Ignition/injector problem?

[Joenavy85]

Had an interesting occurrence just now. Got to work, parked in my usual spot, ran the trans cooler fan for about a minute and then shut the engine off. But, after turning to that first click the engine ran for about 4 seconds before stuttering and stopping. I turned it all off, pulled the key out and then put the key back in and started it up. Fired up just fine, I let it run for about a minute and then shut it off again. This time with no issues. Never had this happen before, or even heard of it happening in a gas engine (fuel injected at least). Any ideas?

eta: 2005, 3.7L, 181k miles, regular maintenance (most recent was replacing the PCV valve 2 weeks ago)

 

[LibertyTC]

Could be an ignition contact problem, at which point you may have to replace the IGN switch.
You could try lubricating the tumblers with a graphite based spray like Lock-Ease & see if that helps.
Alternatively, I have dipped the Key in ATF+4 which is a good synthetic & tuned the key back & forth.

 

[Joenavy85]

Did it again today when I got home. I've been watching for it to see what everything does. Turned it off 1 click and the gauge cluster turned off as if the engine shut off, but the engine continued to run for about 4 seconds. I thought maybe the ASD relay was sticking, but I think if it was the gauge cluster wouldn't react to turning the key. I'll try to get in there this weekend to look at the ignition contacts. From now on I'll also turn the key all the way and remove it instead of seeing what it does at the first position.

 

[Joenavy85]

Did it against this morning. I pulled the ignition apart yesterday, cleaned up the contacts and put fresh dielectric grease on them. I pulled the ASD relay yesterday, contacts were clean on the outside. I knocked it around a little, in case something was sticking. I've got nothing at this point. So far it's not really an issue, just a minor annoyance. Anybody else have any ideas?

 

[LibertyTC]

Has there been any recent lighting /electrical work done to the Jeep or added aftermarket equipment?
Are all the light bulbs working?
Make sure you have zero corrosion & tight battery terminals, nut tight for wires @ alternator.
Is your ground strap in good shape?
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[Joenavy85]

Added a bigger trans fluid cooler with fan, but I used the wiring I already had in place for my LED fog lights. Same switch, same grounding point. All the lights are working, I'll have to wait until I get home to check the rest.

 

[Joenavy85]

Connections are all good, terminals clean. On another post it was suggested to swap the ASD relay out. Did that for the drive home yesterday and it shut right off. I'm going to leave it like that for a few days to see if that's the issue, since the problem has been intermittent.

 

[Joenavy85]

Think I may have found the problem, though it will take a little more scientific testing to be sure. Drove home yesterday, and it shut off just fine. This morning it did it's funny business again, HOWEVER, this morning when I shut it off I had the fan for the trans cooler turned on. When I drive home tonight I'm going to have the fan on again but I'll see if shutting it off right after turning the ignition shuts it off sooner or not. Should be interesting to test.

 

[Joenavy85]

Did some running around yesterday, which gave me a chance to test my theory. Every time I had the fan on when turning off the engine it continued to run. As soon as I turned off the fan the engine shut off instantly. I can't come up with any reason why it happens. I'm using one of those "add-a-fuse" parts and it's in the PCM fuse slot (obviously the reason), which is easy enough to change. I just can't figure out why it would make a difference. Only idea anybody I've talked to could come up with was that the family motor has a capacitor on it that's feeding back to the PCM. But I feel it would require a big capacitor to keep it going for 4 seconds. Any other ideas? I moved the add-a-fuse to a different slot to avoid further incidents.

 

[Joenavy85]

UPDATE: Since moving the Add-A-Fuse I haven't had any issues with the engine shutting off. Out of curiosity I went ahead and swapped it back and left the fan on, sure enough, it ran for a few seconds and then shut off. Problem solved, but the mystery as to why that was a problem goes into the unsolved box.

 

[Billwill]

You would need to closely go through the Wiring Diagrams to see what was going wrong...no point now as the problem is resolved.

Weird electrical problems over the years put food on my table and a roof over my head but also gave me grey hair!:emotions34: