Help...can't find value.

[SSpdDmon]

Before I try to fix the tranny issue I posted about earlier, I've been plagued by a fueling problem. I'm just about to wrap up a decent VE tune, but I can't find something. In my logs, GM.AFR shows the commanded AFR. After tuning the VE with the open loop table at 12.5:1, I returned the open loop table to stock. I set the P/E vs rpm table to roughly 12.7. However, in comparing the commanded AFR to my VSS (MPH), I'm finding the PCM is commanding a 11.7 AFR in 3rd gear @ WOT. 1st and 2nd follow my tune. But, 3rd is off in lala-land and I can't find the freakin' table to fix this. Anyone have any clue where there would be something adjusting the commanded AFR aside from the open loop and p/e vs. rpm tables? I've checked those and the p/e vs. ect along with the p/e vs. iat. Abuse mode has been disabled. Someone please help!

[Black02SS]

Is there anyway you could send or host your log and tune?

[SinisterSS]

One thought - is catalytic converter protection enabled? If so, after 1st and 2nd gear, the computer might be thinking the converters are hot and dumping extra fuel to cool them off.

[Black02SS]

I was thinking the same thing.

[SSpdDmon]

I can host the tune/log later tonight if it's necessary. In the mean time, I will try disabling converter protection and see if it takes care of the problem on the way home. Just out of curiosity, is disabling this going to harm the cats? I don't drive WOT all the time. So, I would assume if it's not normally entering cat protection, for the most part it would be ok. What do yall think?

[SinisterSS]

Converter protection is there for a reason. If one runs on a road course or other high speed sustained events, a cooked cat is possible with it turned off.

Also depends on how lean you are running at upper rpms, etc. If you are running 12.7 in the upper rpms like you mentioned, probably could disable it safely. Another little safety step would be to richen your fuel mixture as you approach your rev limiter.

[SSpdDmon]

Converter protection is there for a reason. If one runs on a road course or other high speed sustained events, a cooked cat is possible with it turned off.

Also depends on how lean you are running at upper rpms, etc. If you are running 12.7 in the upper rpms like you mentioned, probably could disable it safely. Another little safety step would be to richen your fuel mixture as you approach your rev limiter.

Aside from the occasional trip to the dragstrip, I don't really stay in the upper RPM's. In MI, cruising on the highway puts me around 2400~2500 RPM's. I don't think those kinds of RPM's for 10-100 minutes would be enough to cause that to kick in, do you?

[SinisterSS]

Nope.

[Bruce Melton]

I had a leanish ~13 dyno tune programmed in and after the first run the car went so rich you could not survive in the dyno room. (10.6-11.5 one run). It was the cat protection.

[SSpdDmon]

That took care of it. You guys rock! Thanks!