What wires do I absolutely need for an 83 V12 to run?
The problem: I replaced the engine and it runs very rich. Sensors are working, switched ECU's several times and it already has a new fuel injection harness.
So, I unwrapped the rest of the harness and found broken wires and cracked insulation everywhere. I'll be replacing most, if not all of it...but...what wires can I delete?
In the state I live in, my 83 doesn't have to have emissions. I've already removed the air pump, the cruise control and the A/C.
I figure I need the ATS, CTS, TPS, the 2 micro switches on the capstain, O2 sensors, coil, amp and Tach and if I remember right, Doug said I needed to keep the 2 wires going to the blue vac sensor thingy on the right side that I have no idea what it does.
Advice?

 

Anybody?

 

Jamey,

As you know I did mine 10+ years ago, and I dont reckon I really eliminated many wires at all. You will need as Doug said all those sensors, and the EFI wires to and from the resistor pack.

We only have 1 micro on the capstan, and it is wired in sequence with that blue/white "thingy" as you call it. Both those items are responsible for acceleration enrichment. The micro is self explanatory, the blue/white uses vac to keep the contacts OPEN, and they close as vac decreases (acceleration mode) and gives "about" 12% enrichment.

I found the same lousy wire integrity, and that is what led to the TOTAL rewire of the engine bay, and the removal of MOST of the electrical items outside the engine bay, so a really HUGE ateration from the way it was. So as far the engine bay is concerned, I have less wires IN there, but the total wires in the system is probably the same, or very close, just outside the bay.

You could do without that shielded wire, IF you bridge the fuel pump relay socket so it runs with ign ON all the time. OK for temp workup, but too dangerous to leave like that.

 

I'm a little confused about the shielded wire, I assumed it was shielded to protect the amp from being triggered by the nearby coil. What does that have to do with the fuel pump relay?

 

Aha.

That shielded wire sends a signal TO the ECU to inform it that there is "ignition pulse" happening, so it is OK to keep the fuel pump and injector circuit "alive".

That signal is sent FROM the ignition amp.

The shielded wire was to stop inductive interference messing with the transmission of that ignition signal from the amp to the ECU, nothing more. The ECU is a tad fussy with "fuzzy" signals and becomes erratic. I believe the main inductive interference of Jags concern was from the spark plug wires at the rear of the engine????.

With my amp out the front on the RH side and the wires running up the RH inner guard to the terminal block at the RH lower bulkhead, they are nowhere near inductive items, so I dont run a shielded wire in the engine bay.

The shielding bit is earthed at ONE end only. Earthing it at both ends apparently reeks havoc.

 

Ahh...so if I move the amp to the firewall, near where the harness enters, I can delete the sheilding? That would be a help! Let me know...

 

Maybe.

The amp needs to be kept cool, and outside the engine bay in a draft is my opinion on that.

Mine is out the front of the radiator on that same panel the 2nd coil was mounted on, but on the RH side.

I extended the 2 wires from the distributor, and the 2 wires from the coil (I only run 1 coil), and the tacho signal wire, along the LH side of the fuel rail, across the rear of the engine bay, behind the brake booster (RHD), down the RH inner guard (wing) to end up at the amp.

I replaced the shielded wire with a suitable gauge wire to the connector at the RH bulkhead (in behind that removable panel at the rear of the wheel arch), where I found the shielded wire, obviously, and it was in as new condition, as it has never seen engine bay heat in that area, and soldered the new wire to the thin inner wire and used heatshrink to insulate it, and that was it. Mine has that shielded wire earthed at the ECU, so that outer woven stuff was stripped right back, so NO chance of it ever contacting the signal wire.

I will PM you my Kodaks of the amp etc, as my record of attaching them here is zilch.

My mate in Melbourne has a 1988 S3 V12, and his amp is under the passengers seat (LH down here), mounted on an alloy plate with a 12v PC fan just in case, but since the car is airconditioned the cabin is real cool, so the amp is happy. Been there 2 years now, and is his daily driver, and no more silly cutting out, or other female moments.

 

I opened up that kick panel on the right bulkhead side and looked for the shielded wire, but couldn't find it. I found a bunch of 3-wire connectors, and a few single wire connectors, but nothing that resembled that shielded wire. Maybe I better look again...