Commaned A/F occasionally goes very lean at idle (E38 cammed G8)

[Patrick G]

I occasionally fight a strange issue with cammed E38 cars commanding a very lean A/F ratio (like 16:1) in closed loop for short times during idle. This makes the idle very rough when this happens.

I figured it was the EVAP purge going on, but when I massage the contributing tables, it still does it. What am I missing?

I've set B1521 to all 1s. This should keep the A/F ratio from changing.
I've set B0190 to max temperature to keep purge from happening.
I've zeroed out B0192.

Here's the tune:David Moore 2009 Pontiac G8 GT PG ECM.tun

[joecar]

Hi Patrick,

Do you have a log file...?

[TJWells]

Just a guess, but try disabling {C1701} and {C1709}.
However this would be a test only, as you will never pass an emissions test that way.

[joecar]

TJW has a good point, it might be the rear O2 and/or catalyst tests activating.

[TJWells]

Catalyst efficiency test was my best bet!