Vanners,

For the second time the tach in my 87 syncro westfakia converted to TDI went crazy for a while. Bounced up and down and all over then after a few minutes went back to regular. It a diesel dash pod with a diesel tach.

It was very hot yesterday but the first time it happened it wasn't hot so….?

I have a tech tool hooked up  and it shows a steady tach reading. but it's kind of disconcerting.watching the dash board tach go nuts.

Any ideas on what goes wrong and how to fix it.

Mike