AFR question

[turboffr]

Anyone have an idea why my WOT AFR would be 10.4-10.5 when commanded was AFR was 12.5? Nothing was changed in the tune. The tune was spot on and has been for some time, but I was at the track and the car started slowing down on me. I checked the scan and noticed the AFR was really rich (mid 10's). Before this happened the AFR error was within 1% of wideband on the street and on the dyno.

The temp was about 10 degrees hotter than when I was on the dyno, not sure if that makes a difference. Car is an '06 vette, running MAF only tune. COT is not enabled.

I've attached the scan. The issue starts at frame 2760.

[turboffr]

here's the tune in case someone wants to take a look. I can't see anything that would have caused it to go pig rich, but I'm just a rookie. The only thing I can think of is the temp. It was around 82 with some humidity and I had been tuning the car around 72 degrees. Something just doesn't seem right.

[turboffr]

ttt - anyone ever experience this? I tuned the car in open loop with a wideband to get the MAF curve dialed in. fuel trims are negative at WOT. I'm stuck

[thesubfloor]

ttt - anyone ever experience this? I tuned the car in open loop with a wideband to get the MAF curve dialed in. fuel trims are negative at WOT. I'm stuck

You've got a wiring issue with your wideband as it's probably shorting out or losing power based on how flat the readings are.

If you fire up the car and start scanning but physically unplug the wideband connector from the interface you'll see what I'm talking about because even with it not hooked up the scanner will show a low and consistent reading.

[Mep_q8]

what fuel are you using?

The file you posted up shows a commanded PE afr of 12.94 and in your scanner it shows a commaned of 12.5... Pull the tune on the motor now and post it up..

but looking over the scanner, it does look like a wb02 issue more then anything else..

[turboffr]

what fuel are you using?

The file you posted up shows a commanded PE afr of 12.94 and in your scanner it shows a commaned of 12.5... Pull the tune on the motor now and post it up..

but looking over the scanner, it does look like a wb02 issue more then anything else..

Stoich AFR is set at 14.20 since the fuel is a 10% enthanol blend.

[turboffr]

You've got a wiring issue with your wideband as it's probably shorting out or losing power based on how flat the readings are.

If you fire up the car and start scanning but physically unplug the wideband connector from the interface you'll see what I'm talking about because even with it not hooked up the scanner will show a low and consistent reading.

I believe you're correct. I unhooked it today and AFR were in the 10's. I also did a comparison of the log attached to this thread to one of my older logs. Both logs showed similar O2 voltages under WOT