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

[Mark Strangways]

Renew the O2 sensor...
Check Fuel pressure against spec at idle. Too little vacuum could increase 
FP thereby rich mixture.

Pressure test intake system.
Check MAF against known good, but usually a bad MAF makes itself known.
Check what the actual duty cycle of the injectors are, vs..s known value 
from someone with the same capacity injectors.

All in all, I bet air leak in a nice hidden location, maybe even at the ecu 
or the line to the ecu.

Mark
----- Original Message ----- 
From: "Sandy Sligh" <sdslig at yahoo.com>
To: <s-car-list at audifans.com>
Sent: Sunday, May 29, 2005 9:59 AM
Subject: [s-cars] emissions results and code 2231 = air leak?


> 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"
>
>
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