May have solved my SC dilema
 

I recently posted about problems I am having with my 82 SC.

http://forums.pelicanparts.com/porsche-911-technical-forum/216084-help-what-have-i-done-my-sc.html

I pulled out the CIS pressure tester that hasn't seen the light of day since I rid myself of my '78 928 and checked pressures.

Cold control pressure: 65 psi ! - car not running

System pressure: 75 psi

Rest pressure: 22 psi after 10 minutes

Never did fire it up to check warm control pressure after i saw the cold pressure.

I guess this would explain my backfiring, refusal to rev, exhaust smell, and poor idle??

Why would this fail suddenly?

Kirk

Kirk,

The same thing happened to me a couple of years ago. The engine ran great, and then one day, the backfiring, poor warmup idle, etc. I went through checking ignition, mixture, vac leaks, etc. I then remembered my old VWs for the Compleat Idiot book I had left over from my late 70s Scirocco days, which, along w/ a fax to Bruce Anderson got me onto the WUR and the knocking the pin method. Since this was before I knew of this BB and fuel pressure gauges, I was able to get the thing to work better by some judicious pin knocking, but never quite right. I have since replaced the WUR w/ one from an Audi 5000, which I knocked a little, which works better than the one I had ever did.

I think this shows that these things can actually take being out of spec by quite a wide margin and still perform well, especially if the cold start temps are not too low. And then one day, it is finally too far gone and must be recalibrated.

Alternatively, another part of the WUR could fail suddenly which would then cause the poor run condition. In this instance, knocking the pim won't help, and the WUR has to be replaced, or the failed component replaced from another unit.

there is a series of small screens in the WUR that acts as a filter. If you pull these screens out and clean them one by one it might fix your cold pressures. Do this before messing with knocking the pin. On my car I did not have to knock the pin, just cleaned all the internal parts. The Wur is not that complicated inside.

You can get the screens out with a dental pick, and not have to open anything up. Just remove the fittings from the top of the wur. the screen is under there.

good luck