Finally fixed “maybe” misfiring

[BAULSAUL]

Third trip to the dealer might have done the trick. Somebody might’ve gotten a little motivated at work and decided to use a scope instead of switching coils and plugs. Turns out the wiring harness was rubbing right against the engine. Caused an electrical shortage to the ground and also created the massive amount of misfiring on cylinder number one. Also caused every single warning light to come up on my dash from time to time. Obviously, I had a lot of shaking and vibrating when the misfiring happened. It would come and go. Engine light would stay solid when I was in higher gears and it would flash when I got down the first gear obviously. Dealership drove the car a few trips today and threw some miles on it and everything seems fine. They’re going to do the same thing tomorrow and I hope it is finally resolved. I just bought this truck two months ago and I was iffy at first, but quickly fell in love with it. But, if this thing ends up in the shop one more time for this issue, bye-bye, Jeep.

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[Brahmajoe]

What wire was touching?

 

[tysongladiator]

Had that issue in one of my Broncos. Thousands of dollars later, one shop washed to take a look. They said, turn the engine over. At the same time, they were turning the shop lights back on. While it was still dark, they saw a wire from the distributor arcing against the block. Put on a butt connector and never had an issue again.

 

[Brahmajoe]

Third trip to the dealer might have done the trick. Somebody might’ve gotten a little motivated at work and decided to use a scope instead of switching coils and plugs. Turns out the wiring harness was rubbing right against the engine. Caused an electrical shortage to the ground and also created the massive amount of misfiring on cylinder number one. Also caused every single warning light to come up on my dash from time to time. Obviously, I had a lot of shaking and vibrating when the misfiring happened. It would come and go. Engine light would stay solid when I was in higher gears and it would flash when I got down the first gear obviously. Dealership drove the car a few trips today and threw some miles on it and everything seems fine. They’re going to do the same thing tomorrow and I hope it is finally resolved. I just bought this truck two months ago and I was iffy at first, but quickly fell in love with it. But, if this thing ends up in the shop one more time for this issue, bye-bye, Jeep.

What wiring harness was rubbing?

 

[AmosMoses]

Great news. Fingers crossed that was the culprit.

 

[ShadowsPapa]

Third trip to the dealer might have done the trick. Somebody might’ve gotten a little motivated at work and decided to use a scope instead of switching coils and plugs. Turns out the wiring harness was rubbing right against the engine. Caused an electrical shortage to the ground and also created the massive amount of misfiring on cylinder number one.

Refresh my memory here a bit if ya'll would. On the other posts about this thing, was the word "scope" mentioned by anyone?

They can literally watch the pattern of anything, including O2 sensors, with the right equipment. They can check for any electric irregularities.

They can even check the pattern to an individual injector -

Or in some cases, a coil pack's primary can be looked at.
Someone good with a scope can really tell a lot - even about the health of an electric fuel pump.

 

[BAULSAUL]

Here’s a breakdown of the work performed. I mentioned using a scope on day 1, but they are morons. They drove it 100 miles. Left me with zero gas. I went and bitched so they filled it up. Just like I filled up the loaner. 45 minute drive home and only a couple misfires total. Maybe someone can break this down for me ,.,,,,,

 

[BAULSAUL]

I have no idea what wires were touching. I am somewhat mechanically inclined, but I don’t know much about electrical. I can change the oil and fluids, etc., but not electric. I was hoping somebody would be able to tell me what happened by reading the mechanics notes.

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