Basic setting of control pressure regulator on CIS-E3

Eyvind E. Spangen 200q20v at
Tue Sep 18 13:02:02 PDT 2007

I have an '89 100Q with engine code NF. The previous owner had messed with
the basic setting of the CPR (the 2 mm allen on the back of the CPR),
probably the mixture screw between the metering head and the air boot too,
and the car had a major vacuum leak in one of the ISV hoses. I replaced the
ripped hose, but something is not right. 
I have a car that runs great when driving, but if I press the clutch, it
will drop to about 500 rpm, back up to 1300, down to 600, back to 1100 and
then between 600 and 800. It will never settle completely. I feel totally in
the blind adjusting this, so I don't want to end up with a too lean or too
rich mixture. What should I do? Just find a junkyard with a car like this
and replace the complete fuel distributor with an un-tampered unit? I
suspect that it'll be very hard to adjust both the CPR adjustment and the
idle mixture screw right and not end up with one too rich and compensate
with leaning the other one.. As for now, the mileage seems a little bit low,
but I'm not really sure.

I have checked the system for vacuum leaks and replaced one of the ISV
hoses, but I can't find any more. Maybe a small vacuum leak, like injector
seals or something can make the idle act up, while the car feels OK when

E. Spangen

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