Looking the attached cutoff page from the original gmpp tune in the supplied E67 ecu on an 2012 ls376-480 it would appear that all rev limits are disabled. Am I missing something? This motor is in an endurance road race car which races in 3 to 25hr races and definitely need a rev limit to guard against late upshifts and excess heel and toe blips on downshifts. Logged data has shown overrevs to 7500 that were not due to early downshifts.
Which is most effective and causes least disruption after an overrev ie fuel, spark or ect cutoff. I would think ect would take too long to react.
Logged wideband 02 data has shown on throttle afr's in low 13's until about 15 minutes of racing and abruptly shifts to low 11's or richer and stays there. There appears to be no correlation to ECT or airflow although logged 'calculated oil temp' from the ecu seems to cross about 255F and rises every time the enrichment happens.
Looking at the tables I noticed a COT funtction that is apparently based on a calculated Cat temperature that could be causing this enrichment although the car has no actual cats. I'm guessing that the oil temp and cat temp may be calculated from the same parameters.
I'm considering disabling the COT function for a practice or sprint race session to see if this is causing the AFR shift. Could also possibly log the cat temp if available.
Also found out that the fan control relay wouldn't turn off in the shop but works properly if the vss shows the car is moving.
Reply With Quote