A/F Ratios... at what point are you "lean" or "rich"?
05-21-2010, 03:55 AM
#2
3rd Gear Member
Join Date: Mar 2009
Location: NOLA
Posts: 665
i think 14.7 is your target number. any less is rich, any more is lean
edit: of course, how rich or how lean is the next question. if you're at 14.2, you wouldn't really be considered as running rich, just richer than whats considered "normal"
edit: of course, how rich or how lean is the next question. if you're at 14.2, you wouldn't really be considered as running rich, just richer than whats considered "normal"
Last edited by trailor; 05-21-2010 at 03:57 AM.
05-21-2010, 06:09 AM
#3
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
The stoichiometric AFR for gasoline is 14.7:1, this is the ratio at which the fuel is burned completely. As stated above any ratio less that that is considered rich, a ratio greater than that is considered lean.
For a naturally aspirated gasoline engine air/fuel ratios of 12.5:1 to 13.0:1 generally produced the most power, ratios of 15.0:1 to even 16.0:1 produce the best fuel economy--at the risk of increased emissions so you do not see many engines running that lean anymore.
Most modern EFI engines target 14.7:1 in closed loop operation, and 12.0:1 to 13.0:1 in open loop...
For a naturally aspirated gasoline engine air/fuel ratios of 12.5:1 to 13.0:1 generally produced the most power, ratios of 15.0:1 to even 16.0:1 produce the best fuel economy--at the risk of increased emissions so you do not see many engines running that lean anymore.
Most modern EFI engines target 14.7:1 in closed loop operation, and 12.0:1 to 13.0:1 in open loop...
05-23-2010, 12:43 AM
#5
4th Gear Member
Thread Starter
Join Date: Mar 2009
Location: NC
Posts: 1,909
ok so the higher the number the leaner the mixture is? I let my tuner deal with all that stuff but I want to know for future reference if I every buy a A/F gauge..
So what is a example ratio that is basically a red flag for tuning? and Cliffy, is closed loop operation what your car is pretty much in unless its WOT?
Until I can switch my MAF, my tuner said that he cannot get the "cursing" A/F working correctly (too much voltage fluctuation in the meter due to turbulent air (and possibly the MAF screen I left in there on accident
), but its fine at WOT
So what is a example ratio that is basically a red flag for tuning? and Cliffy, is closed loop operation what your car is pretty much in unless its WOT?
Until I can switch my MAF, my tuner said that he cannot get the "cursing" A/F working correctly (too much voltage fluctuation in the meter due to turbulent air (and possibly the MAF screen I left in there on accident
), but its fine at WOT
05-23-2010, 11:49 AM
#7
4th Gear Member
Thread Starter
Join Date: Mar 2009
Location: NC
Posts: 1,909
what is maf backwash? and what are the causes/fixes? This is just while the cars "lugging" I guess is the term. Not WOT. If you were to be in 4th cruzing at 2k rpms and trying to maintain 2k rpms is when the problem arises....
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