I'm planning on making a custom wiring harness for my engine bay (86 SE). I have a parts car that I'm just going to take the harness off and duplicate it with new wiring/wrap/etc. Currently I have all my emissions removed so I have alot of extra wiring lying around.

My question is, what upgrades would you suggest to make?

Such as: leaving some (how much?) wiring for future upgrades or parts, upgraded gauge/insulation, new fuse box...etc...?

Also, any tips or suggestions from people that have done this before?

 

I would suggest not trying to build a replicant from scratch, but simply unwrap, strip the sections out that you don't need, clean and test all the rest, and rewrap.

Often a harness that looks in crappy shape just needs to have the external wrap replaced - the wires are often fine.

-bill

 

Thats what I did and it worked out pretty good. I was able to make the harness much thinner. If you rewrap your existing harness it will stay in the same shape so you will pretty much know where everything goes when it comes time to put it back in the car.

 

I was thinking of doing that too. However, I figure if I'm going to be doing that much work, why not go all the way? I plan on having the car for a while, so would it not be worth it to put in all new wiring (better material, gauge, insulation, etc)?

 

Thought I'd revise this post now that I've thought it through more.

Goals:

1. Improve my electrical systems functioning (better wiring, more efficient, etc).

2. Make my electrical system more reliable/reduce problem areas.

3. In general, make my electrical system suck less.


Specific Questions:

1. Should I leave extra wires for future upgrades? If so, how many/gauge/insulation... etc?

2. Would it be possible/worth it to the upgrade the existing fuse box? Covert to a breaker box?

3. Should I upgrade any of the wiring with a different gauge, insulation type, etc?

4. Any suggested upgrades that I should do while I'm rewiring my car? (Ex. switching around wiring to make something less complicated; low to high impedance injectors [which are better?])


Requirements:

1. I probably can't afford to have my car have a lot of downtime. I have parts cars with identical wiring harnessess that I can work with. My thought was to use those and then put the new finished harness in my car.

2. Price isn't a HUGE problem. I can't afford over a couple hundred, but I'm assuming that won't be much of a problem.

 

I've stripped some wiring harnesses out of several cars. You'd be surprised how much corrosion and resistance there is even with a good running vehicle.

Your idea to 'clone' the harness is time consuming but should prevent future electrical gremlins. There are only a few hundred threads concerning battery/alternator/grounding/.....problems so the issue exists.
I've actually bidded on some complete harnesses off of ebay for the same reason, to clone it. But, I haven't won an auction yet. I am surprised by the number of bidders and cost of a used complete wiring harnesses.

I don't see the need for "extra wires". If anything, I would remove any wires that aren't being used like all those test connectors and anything that isn't needed(options that don't exist).
IMO, test connections(like error scanning or idle/timing/TPS should be spliced in directly at the ECU).

I don't see anything wrong with the stock fuse box. Cost is something to consider.

The stock gauge wiring is sufficient. Just make sure you use a quality wire that is all-season proof with quality insulation. But, its up to you to decide when buying the wire. I'd only pick one gauge larger if it'll fit!

And, some wiring is overly long. You might be able to shorten or run more compact 'straight' runs which might not be as neat as a wrapped harness.

http://www.painlesswiring.com/pdfcat.asp
http://www.wiringproducts.com/
http://www.motec.com/support/wiring.htm
http://www.hotrodwires.com/
http://www.autorewire.com/
http://www.centechwire.com/catalog/index.html

 

I'm thinking that it would be best to take out the harness first, dissasemble it, then measure and see about how much wiring I need. That is, unless someone knows about how much I should get (or know a better way).

 

Well I got a wiring harness to use. The drivers side should be somewhat easy. Passenger side, dear christ...

 

Would it be possible for a harness with such corrosion and resistance problems to actually cause a complete engine failure, or just simply create annoying problems?

 

I have a 91 frame and an 88 engine with a Holley carb. I removed all the emissions and was surprised what I did not need. I was able to get a friend's FC and spent an evening with his and mine side by side. I labeled all the connectors I did not need with masking tape and fladded the ones I was unsure of. After returning his car I started unwrapping the passenger side harness from the furthest tip all the way back to the firewall. Eventually I cut all the wires except for the wiper motor. The stubs that were left I cut to staggered lenghts to prevent shorting. I then encased the entire ball in RTV to provide more insulation.
Grounding was an additional problem. I bought one of those grounding kits off of eBay and used the thicker (10 ga ?) wire for each of the grounds in the engine bay. I tapped each hole and sanded the surface to bare metal then put a thin film of grease for good conductivity. All mounting bolts were replaced with new serated flange ones for better grip. Be careful if you buy one of those grounding kits as they are anodized aluminum. Anodizing insulates and must be completely removed in each and every connection area. The results were a very neat engine bay, brighter lights, and no electrical gremlins.

 

is this car a keeper or do you plan on selling her sometime down the road?

 

I don't plan on ever selling it.