Forty-six and 2

I am swapping a VW motor into my car, and am getting rid of the engine harness and related parts. I plan to upgrade the light harness from under the dash and forward. It would be nice to replace the outdated fuse/relay block with something up to today's standards. I will be using an standalone engine management system, powered by it's own relays.

I know I can't be the first person with these thought. Any write up or first hand knowledge on the subject? Any problems with making this happen?

odonnell

It's a ton of work. Closest thing I've done is made a custom board for managing the powered components of the engine bay.

- replaces DME relay functionality
- has dedicated fuse block
- runs coils from dedicated relay instead of thru ignition switch like stock
- place to mount ECU

It was hours and hours of work, I can't imagine how much time and effort it would be to rewire everything.




skip to 4:30

Forty-six and 2

Looks good!

I will be using Ms2 with the relay board and it's own engine harnes. That will simplify everything down to only needing to run the lights and the handful of other accessories. The stock fuse block would end up getting completely stripped down to the bare essentials. At that point a universal block should be a fairly simple install, using the new blocks harness to connect the car's harness. This would give me the necessary wires to make a new front end light harness.

Wiring is tedious, but nothing to fear, if done properly. Your setup looks nice and clean. It's very rewarding when done well. I have enough harness work to do, it just might make the most sense to remove the factory, potentially hazardous, fuse/relay system.

FRporscheman

Which VW engine? Do you have a thread?

I have a VR6 in my garage, I hoping I'll have time next winter to put it into my 951 track car.

Forty-six and 2

It's an 2.2l aba with a 16v head on it.

I don't think the vr6 will fit, due to the oil pump. It is on the pulley end of the oil pan. That is where the pan has to be modified to fit over the crossmember. A custom tubular crossmember might work.

I haven't updated it since I started on the swap 2 weeks ago. The motor is in the car, and I am building the driver's side engine mount right now.

https://rennlist.com/forums/924-931-...low-build.html

I update my ig page regularly if you are on there. @46_2

Tiger03447

might be easier to come up with a custom pan for the VR6.

V2Rocket

sausage, can you detail how you wired those 2 relays to replace the DME relay?

i know its just 2 in one but just to simplify what hooks to what.

odonnell

It's really just one main relay, with the fuel pump relay acting as one of the powered devices off the fuse panel.

- when you put ignition switch in run (or crank) position, 12v from the ignition switch activates main relay. There is a ground provided by the ground point on the right side of the glove box. These are the 85/86 terminals.

- there's a 10 AWG wire coming right from the battery to terminal 30, and then terminal 87 goes to the main lug on a AutoZone fuse panel. (for those who are reading and don't know what the terminal numbers mean: the ignition switch "completes the circuit" between the battery and the fuse panel).

- the devices plugged into the fuse panel get 12v, ground is provided wherever, per-device basis.

- the fuel pump relay gets 12v to the activation side as well as to the power side. there's probably some relay lingo I'm missing but you get what I mean.

- in my case, MicroSquirt provides a ground to the activation side of the fuel pump relay. Since it already has 12v, this allows the fuel pump to run whenever MS decides to provide the ground.


For replacing the DME relay you'll need to simply merge this config with the factory harness. The DME relay provides 12v to the DME via two pins - these will come from your fuse panel (or more generically, the main relay). Then you'll take the DME pin that provides a ground to the fuel pump stage of the DME relay and use it to ground the new dedicated fuel pump relay, if that makes any sense.

Really can't recommend this setup enough. I have zero flaws, although I can't speak for long term use because it's only been a few weeks. The relays are basic 30/40A and are a dime a dozen. There's rubber under my wood base to provide vibration isolation to some degree.

Trying not to write a novel here, but you're best off working with the connections at the 9-pin connector by the brake booster - it's where the DME harness interfaces with the fuse panel. A guy on 924board made an excellent diagram for it, it cover the bases for this job.