[E-30 325]

Recently did a 16v conversion in my 81 scirocco. All maintinance parts are new and have been looked over to make sure they are not causing my issue. Has a terrible miss on WOT, but at idle it purrs nicely. This issue will go away rarely like this weekend I picked the car up and it was incredibly quick with no misfires. Its a big downer, Ive checked timing and mixtures. Could it possibly be a bad ignition coil or a ignition control module? Sometimes sitting at idle the rpm gauge will go into a frenzy and then work properly again, I bring this up becuase the tach gets its signal from the coil.

any ideas will be greaty appreciated!

 

[tehmonkay]

So the mixture has been checked with a wideband gauge at WOT? Is it maybe running lean? Does the engine misfire when the tach goes crazy? If it doesn't that's probably not the issue.

 

[Rocco_julie]

The tach will jump due to bad grounds.
I ran grounds from a stud on the back of the engine to the electrical system and the chassis.

 

[[email protected]]

How about a weak fuel pump? If the car couldn't accumulate enough pressure at the fuel head it would cause starvation at higher RPMs.

 

[ps2375]

What fuel and spark control?

 

[fredybender]

Check your voltage regulator on the alt...
Happened to me last year on a Mk3 16V swap
simple things first...