Sudden death - engine stops, but eventually restarts normally

[br1anstorm]

Thanks to all who have replied so far. Typically, for the past several weeks the problem hasn't recurred, so I'm still mystified.

The only other slightly odd behaviour is that in the last few weeks I have noticed that, when first starting up, the engine revs slightly unevenly and idles quite a bit higher than normal for about the first half-minute or so - up around 1500 revs rather than the normal 850-ish.

If I leave it alone it seems to settle into its normal smooth idle, and the engine then runs fine. But I just wonder, after 135k miles, if something electronic is just a little bit tired, erratic, or out of whack?

 

[old_man]

Check your grounds and power leads for good connections and no corrosion.

 

[91XJRubicXD]

I know this post is a couple months out, but regardless I'll give my two cents. I have had an issue similar, but it wasn't while driving initially. The truck would start fine and I'd go to wherever, shut the truck off and do my thing. Eventually come back and try to start the truck, nothing, all electrical is working fine. After several checking ideas, baterry cables, grounds etc, moving the shifter from neutral to park etc., I found out the culprit was indeed the Neutral Safety Switch. Wiggled the shifter several times in park without actually unlocking it from park position, and sure enough it would start the truck. And to test that even further, I shut the truck off, wiggled that shifter while keeping the ignition key turned to start and it would eventually contact and start. As for the CPS, if that were to go bad, it's not just going to reflect your starting. First off the engine will turn over with a bad one. Secondly, it also reflects all your gauges as well. Your engine will turn until you kill the battery with a bad CPS without starting. I'm positive after reading the initial post about this issue, that it's the NSS losing contact.

 

[91XJRubicXD]

And now onto my own issue, which is actually strangely related to this topic. I brought my rig into a local service repair shop and finally decided I needed the A/C fixed. They replaced the Dryer, the Suction Line, and the Condensor. Compressor works fine, and now I have plenty of cold air, 52 degrees actually. I drove the truck home yesterday after having picked it up from the shop, it ran fine. Today I needed to go somewhere, headed out did my thing and came home. An hour later I go to pick up my father in law and we head out again to Lowes, well we never made it to Lowes, lol. This thing called InstaDeath, whatever happened. Out of nowhere the truck just drops power and dies. It restarts, I'll drive maybe 10 - 20 ft. same thing. It seems when it hits a bump, that's when it occurs, but I can't pinpoint it exactly. I checked battery cables, any wires that had been previously spliced, peeled off the electrical tape on those that had it, and checked, then retaped, tried driving again, same problem, will stall after a few feet. You can watch the rpm gauge drop off to 0. To me it seems like a dead short somewhere, whenever I hit a bump, it's finding metal. I can't for the life of me find the culprit. I did notice that when I got the truck home and was inspecting all the work that had been done, they had my Optima on it's side, which is fine, I had it on the side to, but in a manner it wasn't pulling wires etc. They had it to where it was literally pulling all wires, positive cable from starter, and also the wires from the main junction block where all the larger fuses are located. I need advice on what to look for here, I'm completely clueless after all my inital checking and trying to drive theories. Can that fuse block be opened, besides the top cap ? HELPPPPPP !!!!

 

[AG74683]

My '99 XJ did the exact same thing several weeks ago...

Driving down the highway, it cut off. Dash lights still on, radio still working, but the engine was totally off. Coasted to a stop, no go getting it fired back up again for a few minutes. Finally got it going and moved it to some parking lot.

Got it to my mechanic, and he replaced the CPS, and its been fine since.

 

[91XJRubicXD]

I actually replaced the CPS on mine back in November during hunting season. So I ruled that out. Anyhow, today I took it back to the shop which took me a good 35 minutes to drive a quarter of a mile, due to every bump shutting her down. They immediately threw there testers on it and said they would call me, lol. I'm sure ya all know how that works, call backs, lol, yeah okay. So anyhow, I call back a few hours later and asked how things were going. They tell me they can't find any issues, this is after apparently the mechanic had wiggled the wires by the ECU, which honestly I would have never thought that. Reason being, there was no reason for the mechanic to be on that side of the truck when he was installing the A/C suction line etc. So come to find out after having stayed up until 4:00 am puzzled and trying everything under the sun and having no success, the shop calls me back about 20 minutes later. For some reason, only God knows why, the ECU plug managed to work itself loose. I don't know if that's due to the rough riding around these damn roads or what, but for whatever reason that's what it was. They road tested it on some really bad roads, no stall issues. I just shook my head in shame really, lol. That's the only thing I didn't check on this damn rig. Well they didn't charge me, so that was cool and now I just have to restrap the Optima back down. If anyone has any good good solutions for doing this other then using the plumbing strap like I did before they cut it to pieces, let me know please. The original battery tray is gone and there's a rusted out hole under what should have been the tray. Currently it sits on top of the Optima Battery tray it came with, but a major headache to strap in. I appreciate all your guys time and comments, have a great day !!!

 

[br1anstorm]

I happened to be browsing old threads and came across this one - which I started back in 2011.

The intermittent problem disappeared for a while, then it happened again. To cut a long story short, I replaced the CPS but this didn't cure the problem. The original CPS tested fine, too. Traced the problem to a faulty coil. Most of the time it would work, but every now and again a particular combination of heat and/or moisture would cause it to quit. Eventually it died altogether: no spark at all. So I replaced the coil, and the engine starts and runs perfectly.

Just thought it worth noting this for anyone else with a similar problem: check the coil before assuming the CPS has gone bad. Apart from anything else, swapping out the coil is cheaper and easier than changing the CPS.

 

[Shorty]

One troubleshooting tidbit I can give you for my earlier post is to remove the coil(a real PITA on the HO models) and visually inspect the case for cracks.

I happened to be browsing old threads and came across this one - which I started back in 2011. Traced the problem to a faulty coil. So I replaced the coil, and the engine starts and runs perfectly.

Just thought it worth noting this for anyone else with a similar problem: check the coil before assuming the CPS has gone bad. Apart from anything else, swapping out the coil is cheaper and easier than changing the CPS.

gold star and a cookie for Jon on that one! Still not sure why it wouldn't crank, but the coil shouldn't have had anything to do with that.