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I5 without oil filler cap

In message <9702191857.AA43648@fluhr.austin.ibm.com> ejfluhr@austin.ibm.com (Fluhr) writes:

> Ahh, but from experience, all these areas fill with hardened oil residue,
> restricting or clogging many of the passageways (expecially the rubber
> collector underneath the ISV, and the crank ventilation tube).  So, I
> theorize that older engines with these restrictions may not sufficiently
> flow enough air to cause the engine to stall or stumble, and may be
> compensated for by the computer.  I guess the best way to determine this
> is to measure the pressure actuator current as you pull the oil filler
> cap off.  If the current increases, the ECU is richening the mixture to
> compensate for the vacuum leak.  Sound about right?

No.  What happens is that, over engine life, leaks develop gradually.  Each 
time the CO value is reset, it's set a little richer to compensate for the 
increasing leaks.  Finally you reach the point where there's so much air coming 
in via the breathers that taking off the oil filler cap makes damn all 
On most of these engines (the ones that are _supposed_ to stop) resetting the 
CO values with the breathers off and plugged will result in an engine that 
won't run when the breathers are re-attached.

 Phil Payne
 Committee Member, UK Audi [ur-]quattro Owners Club