Vacuum Line Sizes- Coupe GT

Huw Powell audi at humanspeakers.com
Mon Apr 10 22:14:27 EDT 2006


> Bear with me for a moment but my '86 CGT is new to me
> and so is CIS.

It can't hurt to look this stuff over then:

http://www.humanspeakers.com/audi/timing2.htm

http://www.humanspeakers.com/audi/tuning-cise.htm

> Car was idling bad at start up, then stalling. Once
> started and warm, it will idle ok but hesitate under
> load to the point that it sounds like its running on 3
> cylinders. When I get on the gas and it's idling to
> bring the rpms up, I hear this popping sound. This
> problem happened all of a sudden, it's not like it
> started doing this intermittanly or anything. I parked
> it Sunday night, and Monday morning it was acting up.
> 
> It was wet that day and I felt arcing through the
> wires so I replaced cap, rotor, wires and plugs. No
> difference. I replaced the two coolant temp sensors
> and cleaned the ISV. Was running then at about 97%
> perfect, checked for vacuum leaks but didn't notice
> any and thought I was in the clear. No garage at home
> so was working at a friend's place, on the way home it
> went back to the same song and dance..no power, having
> to rev high between shifts to keep from bogging down,
> occasional pop.
> 
> I've decided the next step is to replace all the
> vacuum lines and the O2 sensor to rule those out...

I would not recommend randomly replacing parts - you should try to 
diagnose the problem first.  Although, doing something like the vac. 
lines can be good, since they are very old.  I don't remember the sizes, 
but a decent import parts place might be familiar enough.

You also have a lot of molded rubber bits to check, there's one with 
four ports by the intake manifold that is prone to cracking (underneath, 
usually) with age and wear.

You *definitely* should check the CIS fuse - it's the one in the side 
strip in the fusebox, and often gets removed by people thinking it is a 
"spare."

> I've also read that the valve cover gasket can be
> another vacuum leak...is that common?

More like an oil leak, I wouldn't worry about it here.

> PS I also noticed that the oil pressure gauge is
> pegged at 5bar even when hot and not under load. It
> didn't do that until after I cleaned the ISV and
> replaced the sensors...coincidence? Causes?

Shorted or disconnected wire to the sender (on the port side of the 
block) perhaps?

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/


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