VersaTune User Forum

Hi all,
getting into tuning this platform with the help of my dad (who has been tuning for years on the evoX and WRX) and weve run into a stange issue.
the target AFR seems to be one count leaner than the tables suggest it should be on spool up. we have the WGDC set to 66% from factory across the board as to not overboost the vehicle while we dial in the tune. I also noticed my load targets are off, and am wondering if the WGDC and load targets are joining forces to cause this issue.
MAF scaling for COBB SF intake from @Mituc have been loaded onto the car to make sure it wasnt a MAF scaling problem on our end.
This issue really only occurs before 4000 rpm. everything past looks good.
Thanks in advance!

Hi!
Please take a log reproducing the problem that you have but use this preset: https://www.dropbox.com/scl/fi/afnzjbrr ... tiu1j&dl=0

If possible (no intellectual property stuff involved such as tune from a professional tuner and so on) please also share your tune. If you don't want to post the tune on the forum at least send it to me in a PM (but again please make sure it's not a tune from a pro, these tunes are not supposed t be shared).

Does anyone know how the "desired AFR" is calculated? Is there and series of lookups and factors that are multiplied to the "target AFR" listed in the tune?

The desired AFR should normally be the target AFR from the corresponding AFR table: closed loop, open loop, WOT or overload.

However, these values are then interpolated with the values from the Knock AFR tables if there is any knock and also some other tables that I don't think are exposed yet and are temperature dependent (most likely BAT, just like the High BAT/ECT ignition retard tables).

Also, when the stability control module sends various signals the ECU will enrich the mixture (and also pull timing) to reduce the power output. That will reflect into the desired AFRs as well.