Dies hitting boost after harness swap(UPDATE) FIXED!!

[alexandermf]

Sooo after I was about to swap another crank sensor since everything else was fine I noticed the harness where it connects to the engine side was busted... Melted and cracking from turbo heat. Now question....

As i was pulling the harnesses shitty plastic tape off I noticed one wire that's broken off that Idk where it leads... I'll get a pic tonight but to visualize, the cam and drank sensor harnesses that run off the engine run together in a bundle and that single wire is running with their bundle but too nothing




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[Bartek]

Alex, are your symptoms still the same as earlier? No CEL? Any relays clicking?
Did you try to replace your ECU? At least for a few days?

[alexandermf]

I'm pretty sure its this wire that's burnt/broken off the crank sensor harness. I'll be extending it and repinning back into the harness. Still no cel, I honestly think my bulb is burnt out

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[alexandermf]

And to answer question from earlier yes we did change ecu here's a list of everything we changed from wheb it FIRST died:

Cam/ crank sensor
Ecu
Fuel pump
Fuel pump and ignition relays
Ignitor
Timing belt
Coilpack and spark plugs

Second time it died I switched the ignitor to my first one we took out and it started up

Now this third time I believe is the wires that aren't burnt from turbo

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[Legacy777]

Yeah, it sounds like it's a wire issue.

My mom's 90 Toyota pickup had a similar issue, and she finally found a good tech at a dealer that diagnosed it to a wiring harness problem near the exhaust manifold/piping. They replaced the wiring harness and all was good.

[alexandermf]

Ya... I'm thinking the turbo cooked the heck out of those wires... I worked on it all morning, couldn't get spark till after swapping everything and connecting the wires. Getting it towed up to Denver where a couple members on here have a garage and can diagnose it quicker with the right tools. Theyll have it for a week so hopefully they find the real problem

The wires coming off the harnesses were so cracked and brittle, like crumbling in my hands

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[alexandermf]

Soooo I guess the guys up in Aurora have started yanking lots of random wiring I guess under the dash was a mess. From what they tell me so far they are getting it to start then it warms up and dies...? Each time I guess, so any ideas? Would s certain wire possibly shorting out when the temp is getting too hot for it?

[topsecret888]

I'm mildly surprised that with all these problems ur getting and having to deal with, ur still persisting with this car. Perhaps it's time to call it quits and sell it? Get another SS or something else that's not so problematic? I know these cars are incredible and ppl who knows love them, but sometimes if things just don't work out, it simply won't. If u have the funds, y not look at the older WRX? They don't cost that much now, and everything's obd 2 which can be easier to work on.

I also had intermittent/random starting issues with my non turbo legacy wagon, it's a 91 and I did the usuals, replaced the starter and battery and still having the same troubles until my mechanic and I found out that the grounding cable from the starter to the battery was toast. Had it replaced and the car runs fine now. Keeping my fingers crossed that nothing else was there. Another thing i need to mention, my check engine light was on and after that, the engine light had gone off on its own.

[Legacy777]

That's interesting about the temperature related issue. I almost suspect it's a wire in the engine bay and that when it gets hot it loses conductivity. I would check things like the crank & cam sensors, as well as ignition. I'd be more suspicious of the crank & cam sensors, but it's certainly worth checking the ignition system. Don't forget about the power supplied to the coil & igniter.

[alexandermf]

Yup sounds like thats what's happening. Boys up north says there's an intermittent break in the wiring harness from fuse panel under hood to the one under dash... It's gonna get deep and messy hahah

[alexandermf]

Well its been another week or so and had to send to another subie shop cuz the shop that just had it is confused as well. From what I hear they could get it to start sometimes and when it did it would idle fine until any load applied then it would cut out....
Should be hearing from other shop any day now, I'm wondering if it would just be smarter/easier to buy a used working engine wiring harness and just replace mine?

[Legacy777]

That may not be a bad idea, but one thing to remember is that the crank, cam, & knock sensor wiring does not go through the engine harness and is routed back through the bulkhead wiring harness to the ECU.

So depending on where the issue is (if it's not in the engine harness) swapping just the engine harness may not do anything.

[alexandermf]

So which part/how much of a wiring harness part I should be looking for?

[Legacy777]

If the crank, cam, & knock sensor wiring is bad it's part of the main body harness that goes in behind the dash. If this needs to be replaced, I'd suggest pulling those shielded wires from the main loom and just routing them to the ECU vs trying to swap the main bulkhead harness.

[alexandermf]

Ya I started pulling them from the main harness before I towed it to Denver in the first place, thing is no one knows still which wire is breaking... It could be one of the wires from fuse panel under hood to under dash, there's just been sooo much that has gone wrong electrically that controls spark and fuel and whatnot from when it first broke down in late september up to now that we have no clue which area to focus on or if I have multiple wire breaks here and there

[Bartek]

One hint - if you have the same symptoms as me - which means no CEL at all, try to find wire/s at ECU perhaps. I mean, check all grounds and all live power going to ECU. Then try to deliver ECU all things it needs - using for example needle with power or ground supply. There can be about 8-12 wires like this I suppose.
Then I would check if CEL is on. If it is, I would try to unplug one by one 'additional' power and ground support and check when CEL dissapear.
I know, it's tricky and it could have no sense...just guessing. Keep my fingers crossed.

[Legacy777]

If you suspect somewhat your entire harness, then it may be better in the long run to try and find a good harness to swap into your shell, if that's something you want to do.

[alexandermf]

Well what would you do to get it back on the road again quick? It's been down so long for being a daily driver and we've tried everything else, so if buying a new part of a harness will fix it I'm def willing to do that

[Legacy777]

What I would probably do is rerun just the specific wiring I thought was bad. The key components would be crank, cam sensor, knock sensor, ignition, and fuel injectors.

If you suspect the crank or cam sensors, I'd start with those. You can use microphone wire since it's shielded and just run new wiring from the connector below the throttle body to the ECU. I would definitely suggest replacing or verifying that the crank & cam sensors & their wiring is good....if you haven't done that yet. If you still have problems, move on to the ignition wiring from the ECU to the igniter. This wiring doesn't need to be shielded.

That would be the "fastest" way to do it. The best way would be to get a new harness.

[alexandermf]

Alright well ill try and start locating a harness I suppose for now, any idea what a good used price would be?

[Legacy777]

No clue....

[alexandermf]

Ok well ill keep you updated! Hopefully this is the fix once I find a harness. My current one must be cooked to shit in multiple points. The guys who have it now said its for sure a break in the harness dealing with repower to ecu whatever that means

[alexandermf]

Someone has one from a 5mt with metal maf, can this work?

[Legacy777]

Depending on what harnesses you are going to replace, you are going to likely need one out of a turbo auto. The non-turbo will probably have a few differences, as well the MT against the AT. However I couldn't tell you what all those differences are going to be....and if there are truly any differences.

The only way to tell for sure is to compare the harnesses.

[alexandermf]

Well found a local with a harness from a turbo wagon,getting it tomorrow!

This trouble with the wires cooking/heat soak from IC needs to be documented... Happened to one of the guys working on my car now! Especially once these cars get into higher mileage