The ABF loom will need some tweaks to plug straight into a MK2 and have everything working, to start with bin all the MK3 lighting loom and keep the MK2 one in there, the lighting and engine looms are seperate so thats no problem. Then on the engine loom some things like the radiator fan, MFA & coil plugs differ slightly.
Since I'm quite anal about these things I wanted it to be as close to how VW would have done it with as few cut wires as possible. It takes more effort this way, but the end result is worth it!
What I did was to lay out a CE2 16v loom (8v loom is just as good, just more bits to remove) next to ABF loom & unwrapped it all. Tip: every foot or so put a single bit of tape round it to keep it roughly in the right shape!
Then I binned all the ABF bits that wern't for the engine, and all the bits from the MK2 loom that WERE for the engine. Then check out the fusebox plugs you have left, you'll end up with 2 of some of them, compare these and see how many wires are in each. Choose the one with the fewest pins in and swap all the wires to the other one!
Also make sure you keep the MK2 firewall rubber grommet so you know it fits, I cantr remember if the ABF grommet was the right size? Poping pins out of fusebox plugs is fiddly, ideally you want a proper tool but you can do it with a thin watchmaker screwdriver.
You may be left with a couple wires that need to go in the same socket, in this case what I did was to trim the insulation back on the wires in the plug you'll keep (dont cut the wire, just trim the insulation to expose the wire) then wrap the end of the other wire round the 1st wire, solder and cover with electrical tape.
Finally you are left with an awesome MK2 ABF loom, but its all unwrapped and looks like arse! What you need is some of this stuff:
Its called
Twistwrap sleeving, its awesome.
However the largest size they do isnt quite wide enough for engine looms, you could split it into 2 smaller looms, or do what I did and put a twist to it, I turned it in my hands till it covered the wires, then taped up the loose ends with loom tape. I really took my time over this part and the end result was very nice, for all the bits where the loom splits off I tried to get the loom wrap inside the main body of the harness, and taped round the join. God knows why I bothered though as it wasn't even my car
It all sounds very complicated I know, its easier to actually do it than it is to expain over t' internet
