Stalled when oil filler cap off.

[Nate Stuart]

Douglas Frank wrote:

>I'm a little confused.  OK, more than a little.
>
>The oil filler communicates with the top of the head, not the intake.
>What's to suck vacuum there?
>

There are inteconnections between the intake and the crankcase
ventilation system to scavenge the fumes that occur in the crankcase
with a running engine. The vacuum source on the turbo motors happens to
occur post metered air, and will generally cause the car to stall when
the oil cap (also open to the crankcase venting) is removed, by letting
in a rather large amount of unmetered air in(and therefore much less
needed fuel). It's not so much that there is a *large* vacuum there (all
the air is drawn from pre throttle body), but just enough from the
intake stream to pull the gasses out of the crankcase.

I dunno if that cleared anything up for yah!? Hope so!
-Nate
'89 90tq
www.newtsplace.com/90tq