How 'bad' is it to disable COT temporarily for VE/MAF tuning on cars with cats still installed ? Will it kill them before I can get it tuned ?

I'm having problems with the commanded AFR intermittently jumping rich (14.6->~13.3) while logging for VE and it's whacking my average logged A/F error %... I still have COT enabled because the cats are in there but it looks like I can't get an accurate log without disabling it (at least I'm hoping/suspecting that's what's causing the wandering AFR)...

Thoughts ?

Thanks !
Rob (Bad30th)

 

Mine and quite a few guys I know run permanently disabled. Maybe partly because our widebands and tuning gear is also permanently installed, but unless you are road racing, or extended periods at high load and/or run a little lean you should be ok. Around town you will definately be ok.

 

do you have a 2 bar OS? Or are you trying to dial in your VE with just a 1 bar even with your blower? What are you commanding in the OFLA table?

 

I have the 2bar HPT upgrade but I still have the 1bar MAP sensor installed...

I'm mostly tuning for drivability and cruise though, 2000-3200 RPMs, low MAP. That's where the part throttle stumbling is happening. No real need for the 2bar yet to get that stuff straightened out...

My original tune has pretty bad surging at cruise (you know the kind of feeling when the MAF table isn't right like it's stumbling ?). I am going to take another stab at the VE table starting today, but I think I need to get the wandering AFR issue resolved to get good logging for VE.

...so it won't hurt to turn COT off for VE logging for a few days (hopefully) ?

Rob (Bad30th)