looking to get some input. did you buy the wiring harnesses or rewire your stock setup? if you used the Fast wiring was it wroth it? any snags? was it all labled properly and how did you get your sensors tied back into the dash?

 

I put BS3 on a 1993 LT1 Camaro w/ Optispark, 383, AFRs, D1R, so I may be able to help a little.

On that car, the only gauge that needed attention was the speedo. The factory setup is a permanent magnet AC frequency generator sensor that sends vehicle speed to the PCM and the PCM buffs the signal and sends a 4000 pulse/mi switched pulse to ground. I used a Dakota Digital SGI-5 interface, grounded one of the wires from the VSS, ran other VSS wire to the signal input on the SGI-5 and used one of the outputs back to the instrument cluster. I calibrated it while the car was on the dyno. Worked perfect.

The AC on that car used a high side pressure tranducer and PCM controlled compressor clutch, I replaced the transducer (sensor) with a regular 134A high side switch and rewired the AC like an older car (high side and low side swiches control ground on compressor clutch, power fed from AC relay). I did have to add another relay to activate the AC realy, since that car's PCM actually ground activated the AC clutch relay and the HVAC control was a 12V (+) request signal to the PCM. I could draw a diagram if you plan to use AC and have the same setup.

The Optispark wiring was simple with the BS3 and worked flawlessly. NOt sure what XFI uses, but I bet it's very similar. I did have to add a MSD igniton box after a couple dyno pulls though, because it was hitting a brick wall at 5700-5800 rpm. A regular 6A ignition fixed that instantly and allowed the car to pull up to the redline (6600). It picked up about 50 rwhp too, all up top.

 

Isn't the PCM on the LT1 located in the engine compartment? I think none of the aftermarket ECMs like being mounted in the engine compartment which would force you toward buying the FAST harness.

I did my own harness for my 93 Cobra by re-pining the factory harness but the factory ECM was located inside the car. You really need to be familiar with making harness to make a FAST harness because they aren't and can't help you. Both guys I spoke with on the tech line that I asked for the crimper part number told me that you just squeeze the pins with needle nose and solder them. I knew after that that I was on my own.

 

I just finished assembling a FAST flying lead harness.
It is a lot of detail work but the two prints they give you are easy to read.
There are multiple splices within the harness that have to be soldered and sealed up.
I probably have 4 -6 hours in it but I learned a lot too.
I got a nice locking crimper for $ 78. from a local electric supply and it worked great.

I mounted everything on a piece of plywood as this is going to screw to the back of the seat in a boat.
It's more functional than show.
I have a toggle switch to mount up yet that will let me arm the internal datalogger without the PC attached.

For all the work that this harness was I have the length of the leads right on as compared to a universal harness that has coils of extra wire.
I had that before and it worked fine but always looked messy.

I intend on installing this in the next couple days and when I get it connected to the PC then I'll see how accurate my work was.

#ad

 

That is a CLEAN setup! what is the "flying lead" harness? and what did the FAST come with outa the box? Im not at all intimidated by wiring itll save me about 500-600 but I want to make sure that there isnt any funky connections that would keep me from merging my hybrid LT1 harness to the FAST.

 

A flying lead harness just means that there are no terminals or plugs on one end of the wires.
All the wires come out of the main plugs that go into the ECU.
You need to figure out all the lengths yourself for your application.
Each wire in the harness is printed on the side of it what it goes to so theres no question about it.
I think most guys buy the harness already made up and don't get to have this much fun.

Thanks for the comment, With all the show quality stuff on here I was afraid I would be laughed out of town.

I started out with a left over piece of drywall and laid out all the lengths and locations of the ECU, fuse blocks, and relay and drew it out on there.
Then I grouped the wires together as to what they went to and put a piece of masking tape around them and wrote what it went to on it.
I located the components on the sheet and put screws into the drywall sheet to keep them from shifting around.
When you start out with a hairball like this keeping things grouped together helped me a lot.
I also got a coil of nylon spiral wire loom material and used them to keep things organized.
After it was done I just transferred it all to the piece of plywood and it seemed to work well.

I also cut the side out of a couple short pieces of 1" pvc and laid the wires in there and screwed that to the board too.