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RE: 86 CGT rough at low rpm
Simon, Rick and the list,
My ISV sticks sometimes (despite best efforts to clean) causing my car to not idle at all when cold, a good squirt of wd40 may do the trick for a while.
Iain
-----Original Message-----
From: Simon Allcorn [mailto:simon.allcorn@cartesian.co.uk]
Sent: 15 December 1999 11:32
To: 'quattro@audifans.com'; 'RickE@triadperform.com'
Subject: RE: 86 CGT rough at low rpm
Sounds very similar to the problem I am currently having.
First off there a pipe from the rocker cover that goes to just above the
air filter / just below the metering unit - mine was softer than butter
and had several holes in it and was 'crazy paving' cracked all the way
down.
Second off I suspect that my auxiliary air valve (also called the ISV (I
think - anyone care to correct ?) is stuck shut. I think this is then
causing the engine to not have enough air so it gets extra air from the
next easiest source - the pipe that was broken (btw there was also quite a
bit of oil sucked in via this pipe). I should be checking the ISV this
weekend so I'll keep the list posted.
Anyway if I'm correct about the ISV (I suspected for a long time the cold
start valve (extra fuel valve) but I've connected the electrical supply for
it to a light in the cabin and it's activity doesn't fix the symptoms) then
if you get your car warm (warm as in the temp. gauge has been stable , i.e
about 1/2 way for AT LEAST 10 minutes of driving) then the engine should
show no hesitation at all.
Also you can check the ISV easily (There's a pipe about 1/3 - 1/4 inch in
dia from the inlet manifold (next to the supply for the brake booster -
!turbo uk only I think) which goes into the ISV and then the pipe comes out
and connect the upstream side of the throttle butter flies (don't you just
love having 2!!). Anyway start the car when it's cold and pinch this pipe
hard and the engine should stumble - if it doesn't then the ISV could be
stuck shut. Then when the car is hot do the same thing but this time there
should be no change in the engine tick over - if there is then the ISV
could be stuck open.
Also make sure there are no vacuum leaks in any pipes ! (arse I know but so
is no power at 2k!)
hope this helps.
Simon
87 coupe Quattro, no power at 2k when cold