Bill00Formula

iTrader: (4)

And then at the commanded afr (based on the PE modifier) when close to full throttle? This is assuming a MAF tune.

How much variation is there? thanks

redtan

iTrader: (5)

It should run at 14.7 at all situations even not tuned, that's what the oxygen sensors are there for.

With a good tune, the commanded AFR is what the car should see...but that all depends on the quality of the tune.

flame

iTrader: (13)

In closed loop with fuel trims on it will try and maintain 14.6 then when it goes into PE it should match what is being commanded. How much variation depends on how close the tune is.

ejbta

It should run 14.7 cruising down the hwy. At wot it should be 12.4 to 12.8.

RevGTO

iTrader: (12)

There can be some variation, especially with LT's since the O2's rarely work as they should with them. Even after extensive experimentation, my car tends to run a little lean when stoich is commanded - 14.85 to 15.00. Not an issue as there are not cats to protect. In PE mode, it's pretty much as commanded.

SexyTransAm

iTrader: (6)

like it lean at wot dont ya

redtan

iTrader: (5)

Wouldn't call 12.4-12.8 lean at all.

13.0 and higher...yes, mid 12s...no.

SexyTransAm

iTrader: (6)

i would all 12.5 and up lean at wot
lean is mean!

thunderstruck507

iTrader: (18)

My car runs in higher 14s-low15s at idle as well.

soundengineer

iTrader: (16)

12.5 is not lean....its usually a little on the rich side for WOT..
Try optimum at WOT closer to 12.9-13.1 on most of our naturally aspirated ls engines...

When you start to look at where our engines make power and when it starts to loose power..you will come to an understanding of what is lean and what is not..

I've seen combos that make great power with no detonation at
14.0..... If its safe, its not lean... It's just leaner than another combo might be.

Rich or lean is only relative to the combo it is with..

You start rich..,add timing until it stops getting better, then start removing or adding fuel until it makes the mist power..

Most people assume they are lean when they haven't even pushed the fueling to see what it really wants...

Rich and lean are not arbitrary numbers...and you can't call one afr or another rich or lean without the whole picture.


Example: my combo....12.9 @27* at WOT...
11.2 compression...
I ran a 10.97@123mph on Nitto Tires....and a stock 10 bolt with 3.42's

12.9afr is not lean for my combo.

ZL1Killa

iTrader: (17)

12.5 i would consider lean for FORCED INDUCTION.

naturally aspirated tend to like 12.7~12.9
you always have to be careful of cylinder 7....lol

joecar

It will run the stoich AFR when trimming is able to be done;

then when PE enables the commanded fueling will follow the PE table (note that PE can enable at part throttle, look at the PE Enable table).

Instead of thinking/viewing fueling in AFR, use EQR or Lambda, these will put rich/lean into easier to see perspective.


Any variation (barring noise) will be due to the airmass source (MAF or VE) not being correct (not modelling the actual cylinder fill airmass).

soundengineer

iTrader: (16)

12.5 is not Lean for Forced Induction of your motor wants to be there...
I have a buddy running 14psi with super charger and an air to water intercooler.... WOT, 12.5:1 AFR.. no issues...

and you can easily fix the #7 issues with proper steam venting...just buy the Kurt Urban fittings and take all the steam plugs to a higher position...
its only a problem because its a hot spot because steam gets trapped there.

ejbta

I got the 12.4 to 12.8 from a tuning article In high performance Pontiac.

ejbta

I have a wideband o2 meter in my car and it bounces from 14.5 to 15.0 driving down the hwy and it moves from 12.7 to 13.1 at wot

Tan327

iTrader: (15)

12.9-13.1 is ideal @ WOT N/A.