Audi S2 Coupe Project-Wiring and Ancillaries

Well I have finally ventured into the wiring of this thing. I have been spending many hours with the forums and the wiring diagrams trying to decide the best way to go about putting in the 3B engine harness. Looking scary inside right now. Yanking on big bundles of wires around the fuse box does not instill confidence in the ‘untouched’ electrical connections…

The primary internal debate involves what is the best part of the harness to leave in from the 7A and what should be removed from the 3B harness. I want to remove any unnecessary/redundant wiring. For you guys that have done the swap, what was left coming into the bay from the original harness (i.e. alternator, brake fluid, etc.)? Are there any other connectors that need to make it to the fuse panel other than the black ‘B’ connector, the ‘O’ single, the ‘87a’ single, and maybe an L30 or two? If I replace the 7A ‘B’ connector, I think I need the starter output added to the 3B ‘B’ connector, circuit 50, I think.

You may think it is almost done from this pic, but I know that to be untrue…It is kind of inspiring, though…

I also got the RS2 fan shroud installed with the 3B fan. I need to look into making this work right without melting anything. Suggestions for an OEM approach? I know it is out there, but I’m growing lazy.

I have also been working on getting things laid out in the bay. Harness connector bracket mods, afterrun pump bracket, cooling and hydraulic lines, etc. That reminds me; I had to bend the line going from the pump to the bomb to clear in intake manifold. Then, because of that bend, the line from the pump to the rack also needed to be bent. Unfortunately, I broke the solder joint on this trying to finish the bend. So I need to fix that now. Anyone know what was used here? It seems higher temp than the typical electrical solder. Maybe some silver solder or something like that?

Then for some reason the first starter that I put back in did not want to engage the flywheel and crank the motor over. I had bad thoughts of me doing something wrong with the assembly. It was weird because it was obviously engaging the solenoid and spinning the starter motor; it just wasn’t turning the engine. It was definitely in all the way, too. So, luckily, I have a second one around and installed that next. Yes! It works! I actually powered up the electrical portion of the car and turned over the engine a few times. No plugs in right now and I’ll see how I can build oil pressure coming up here soon. I also pulled off the ABY crossmember and intercooler to clean them up and paint them.

In the meantime, I’ve got some work to do to prepare for a potentially running engine. I also need to find a set of injectors to use.
I will be making up a pressure pipe out of 2.5” AL because the 3B one won’t line up with the ABY parts very well.

The fuel lines fittings in the bay on the CQ are different sizes, unlike the 3B lines that I’m using. Does anyone know the sizes here and if I can just use an adapter? It looks like the 3B lines should work otherwise.
I’m using the ignition module from the CQ as it packages better than the 3B one I have. I have seen other 3B units that are the same style as the CQ one, so I think it should be OK. If not, I can go back to the big canister one, but hopefully won’t need to.

The 034 AAN MAF to turbo hose also is not going to work with the ABY airbox. I’ll be using the stock one for now, but hope to find a black silicone version to match everything else. I can deal with a little mismatch for now. Much larger issues at hand.

The metal water line under the water manifold needs to be modified as neither the 7A nor 3B will work untouched. The 7A would need the afterrun pump nipple put in; besides that it is rusted through in spots. So I’ll use the 3B one as it just needs shortened with an elbow at the end to head toward the heater core.

There are a lot of little details to take care of, so I am trying to stay focused and finish tasks without constantly jumping around; at the same time, I sort of need to so that I can get some longer lead issues tackled in parallel. I would like to get things wired up for functionality this week. I will clean it up once I know where things will need to end up…