95 90Q fuel mix woes continue - help with any hypotheses besides vaccum leak?

[Elliott Potter]

On Tue, 18 Sep 2001 10:04:15 -0700 (PDT), Joel Lenorovitz wrote:

> 
>  So I've pretty thoroughly tested my intake system for leaks with my homemade smoke
>  machine system (pictures to come).  I found no significant leaks, but if I pumped
>  enough pressure into the system I would eventually induce a leak around the plenum. 
>  We're talking some pretty decent pressure, though, and something's got to give
>  eventually, right?  I've already performed "Damien's Fix" (replacing the seal) so
>  that juncture should be in pretty good shape.  The bottom line is that there does
>  not seem to be an obvious vaccum leak and my check engine light/driveability
>  problems still exist.
>  
>  The symptoms are:
>  - check engine light coming on
>  - engine hesitating/missing - anywhere from a minor blip to a significant power loss
>  - DTC's of lean fuel mix in both banks
>  - DTC's of new O2 sensors with readings also suggesting a lean fuel mix

I think I missed the beginning of this, but did you check the EGR valve to make
sure it's closing properly?  EGR valve opens when you're on the freeway but
should be closed otherwise, especially under high load conditions.

Just a thought
--
Elliott