Do yourself a favor and WRAP YOUR ENGINE HARNESS!!! (1 Viewer)

Joined
Aug 18, 2010
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989
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the west desert
 
 
Years I’ve been here drinking deep from the well of knowledge and experience, and I don’t know how the heck I failed to learn about this common issue, but after an unfortunate PITA experience that I realize now could have been easily avoided, I’m on a crusade to encourage my fellow eightians to INSULATE YOUR ENGINE WIRING HARNESS BY THE EGR if you haven’t done so already.

My 95 has 220k hard, but amazingly problem free miles. About two weeks ago on a long trip in middle of nowhere Southern Utah, loaded down gear and supplies, I started getting a solid misfire engine hot, under load.

I was able to quickly determine the miss was at #5 cyl. And after a long night of trailside diagnoses that included going over the ignition system, swapping components around, and even swapping injectors around (not fun), I was stumped, and leaning toward a valve seating or head gasket issue. I cut the trip short and limped home.

Once in the shop and I was able to check compression/leak down and found #5 stayed healthy and consistent along with all the other cylinders. Perplexed I thought I’d check 80 tech and quickly came across a thread that told the tale of a #5 cylinder misfire being caused by a damaged wiring harness. I cut back the 25-year-old baked insulation and...

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Joined
Aug 18, 2010
Messages
989
Location
the west desert
 
 
I could have had this fixed in 10 minutes on the trail. Better yet, I could have avoided the problem altogether if I would have made insulating the harness years ago part of preventative maintenance. DONT MAKE THE SAME MISTAKE!

symptoms as I understand:

Misfire
No start
Hard start
Power loss
Hesitation
Dies
Dying
Chugging
Won’t idle
Rough idle
Etc...

There are likely a bunch more, but here are some related threads I found on a quick search for more info:

Another EGR burned engine wire thread...

Wiring repair tips: EGR Burned 80

Infamous wiring harness issue

melted engine wire harness

Repairing wiring harness

Code P0305 Help!
 
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Joined
Jun 9, 2017
Messages
630
Location
Denver, NC
This got me as well when I first bought my 80 - it was a hell of a way to get introduced to 80 ownership!

For those who are navigating this, sometimes this issue can create issues on the ECU as well. I spent another month after finding and fixing the above issue before I figured out that the burned insulation and ensuing short also knocked out that injector's control section of the ECU. Popped in a new ECU and all was well again.
 
Joined
Aug 18, 2010
Messages
989
Location
the west desert
 
 
If you are in a position to be able to disable or delete your EGR, your harness will thank you for it.
l’m getting a puff of smoke here and there out the exhaust, leaky valve stem seals I’m sure. And 220k miles and 25 years on the original head gasket...I’ve got a few projects ahead of it, but the plan is to overhaul the head this winter, and thinking about eliminating the EGR along with it. But I like clean air too sooo 🤔
 
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Joined
Aug 14, 2019
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Location
Los Angeles, CA
Wow, good find and thanks for posting!

Any links to suggested wrap? I found this in some quick searching, but am not sure if there's a preferred or go-to option.
 
Joined
Jul 4, 2020
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Location
Raleigh, NC
Wow, good find and thanks for posting!

Any links to suggested wrap? I found this in some quick searching, but am not sure if there's a preferred or go-to option.
I've used this on my '72 bmw...works pretty well and really tidies it all up- i'd assume the fiberglass loom wrap would be better...anything is better than nothing though
 

KennyBob

suck, squish, bang, blow
Joined
Feb 16, 2017
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Location
Texas Hill Country
So what type of insulation is recommended here in this application? I thought I had the same issue just last week actually. Turned out to be a bum spark plug wire (possibly original) thankfully. Was preparing to crack open the intake manifold and clean/refurbish the injectors. I did notice that my harness is bare up there near the EGR...
 

Funner

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Jun 29, 2011
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Phoenix, AZ
 
Turned out to be a bum spark plug wire (possibly original) thankfully.
The OEM wires have date codes printed on them, quick inspection would tell the story. Many still have originals on them until owned by someone that baselines them. Mine were original when I bought my 80 about 8 years ago.
 
Joined
Jul 21, 2015
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Location
Bend, OR
 
The key thing here is to suspend the wiring harness away from the EGR pipe. Insulation helps a lot but the air gap is what really protects it. I chased this problem for a long time on my 94' years ago and it wasn't easy to diagnose.... mostly because my mud searches were for "hesitation" when they should have been for "misfire".
 
Joined
Sep 25, 2014
Messages
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Mesa, AZ
 
I am having issues with my LC and I am pretty sure it has to do with the wire harness as well and caused me to fail the smog test here in AZ. Scott Higgins my mechanic (Avid Cruisers) has checked everything else and he also believes it is the harness too. We have a known good one on the way.
 
Joined
Apr 15, 2018
Messages
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Location
Seattle
So, I did my head gasket and thought about this the whole time and decided by the time I button up the throttle body....I am just going to go overkill and use exhaust wrap. Its rated for up to 1500 degrees I think. Haha I dont care if its overkill but now I have zero worries. Even if I had pressed it up against the egr pipe on purpose, Im pretty sure it will be safer than before.
.
The first picture was my horrible attempt to zip tie it away from the pipe. FAIL. Im pretty sure my brain was cold enough to not think straight. Id been working on putting everything back together until about 2 am outside. It was about 45degrees at that time but hey, i got it done🥶

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Ocho77

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Jan 18, 2014
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Michigan
 
Shawn, that sucks man. Glad you were able to find it. Frustrating spending all that time out there troubleshooting.
 

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