I am running a WB O2 and it is reporting around 15.5 AFR I am trying to get closer to 14.7-14.5. I have disabled the MAF and put the PCM into SD mode, but when I modify the VE table the PCM just corrects to its measured stoich (via NB O2's) Basically it just pulls out any fuel I add. Is there a way to modify or offset what the NB O2's perceive as stoich to better match my WB? I can always tune it in open loop but Id rather not.
What's your cam?
If it's big enough, you may need to operate in open loop at idle. The overlap will trick the O2s (wideband included) into thinking you're running leaner than you are at idle.
Big cams also like to run leaner than stoich.
Make sure your Narrowband O2s are set to 450mV... if it's still adding fuel in closed loop try them at 300mV.
Its a stock cam. I will play around with the O2 voltages to see where it will work. I have a little more faith in the wideband then I do the narrow bands.Originally Posted by JakeFusion
O2 voltages and stoich fuel settings. Don't bother setting stoich any richer than 16.0 to 16.5 as the O2's will just pull it back out... In other words everything has to correspond.
Question though. When you put it into VE, did you fail the MAF correctly. Set dtc's to 1st error no ses light? Otherwise you may just be fighting your MAF if it's not failed correctly.
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I'm running a flex fuel OS so the stoich is tricky.
Yes it failed correctly, I set it to no light and the code was indeed set.
I think you may simply be seeing sensor error due to excess
exhaust oxygen. This can come from cam overlap (not stock,
but anything bigger), misfires / weak spark, injector imbalance.
The LSU4 sensors are no different or better than NBO2s in
this respect. Same material system basically, just smarter
and tighter control electronics.
Moving the idle-airflow-mode-range O2 sensor voltage will
move the pivot AFR. Where 350mV gives 14.7, 500mV (in
my limited observation) makes 13.5:1.
But you're misplacing your faith if you tune to a WBO2
number, and not minimum-MAP. Max vacuum, shade tree
style, is how to set idle mixture still. If 16:1 on the meter
is your happy place, then screw the meter.
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