So my car seems to be running lean then goes to rich. Specifically lean 1.0 to then .69 rich. Does anyone have any insight on what this number should be around and what could be causing it to do what it's doing? 2010 sho non pp. roughly 45k miles. Completely stock. No check engine lights. Just reading numbers and getting a baseline before tuning. But as of now the tunes are on hold. Thanks in advance for the help. No warranty and whatever work is to be done will be by me. Just thought I'd come here first to see what kind of help I can get!

Probably normal for bone stock.  OEM tunes do run richer at heavy throttle than aftermarket tunes, one way to combat engine kaboom tendencies perhaps.  This makes the stock SHO somewhat of a portly racer compared to the lean speed racers that result from aftermarket tunes.

Let me check my logs, but I recall these cars running stupid rich stock under load... I recall seeing .6X...


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It just seems odd how it goes from 1.0 to .69 doesn't that seem like a far fluctuation?

Need a datalog ....not good to look at max and min values from a drive session....there are times of runout and tip ins where you can be very rich or lean for a split second....best to look at specific areas when evaluating things and not just the mins and max...have you logged a wot pull?

Not sure if you are logging with SCT or not.. but here is a stock datalog... in second gear under WOT I am seeing .68 lambda... and I start at 1.02 before mashing the pedal...

Purple is gear, gold is RPM, and red is lambda(AFR)...

I seem to recall the stock lambda target being somewhere in the .7x so definitely could see going to .69 on a hard tip in event. And it always will lean out when there is no pedal input/on tip out for emissions and fuel economy reasons.

Typically you should expect to see somewhere between .82-.87 once tuned for your lambda target.

Post a log up!

Quote from: derfdog15 on January 30, 2017, 08:52:15 PM
I seem to recall the stock lambda target being somewhere in the .7x so definitely could see going to .69 on a hard tip in event. And it always will lean out when there is no pedal input/on tip out for emissions and fuel economy reasons.

Typically you should expect to see somewhere between .82-.87 once tuned for your lambda target.

Post a log up!

Depending on year maybe? My lambse WOT at the end of second into third is .68... I have a 2010...

.82-.87 is probably accurate if your tuned for E20... .80 is what I see most guys running tuned at least in the SCT tuned world...


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Quote from: StealBlueSho on January 30, 2017, 09:06:39 PM

Quote from: derfdog15 on January 30, 2017, 08:52:15 PM
I seem to recall the stock lambda target being somewhere in the .7x so definitely could see going to .69 on a hard tip in event. And it always will lean out when there is no pedal input/on tip out for emissions and fuel economy reasons.

Typically you should expect to see somewhere between .82-.87 once tuned for your lambda target.

Post a log up!

Depending on year maybe? My lambse WOT at the end of second into third is .68... I have a 2010...

.82-.87 is probably accurate if your tuned for E20... .80 is what I see most guys running tuned at least in the SCT tuned world...


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You may be correct, I just looked at my one stock log (I am amazed AJPTurbo had the patience to look through it) and my rang was .7 to 1.05 on stock logic and 93 octane.

My last Rev of 93 (rev6) range was from .79 to 1.01.

Most recent E20 rev (rev21), .79 to 1.05 and I believe my target is .85 while WOT.

Logs attached. Enjoy!

Desired Lambda at WOT for a 2010

Desired Lambda at WOT 2015

Those are for open loop basically....All other times at closed loop it will be 1.0

Quote from: AJP turbo on January 30, 2017, 10:22:28 PM
Desired Lambda at WOT 2015

Those are for open loop basically....All other times at closed loop it will be 1.0

What's the X axis referencing?

Definitely different though, I wonder what drove that change.

Quote from: derfdog15 on January 30, 2017, 10:25:19 PM

Quote from: AJP turbo on January 30, 2017, 10:22:28 PM
Desired Lambda at WOT 2015

Those are for open loop basically....All other times at closed loop it will be 1.0

What's the X axis referencing?

Definitely different though, I wonder what drove that change.

coolant temp

Quote from: AJP turbo on January 30, 2017, 10:22:28 PM
Desired Lambda at WOT 2015

Those are for open loop basically....All other times at closed loop it will be 1.0

God i wish you'd post more screenshots like that just to give an idea of what the tuning  tables look like. That one is almost surprisingly simple! . . i'm sure i'm being naive though

Okay here is the log from the sct x4. Run is a second gear pull 2k rpms to 6500, wot. The gold line is rpms the red is afr bank 2 the green is afr bank 1. The car is on the oem tune with 93 octane. Outside air temperature was about 55 degrees.