Bedfordman

I had very poor running on my '91 S4, traced it to a fractured Earth Strap, the short one that is on the throttle mechanism side of the engine and connects the block to the coil mount bracket.
Looking at the Porsche Parts Diagram I saw that there should be one on the side of the engine close by the jump post too. Not on my car, and no sign there had ever been one there.
There is a threaded hole on the engine lift bracket so used that and connected the other end to the coil bracket. -- she does seem to run better with it.
Are these the 'correct' fixing points? seems strange to directly earth the 2 coil brackets, but maybe just convenient.

Peter

Landseer

I thought they were added to the 32v cars for suppressing radio noise / interference.

There's a technical bulletin in the Morehouse CD set that describes this.

davek9

Yep that is my understanding too, as stated they do not affect the running of the engine ( I ran a 928 for years w/o them), unless your engine ground strap has issues too, its under the car on the right side of the engine to the chassis.
You most likely disturbed (and fixed the real issue

Dave K

928NOOBIE

I refreshed both cables when I replaced the coils....so can't say for sure what made the difference but it def. ran better. Every time I refresh grounds I gain a little bit; you certainly didn't do any harm by cleaning those up.

To above the engine ground strap underneath is really important; if it hasn't been addressed pick up a new one; they are available from the 928 parts gurus (OEM).