, right after I had installed the initial junkyard ICM. That did not fix the issue, but the Jeep has started since then (intermittently) so I know I installed the CPS correctly. (And let me just add that the Jeep wouldn’t start when I changed the CPS, it was on a gravel parking lot, and I changed it on my back without jacking the Jeep up, and the Jeep is stock height. That was fun. I recorded most of that incident, I should put it on YouTube eventually.)

I also bought a new ECU before we had narrowed it down to the ICM. I replaced with a new ECU. Same thing, it didn’t fix the issue, the Jeep has started since then so I know it was installed correctly.

As for your first point, cleaning the contacts. I had noticed the module was dirty so I sprayed it with QD electronic cleaner (NOT electric parts cleaner, it was just what I had on hand.) Could it just be I need to spray it with the correct cleaner? Or are there any wires that go further along that need to be replaced?

I have also replaced the distributor cap, spark plug wires, and spark plugs within past 3 months.

 

Or are there any wires that go further along that need to be replaced?

This is probably the real question and direction this will be heading. What, if anything, have you done so far with the grounds on and around the engine? And is the C101 connector still in service on your XJ?

 

Ok I agree I think you may have just pointed me in the right direction. Maybe 5 months ago, I had trouble starting the Jeep after work and I was able to diagnose it myself through these forums as a C101 issue. I scraped out the gunk and sprayed the connectors with cleaner. I was able to start the Jeep, and I drove the Jeep daily for a few weeks after that. I had assumed the C101 issue was separate from my current issue because the symptoms that day were a bit different. I could start it, but it would die as soon as I shifted out of Park. But once I cleaned the connector, the Jeep started and I could drive it.

I am aware of the “C101 Elimination” online and I have it on my long-term, “when I get to it” list. But I wonder if it wouldn’t be a good idea to do it soon if it’s a related issue.

I haven’t done anything with the grounds on the engine. I vaguely remember reading something about how these Jeeps should have had more grounds than they came with as stock vehicles, but I didn’t think much of it at the time. I’ll try to find a YouTube video of someone adding grounds on an XJ tonight.

 

Check this out: cruiser54 | True tales from "The Book" You'll be interested (first) in Tip 1, (maybe Tip 2 soon), Tip 4 for this current thread, AND Tips 5 and 6 for the remaining grounds questions.

 

Tips 1 through 5 need to be completed before anything else.