Air/Fuel Ratio for LNF??
03-03-2009, 09:59 PM
#1
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Air/Fuel Ratio for LNF??
What is the correct air fuel ratio for our LNFs? I just installed my AEM UEGO on my TC and the lowest air fuel that I saw on full throttle was a 12.2. Is this lean for our cars?? Please keep in my of my mods I have. I need feedback. 
03-03-2009, 10:29 PM
#6
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You didn't need to get the aem wideband since we already have one, you could of gotten the aeroforce/dashhawk/dashdaq to simply read it.
As for the afr, it starts at 14:1 at low rpm and drips down to 12.7 past 5300rpm.
As for the afr, it starts at 14:1 at low rpm and drips down to 12.7 past 5300rpm.
03-03-2009, 10:35 PM
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I have an 08 I know of a few cars have a wideband maybe the 08s dont and 09s do? i havnt really read into that anyway Ill figure it out sorry sorry to thread jack
oh ok thanks just learned something new
oh ok thanks just learned something new
Last edited by stg2ss; 03-03-2009 at 10:35 PM. Reason: Automerged Doublepost
03-03-2009, 10:37 PM
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Let me rephrase that the LNF cars have the wideband not all the 08's-09's
Last edited by jwhitten; 03-03-2009 at 10:37 PM. Reason: Automerged Doublepost
03-03-2009, 10:56 PM
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Ok when going full throttle,ive noticed when i rode in my friends SS/TC that it hits like 14.8 then gradually lowers until around 12.5 and its sits around there until about 6k rpm and then itll drop to like 11.8 which from my understanding of must turbo cars a 12 anything is cutting it really close when it comes to running to lean.i kno that Direct injection is different than your regular fuel injected engine and ive been doing some research and there are alot of techs out there saying that it is almost impossible to tune cars with direct injection. because of the different fuel points and curves.so my question is just how safe is it to run a turbo car at 12.5 afr. especially one with aluminum block and heads.
03-03-2009, 11:04 PM
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Well I have been running mine with a AFR of 12.8 for over 6 months and constantly put it into boost with no problems. This is a direct injection which requires miniscule amounts of fuel as compared to a regular engine. I f you look at the tail pipe on any of the LNF cars you will see that its still running rich enough to make black smoke.
03-04-2009, 12:41 AM
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Well I have been running mine with a AFR of 12.8 for over 6 months and constantly put it into boost with no problems. This is a direct injection which requires miniscule amounts of fuel as compared to a regular engine. I f you look at the tail pipe on any of the LNF cars you will see that its still running rich enough to make black smoke.
my idle is a little higher. its about 15.3
Last edited by Hotshot768; 03-04-2009 at 12:41 AM. Reason: Automerged Doublepost
03-04-2009, 05:21 AM
#17
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Air / fuel ratios always threw me off. I'm pretty sure 14.7:1 being stoichiometric means there are 14.7 parts air : one part fuel.
An air mixture <14.7 = rich mixture. There is actually less air or more fuel, meaning you're running rich.
If air is >14.7 = then the mixture is lean.
"...A mixture is the working point that modern engine management systems employing fuel injection attempt to achieve in light load cruise situations. For gasoline fuel, the stoichiometric air/fuel mixture is approximately 14.7 times the mass of air to fuel. Any mixture less than 14.7 to 1 is considered to be a rich mixture, any more than 14.7 to 1 is a lean mixture - given perfect (ideal) 'test' fuel "
http://en.wikipedia.org/wiki/Air-fuel_ratio
An air mixture <14.7 = rich mixture. There is actually less air or more fuel, meaning you're running rich.
If air is >14.7 = then the mixture is lean.
"...A mixture is the working point that modern engine management systems employing fuel injection attempt to achieve in light load cruise situations. For gasoline fuel, the stoichiometric air/fuel mixture is approximately 14.7 times the mass of air to fuel. Any mixture less than 14.7 to 1 is considered to be a rich mixture, any more than 14.7 to 1 is a lean mixture - given perfect (ideal) 'test' fuel "
http://en.wikipedia.org/wiki/Air-fuel_ratio
03-04-2009, 09:05 AM
#18
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Ok when going full throttle,ive noticed when i rode in my friends SS/TC that it hits like 14.8 then gradually lowers until around 12.5 and its sits around there until about 6k rpm and then itll drop to like 11.8 which from my understanding of must turbo cars a 12 anything is cutting it really close when it comes to running to lean.i kno that Direct injection is different than your regular fuel injected engine and ive been doing some research and there are alot of techs out there saying that it is almost impossible to tune cars with direct injection. because of the different fuel points and curves.so my question is just how safe is it to run a turbo car at 12.5 afr. especially one with aluminum block and heads.
03-04-2009, 09:16 AM
#20
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Ok when going full throttle,ive noticed when i rode in my friends SS/TC that it hits like 14.8 then gradually lowers until around 12.5 and its sits around there until about 6k rpm and then itll drop to like 11.8 which from my understanding of must turbo cars a 12 anything is cutting it really close when it comes to running to lean.i kno that Direct injection is different than your regular fuel injected engine and ive been doing some research and there are alot of techs out there saying that it is almost impossible to tune cars with direct injection. because of the different fuel points and curves.so my question is just how safe is it to run a turbo car at 12.5 afr. especially one with aluminum block and heads.
also, with the DI motors...since the fuel in directed right into the combustion chamber it is much more efficient. So you get a better burn and utilize the fuel better then a standard fuel injector set up, which in turn allows you to not inject as much fuel.
commanded is what your PCM is trying to acheive.
Actual is what your wideband is picking up, what is actually happening. If you're looking at the reading on your factory wideband, that is the actual not the commanded.
Last edited by Sunburst_SS; 03-04-2009 at 09:16 AM. Reason: Automerged Doublepost
03-04-2009, 09:21 AM
#21
also, with the DI motors...since the fuel in directed right into the combustion chamber it is much more efficient. So you get a better burn and utilize the fuel better then a standard fuel injector set up, which in turn allows you to not inject as much fuel.
commanded is what your PCM is trying to acheive.
Actual is what your wideband is picking up, what is actually happening. If you're looking at the reading on your factory wideband, that is the actual not the commanded.
commanded is what your PCM is trying to acheive.
Actual is what your wideband is picking up, what is actually happening. If you're looking at the reading on your factory wideband, that is the actual not the commanded.
03-04-2009, 09:26 AM
#22
Senior Member
If your MAF is tuned properly ie. stock intake. the actual and commanded A/F should be exactly the same. This car has a factory wideband and no VE tables.
? That came out of nowhere.....