Question on running pure maf OL and CL and differences

[07cobaltsupercharged]

I wanted to see difference between OL and CL MAF afr error% with VE table completely disabled. OLFA table is also all 1's at operating temps for this test as well.

After a long drive not going into PE in OL I have maf afr error to within 0-1% all the way across all cells. I then went to CL and went on same drive, same conditions and maf afr error was now +4-6 % yet stft's are showing -1 to -3's everywhere in histogram and 0-1% in MAF stft error %.

If my VE table is disabled what is causing the difference in afr error % between OL and CL? Are the narrow bands in CL not accurate with my stoich set to 14.27 for the 7% ethanol in my fuel so in OL its more accurate? And if so how to correct for this while in CL?

I run pure maf CL with no VE table referenced so just trying to figure out whats causing the difference and which is more correct for MAF error % the stft's in CL or the WB error % when in OL.

[5_Liter_Eater]

This is tough becuase you don't know which sensor to trust. I would say that more than likely the meth skewing the stoich is throwing of the narrow bands. Just because you set stoich differently in the tune doesn't mean the NB's will switch differently. You can change the switchpoints until they match. I detailed a procedure on how to do that although it 's in the 4th gen forum it applied more to 3rd gens.

http://www.hptuners.com/forum/showthread.php?t=11333

Basically you log the NB mV when the AFR logged on the WB is close to 14.7 (or whatever you want stoich to be) while in closed loop and plot it against the airflow mode table to come up with new switchpoints.

HTH

[07cobaltsupercharged]

Thanks for the link...
I can of course just run in OL as well and not worry about the NB's at all but hot/warm restarts are always a bitch because afr's drift way lean and hard to control so far in adjustments to tables for it. Today I just put it back in CL instead of the hassle of the lean startups cause it was just taking too long to get afr's in line idling/lower rpms.

I think im just gonna leave it for now and do CL.