[s-cars] emissions results and code 2231 = air leak?

[Sandy Sligh]

Collective Audi Brainpower! Unite! 

I've located my last three emissions reports. Take a
gander.

March 2003:

HCppm IDLE limit: 220
HCppm IDLE test: 447 FAIL

HCppm @2500rpm limit: 220
HCppm @2500rpm test: 151 

CO% IDLE limit: 1.2%
CO% IDLE test: .93%

CO% @2500rpm limit: 1.2%
CO% @2500rpm test: 1.15%

This is the first emissions test after i bought the
car. The ultimate solution involved a new 4.0bar FPR
and a new Stromung center section (cat included). Here
is the result. Note, the limits changed during that
time:


April 2003:

HCppm IDLE limit: 120
HCppm IDLE test: 48 

HCppm @2500rpm limit: 120
HCppm @2500rpm test: 68 

CO% IDLE limit: 1.0%
CO% IDLE test: .04%

CO% @2500rpm limit: 1.0%
CO% @2500rpm test: .14%

Passed with FLYING colors. Obviously, looking back on
these results, the new cat was taking up the slack of
an underlying problem. Here are my current results:

May 2005

HCppm IDLE limit: 120
HCppm IDLE test: 322 FAIL 

HCppm @2500rpm limit: 120
HCppm @2500rpm test: 309 FAIL

CO% IDLE limit: 1.0%
CO% IDLE test: .77%

CO% @2500rpm limit: 1.0%
CO% @2500rpm test: .74%

HC is high again like back in 03/2003 and the CO
percentage is creeping back up to where it was in
03/2003.

With the high HC AND relatively high CO%, I can't
figure out any other reason besides an overly rich
mixture. If I assume that Bob Pastore's software isnt
purposely running the engine rich at idle (no reason
to), the only thing that i can imagine that would
cause a rich mixture would be:

A leaky fuel injector? A airleak after the MAF?

What else?

In addition, code 2231 is present, indicating one of
these as the possible cause: Idle Speed Control, Idle
speed adaptation limit exceeded, Sticky ISV, air leak

Is it time to pressure test the intake?


Thanks again for any advice in advance

Sandy
1993 S4 CAN
RS2: Comp Turbo, MAF, EM, FIs
26lbs Pastore software
Stratmosphere bypass
Eibach/Bilstein
996tt calipers over 993tt rotors
Stromung 3"