Important note re VAG COP units

[16vboost]

The battery is in the trunk, but grounded to the chassis. The positive terminal runs up to the stud on the starter (like OEM) and the factory wiring harness takes +12v from the starter stud to the fuse box. I tried to power MS as if it were the old factory CIS-E oxygen sensor control unit which isn't quite like the current wiring diagrams. As a result, there may be some ground loops.

I almost want to remove the capacitors from my harness and investigate further. But no. If it ain't broke . . .

Thanks elaw for starting this thread and the useful information it contains. Now if we can just get those manuals updated.

-Alex

[savagerocco]

On my audi 4k I kind of remember having issues until I grounded the coils to the chassis away from common ms grounds. But that has been several years ago and my memory isn't as good as it used to be.

[yzn]

To add an extra note, a week ago i had problem with engine not firing it turned around that the ground for the coils signal on the engine block was bad so i moved it to where the coils power are grounded so now i had both ring terminals grounded to the same place but then i had a knocking problem every time the engine hit the boost, today i moved the the signal ground to a chassis ground and the knocking went away. I'm running 115r COP with the old manual 5v pull up circuit.

[weeblebiker]

both pin 2 and pin 4 ground should be separate and separate from the ms ground by a few inches. even a hall grounds will feed noise into the ms ground if bolted on or near the ms ground.