Repair or replace frayed fuel injection wiring harness?

Question

This is on a 2008 Chevy Impala, 3.5L V6, non-flexfuel. Recently got cylinder 1 misfire / ignition failure codes. An investigation revealed that mice had gotten into my garage, made themselves at home under the lower intake manifold, and chewed the wires going to the cylinder 1 fuel injector to pieces. The rest of the injectors are fine.

If this were some other kind of electronic device I wouldn't hesitate to cut out the bad portion, solder in a new bit of wire, and close up it all up with shrink-wrap... but I'm not 100% certain this would be a good idea in this situation. So my questions are:

1. Can I patch in new wires to replace the part that has been ruined, or should I replace the entire wiring harness? (there is still enough good wire between the connector and where the wire branches off from the main harness that I think I could do it)
2. If I can, do I need to make special allowances for the potentially high-heat environment? Do I need wires with heat-resistant insulation? Should I avoid shrink wrap? Use different electrical tape (or no tape)?
3. Do I need to replace the upper intake manifold gaskets while I'm there? The car has about 95K on it and the gaskets look like they're in good condition (no idea if they've ever been done), but maybe it's a good idea to replace since I've gone through the effort of removing the manifold?
4. Any other gaskets, o-rings, etc, that I should look at or replace while I've got the top off?
5. I'm having a heck of a time disconnecting the wiring from the injector. Is there a trick I'm missing?

Thanks all!

Answer 1

Just replace the injector plug. I believe it should look like this:

You can order it from RockAuto.com for ~$6 (I'm sure you can get it from many other places as well. I would soldier this in place using heat shrink to seal them up.

As far as the gaskets go, your vehicle uses the gaskets with the rubber-ish sealing portion (don't know what they are made out of). You can chance using them again if the rubber portion is not torn nor hard. It must be subtle and pliable to do this though. Personally, I think I'd spring for the extra $26 and put new ones in there. Better to get it done right in the first place then having to redo the job.

If you took the manifold off without breaking any other gaskets or o-rings, I wouldn't worry about them. If you have broken them loose, I'd plan on getting them replaced along with the manifold gasket. When I take a manifold off of the heads, I try my darnedest to keep everything together that I can for two reasons: less nuts/bolts to keep track of; easier to get everything back together.

I personally have not taken this type off connector off of an injector before, so your guess is as good as mine. Once you get the new connector, it should be very self evident as to how to pull it off. I do know they can be a bugger, but usually it isn't too hard. Don't force it off, though, as you'll end up breaking an injector and that'll cost you another $50-60 to replace.

As an aside, if you are going to leave your car sit for a length of time in the garage, put a couple of dryer sheets in strategic places under the hood. Mice don't like the smell, I understand, and will leave your wiring alone.