Using the Desired/Actual AFR's to tune the MAF cal

[mituc]

After doing my MAF cal and ending up with an almost perfect CL calibration I started looking into the OL part of it trying to make it even more perfect after the initial tweaking. First I scaled up the values based on the CL multiplication factor and then used the Desired and Actual AFR ratio's to compare what's commanded and what's hit.

After finishing that up and having an OL MAF cal with pretty much identical Desired and Actual AFR's I noticed that sometimes I'm a bit too far from the targets (5%, sometimes even 9%). So what is the right approach for the OL part of the MAF cal? Using the Desired and Actual values or use the Actual values and compare them against the target AFR's?

[JUT]

When I first purchased VT, Steve told me to log Desired and Actual Equivelance Ratios and use those values to complete my WOT MAF cal. I find that in my logs the Desired Equivelance ratio is the same as what is targetted in my Open Loop WOT AFR Target tables anyhow.

[mituc]

I know that, but in my case the desired and target ratios are slightly different so that's why I'm asking.

[JUT]

Do you find that your desired afr's in the logs are the same as those targetted in the Open Loop Part Throttle Target table?

[mituc]

Nope, as stated above the desired afr and the radio's in the OL target tables are slightly different.
However, the desired and actual afr's match.

Basically at this point I'm trying to understand if I did something wrong when I did my MAF cal, or since it was done mainly during winter if the winter fuel had any effect on that, or if in the meanwhile something else happened with the car such as developing an intake or exhaust leak (I tested the intake with a beach ball cut in half and a bicycle pump, no air was coming off from anywhere).



Here's a log, you'll see AFR's there in hid/high 10's around 4k rpm's while in that area I'm targeting 11.7 or so.

[joey]

Could be fuel related issues. Mine also drifts from time to time. As Steve said 5% deviation is acceptable and considered as calibrated. I hate doing OL maf cal as it takes quite some time. I wish it was as easy as CL calibration haha

I had bad AFR(first O2 sensor) and a bad 2nd O2 sensor. I replaced both and now my cab seems to show my desired afr correct in the logs at wot. Before it never did that. Now i see the results of my calibration in OL

[mrQQ]

you should use PID values.