GM.AFR problems?? Commanded doesn't match B3618

[maudyZ28]

Hi All,

well looking through my tune, and although the wide band AFR are good, they are not a perfect match everywhere.

checking back on my log i see the commmanded AFR is NOT exactly the same as the B3618 table ?? There should be NO other modifiers in affect when engine is at temp should there ??

[WeathermanShawn]

Maudy, I did not want to rain on your OLSD parade, but unless you have a really radical cam or some need to run other than stoich for the majority of your Tune..why not consider at least CLSD.

Temperature can affect an OLSD Tune, otherwise you would not have a COS with a A0014 Temperature modifier.

It just a thought. If your mainly stock and running on the street..just something to consider. Trims can be your friend..

P.S. this is not to start a OLSD vs CLSD war..just some perspective having tried every possible Tune you can run on the street...

[mr.prick]

Here's why I don't use the {GM.AFR} pid.
Commanded AFR ≠ {B3601}

In your log i see you're using the standard pids for AFR & BEN.
I suggest swapping them for calc_pids based off {B3601}

"({GM.EQIVRATIO}/{B3601})" = Commanded AFR
"({B3601}/{GM.EQIVRATIO})" = Commanded AFR

"({GM.EQIVRATIO}*{EXT.WO2LAM1})" = BEN
"({GM.EQIVRATIO}/{EXT.WO2EQR1})" =BEN

[maudyZ28]

thanks guys, mr prick, i'll try the PIDs I did read something like that before but then when i did a seach I could no longer find it, thanks It may help to get the right BEN for auto VE lol

shawn, hahaha, 'rain' on my parade. NIce pun
I know what you mean, and I do plan to run CLSd or CLMAF even again. But for now I wanted to be fluent with every part of the tune and use open loop to find a suitable switch point to set the O2 switch points. Then do a full Auto MAF cal in same manor. Then i'll add a couple of 2% extra to bottom end of MAF or VE just to make sure the CL trims are -ve such that it make the bottom end run at stociometric and wont add fuel at WOT and it will exclusivly read what I have dialed in. or thats my theory.

I did notice in stock tune form it would run leaner the commanded at WOT when trims were reset but stociometric would be ok, but STFT were +ve which passed to LTFT and they were +10% then which added more at WOT which made fueling too rich. Once i get MAf and VE sorted I think trims will be +/- 1-2% and so fueling will match, provided I use the correct PIDs