Re: Air fuel ratio question
Since the replacement costs of CATs are high, that feds force GM to 8 year smog warranty of them the PCM has a Cat Over Temp (COT) function to protect CAT from high temps.
PCM monitors CAT temps via 02 sensors and depending on elevation the COT trips on between 900-1,000 degrees.
If each exhaust primary runs 250 plus degrees that is easy 1,000 degrees at the collector and easy to trip COT on.
You cannot dial in PE (WOT) AFR without first tuning COT as the whole purpose of COT is when CAT is hot to protect it the COT dumps excess fuel in to cool down temps.
Mike M - 2001 / 2008 Z06s