CIS Guru - Advice Need (strange problem)

[Cory_Langford at bcit.ca (Cory Langford)]

This is a little long, but if you know CIS please read....



Just when I think I have everything worked out again, the mk1 has to be a 
vw and get an attitude :)

I need some suggestions from those old skool CIS gurus out there...

Here is the scoop:

Straight CIS with the following changes:   Turbo'd so fuel added via Audi 
5K press reg.  Replaced the bosch Coil with a Blaster 3.  That is it.  It 
is still straight cis.

Problem:  Car runs fine when first started.  When engine (and engine bay) 
is coolish car runs GREAT.  Nice power, great torque, etc.

When the car starts to warm up (oil temp at about 90 deg. cel.  water temp 
about 1/2 way) car starts to idle high (this morning 2K).

When the car gets to operating temp for a little while (couple minutes 
into 100 deg cel. oil temp and water temp just over 1/2 way on the gauge) 
idle drops to about 1200. 

When the water temp rises a bit (and engine bay temp) - oil temp stays at 
100, water about 3/4 (ie: when driving in traffic) car starts to bog at 
2-2500 again and idle rolls significantly (1000-300 roll).


Here is what I have done (I thought it was a fuel delivery problem at 
first because it started to lean out when warm).

Replaced the fuel pump (it was just starting to buzz, nothing bad but 
figured why not)
Replaced the Pressure reg with a Volvo turbo on I had on the shelf
Replaced all 4 injectors
Replaced the fuel pump check valve
Replaced the fuel filter.

Problem persisted, so replaced the Volvo fuel press reg with one I snagged 
from a good working CIS turbo engine just in case it was an issue.

Problem persists.

This weekend I was going to start looking at electrical (as I think I have 
exhausted the fuel area).  But time did not permit any work on the car.

I thought I would start with a new coil maybe?  Plug wires?  I can't see 
them being an issue. Blaster 3 coil is only about 2 years old, and the 
wires were replaced at the same time with a new bosch set.  The cap, rotor 
and plugs are about 2 months old.



Here is the strange thing I noticed this morning on the way into work:

It did its usual idle rolling, etc.  BUT This morning the free way was 
uncommonly light on traffic so I decided to wind it up.  I gave it a real 
good run.  Oil temp rose slightly (as it does when the turbo heats) to 
about 110 deg. cel.  Water temp dropped drastically, nice cold wind into 
the rad at high speeds. 

What I noticed was as soon as the water temp went down to about 1/3-1/4 
the car kicked back into the "good" mode.  Idle smoothed out, power 
restored at 2K, etc.  Oil temp was still up, but engine bay temp was way 
down.


Now from personal experience, rolling idle when everything else has been 
checked (timing, mixture, base idle, etc) usually means a vac. leak in a 
CIS car. 

So now I am starting to think I should be looking for a vac leak that 
presents itself when the engine bay heats up, and seals itself when the 
bay cools.  A great thing to search for :)



Any Ideas?  I am running low on things to change...


Cory Langford
'86 Roc turbo, 
'78 Roc turbo - Daily driver project,
'65 Ghia Coupe
95 Eurovan, etc, etc... :)