Afr
Supporting Vendor
Joined: Aug 2007
Posts: 1,452
Likes: 86
From: CT
you'd be at part-throttle (closed loop), so your AFR will always be around 14.7... which is the stoich value that it should be at...
__________________
06MonteSS / DiabLew Tune
2014 Camaro 2SS/RS LS3, short-throw shifter, NPP perf. exhaust, BMR strut-tower brace, Cold Air Inductions cold air intake, catch-can, ported/polished TB, Custom DiabLew Tune
www.diablewtune.com -- www.diablocustomtune.com -- www.diablocustomtunegm.com
06MonteSS / DiabLew Tune
2014 Camaro 2SS/RS LS3, short-throw shifter, NPP perf. exhaust, BMR strut-tower brace, Cold Air Inductions cold air intake, catch-can, ported/polished TB, Custom DiabLew Tune
www.diablewtune.com -- www.diablocustomtune.com -- www.diablocustomtunegm.com
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
11.9 in power enrichment or WOT is the stock programmed AFR--Its pig rich that way from the factory---tuning will add some HP by leaning it down some--On a DD car i normally set it at a safe 12.4-12.5 on a more performance level you can go like a 12.7-12.8 and on a race only application maybe 12.9-13.0
20.0 in "closed loop" or during P/T has to be an error--the stoich value as mentioned should be 14.7 so if it is in indeed 20.0--it is parts breaking lean---i wouldn't drive it that way--
If you have a LM1 wideband---the callibrating AFR when the unit is turned on before starting is 20.90 maybe somehow this value is stuck in your waideband an it's not reading correctly--try re-calibrating the unit
Do you have any mods ?? have LT headers ???
20.0 in "closed loop" or during P/T has to be an error--the stoich value as mentioned should be 14.7 so if it is in indeed 20.0--it is parts breaking lean---i wouldn't drive it that way--
If you have a LM1 wideband---the callibrating AFR when the unit is turned on before starting is 20.90 maybe somehow this value is stuck in your waideband an it's not reading correctly--try re-calibrating the unit
Do you have any mods ?? have LT headers ???
Thread Starter
Melting Slicks
Joined: Apr 2007
Posts: 2,086
Likes: 0
From: Meeker OK
Mods are heads,cam,intake,exhaust, bigger injectors, fuel rails, and a boostapump. I'm running a NOS launcher with a wideband O2 to monitor and shut down in case of a lean condition. This particular setup isn't able to calibrate as far as I can tell. There is no cal. procedure in the install doc anyway. I think I will take it to a friend that is a tuner and has a Mustang dyno and have him hook up his wide band to compare. Never the less I'm not sprayin till I get this figured out
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
Tech Contributor
Joined: Sep 2005
Posts: 1,731
Likes: 82
From: New Market AL
There are ways to force the ECM into open loop at specific rpm ranges. Some tuners like to keep the computer in open loop at idle through 1200 rpm. There is no good reason for you to see a steady 20 AFR at low rpm cruise. That tune needs to be addressed. Hope your tuner knows all the values for the specific injectors you are using. It makes a big difference in idle and low rpm performance.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
ALSO---trying to get an accurate AFR at 1500 RPM is pretty tough anyway---Thw wideband tends to bounce around all over the place---Another thing to consider is that when "lifting" the DFCO system becomes active (decel fuel cut-off) when active the ECM shuts the fuel OFF and the wideband will show it's max AFR cause there is NO fuel present- P/T AFR tuning can't be done on a dyno anyway--has to be under normal street driving-- and the fuel should always be trying to correct itself automatically to 14.70 with data rec from your front 02's via your fuel trims-----
