Running Rich or lean?

[burnt01ss]

How do i know if i'm running rich or lean. Is there a general # that the O2's should be reading or what?

[Magic_Chicken]

I don't know much about O2 numbers yet, but as for LTFT's, if they are negative you're running rich, if they are positive you are running lean. Negative means it's taking away fuel because of a rich condition, positive means it's adding fuel because of a lean condition.

MC

[Casey]

How do i know if i'm running rich or lean. Is there a general # that the O2's should be reading or what?

The O2 numbers won't tell you much. The narrowband sensor can only read 14.7. The VCM learns by the amount of time is spends being rich or lean and then makes adjustments.

Use the LTFT histogram to get a complete picture of whether you are rich or lean. Keep in mind, that is only for closed loop fuel. If you are doing full throttle passes you will need a wide band O2 sensor.


Ken

[jimmyblue]

Actually, the LTFTs indicate that you -would- be
running rich (- values) or lean (+ values) >if< the
PCM weren't correcting things. The closed loop
makes the mixture as close to dead even as it can
manage. Once you go to WOT though, all is laid
bare. Though if you had positive trims you will be
given a damp towel to cover that embarassing
lean condition.

LTFTs are the gauge of your system's calibration
accuracy at various points. The further away from
WOT they are, the less relevant in my book (like
don't worry about the idle, decel and Cell 0 values
as much as what you see in the higher-MAP, higher-
RPM ones).

O2s are not accurate away from 14.7 but you can
still get something of an idea. For best power you
want about 12.8:1 (some like as lean as 13.0:1 on
these LS-1 motors, but I'd stay a bit fatter). If you
are seeing less than 850mV you will probably be into
pinging/KR at WOT. 900mV is a pretty good place to be.
Over 920mV at WOT could stand a few less carbs.

[03EBZ06]

I find the o2s are quite accurate for tuning. With stock around 890mv, I can see a direct and constant change after tuning. If you don't have a wideband, you can use them.

[Dom]

I find the o2s are quite accurate for tuning. With stock around 890mv, I can see a direct and constant change after tuning. If you don't have a wideband, you can use them.

My O2s show 890mV right now. Should I be happy with this or try to change the air/fuel. I'll dyno as soon as the weather gets cooler, for now it's all O2s.