1988 90Q dipstick, hunt & peck idle.

[Huw Powell]

> Would you then say that my NG has something wrong?

Not at all.  The main point is that this phenomenon depends on where the 
crankcase ventilation lines enter the intake plumbing.  This can be 
generalized upon on a model by model basis.

If it enters before air mass measurement, the car will run fine without 
the dipstick, filler cap, etc. (except for the oil spray...).  If it 
enters after air measurement, it will screw up the mixture.  How much 
effect it has, again depends on the exact system and tuning.

> If I recall correctly,
> its the exact same engine as in the 88 90q.  Its a 2.3ltr  NA "high
> compression" 10v I5 that uses CIS-e III with a single knock sensor. It dies
> almost instantly if I remove the oil cap and idles terribly if I pull the
> dip stick. Now my old 81 5+5 with  the same engine as the early Coupes with
> totally mechanical CIS...it ran fine with the oil filler cap missing.

Right, I think the cc vent hose on CIS-E3 enters under the rubber boot, 
ie, after measurement.  CIS and CIS-E systems I have seen have the hose 
going to the airbox before the air filter, before measurement.

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/