Disintegrating Wiring

B6/7 S4/RS4
#1

You know that wire on the firewall ground connection behind your intake manifold that falls apart on every S4?

It is the ground for the Secondary Air Injection motor (located underneath/behind the p. side aux radiator). And it is absolutely terrible shape (brittle shielding) through the entire harness.

Also, the other wire from the SAI motor, a red on that runs all the way through to a relay connection under the ECU, is in equally as bad shape! You just can’t see it since it is inside the loom.

I found this on my harness. Green in the brown ground connection wire that everyone tapes up. Yellow arrows point to the red wire from the same SAI motor plug. I even bought a Used harness… splitting into that one, the same wires - BOTH of them - have the very brittle and disintegrating shielding.

http://audirevolution.net/addons/albums/images/183816628.jpg

http://audirevolution.net/addons/albums/images/409918254.jpg

Not sure the point of the post really other than an FYI. :smiley:

#2

That really is strange since you’ve noticed it on multiple harnesses. Wonder what the cause of that could be.

Also, if you think that’s disintegrated wiring, you should have a look at my engine bay

https://uploads.tapatalk-cdn.com/20170619/9cc876016e0eb542d5106a7cd807cb49.jpg

#3

Yeah, the wires themselves actually look OK, it was more the shielding was brittle as sin and you look at it sideways and it flakes off.

What happened to your wiring? :o I know the s4 engine bay gets warm but mine generally stays flame free :smiley:

#4

Perhaps Audi used a different wire coating when adding that specific wire to the loom. One that isn’t as resistant to the high bay temps

As for mine, I’m not so fortunate as to remain flame free. My crappy Delphi alternator caught on fire and lit a bunch of stuff up. Here are some pics of what I took out and replaced if you’re curious. If you look closely you’ll see it even melted a hole in my JHM oil cooler lines and that’s where a bunch of oil dumped out right before the firemen put the fire out

https://uploads.tapatalk-cdn.com/20170620/0352b2e7c275ec6b94fb31bd75fa403a.jpg

https://uploads.tapatalk-cdn.com/20170620/afa294d209d5036edad0cf2c74028600.jpg

https://uploads.tapatalk-cdn.com/20170620/b8a25c6899ab60b6e16e3261d38a1fa3.jpg

Sent from my potato

#5

WOW that is crazy.

I have seen several cars that have cracked issues with the wires on the SAI wire run but what you just showed is crazy.

#6

WOW. Well maybe this is going to be part of the issues you have been having.

#7

Mine was in the exact same condition. I actually completely removed the two wires and ran new wires point-to-point to replace them, with a heavier gauge. The simple theory is that the wire gauge is not sufficient for this circuit. However, there is a massive 60A fuse on this circuit, and wiring of that gauge (typically) is rated for 65 to 70 amps. Next to the positive wire is another major power supply wire of the same gauge for another circuit, and it is completely unharmed. It seems odd that Audi would have a different supplier for two wires of the same size and insulation color in the same harness. As for engine bay heat, those wires are just as close to it as the rest of the harness. A fairly robust harness sleeving with heat resistance properties is used for these harnesses.

In any case, my new wires are holding up thus far, so it may just be low-grade wire quality on a high amp circuit.