Short term fuel trim question

[JT-A4B7]

Is it normal for your stft to zero out under WOT?
I had a b7 a4 that would show the corrections at WOT
all the way through the rpm range. I figured the b5 s4 would do the same.

[RMode]

Fuel trims aren’t used at WOT


Sent from my iPhone using Tapatalk

[CELison]

Narrowband O2s don't know what's going on at WOT.

[JT-A4B7]

So how does the ecu know if it's going lean or not? EGT'S?
or maybe knock sensors?

[RMode]

So how does the ecu know if it's going lean or not? EGT'S?
or maybe knock sensors?

Correct. If your egts are working and not tuned out (many of us do, and run a wideband or 2), allows for fuel corrects in both open and closed loop.


Sent from my iPhone using Tapatalk

[CELison]

IMO, if you have anything other than a cookie cutter stage 1/2 tune, a wideband gauge is an absolute must.

[RMode]

IMO, if you have anything other than a cookie cutter stage 1/2 tune, a wideband gauge is an absolute must.

Absolutely agree


Sent from my iPhone using Tapatalk

[JT-A4B7]

Can the wide band be connected to the ecu?

[CELison]

Can the wide band be connected to the ecu?

It can for logging by tapping into a rear 02 plug you're not using. But as far as I know, nobody is able to use it to adjust fueling at WOT in real time. Maybe Philadot? Not sure.

[RMode]

Also important to note, the car doesn’t use STFT/LTFT in the traditional sense. It shows idle trim (1/3 in block 32), and cruising/light throttle (2/4 or block 32). This is because it’s a torque based egt mgmt setup.


Sent from my iPhone using Tapatalk