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.

 

the TC's can run leaner due to direct injection. your good

 

so what should a TC's approximate air/fuel ratio

 

i am not too familiar with direct injection but synapses turbo kit dyno vid had AFR at 12.5

 

Tuned you should be around 12.8-12.9 and stock around 12.04 is what my car ran according to HPT.

 

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.

 

I didnt know are cars came with a wideband are you sure on that?

 

My RPD has a wideband...

 

Yes they have a factory wide band you just need a way to read it.

 

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

 

Actually at idle it is 14.7 it actually run on the stoich command.

Let me rephrase that the LNF cars have the wideband not all the 08's-09's

 

Yep. At idle my A/F is also at 14.7.

 

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.

 

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.

 

Ok cool I was just seeing because alot of my turbo info comes from my friend who all have SRT4s. It makes more sense because theirs is alot richer since their air/fuel mixture happens in the intake manifold rather than in the piston chamber like ours does.

my idle is a little higher. its about 15.3

 

still normal mine goes between 15.5 and 14.5 at idle but tries to stay around 14.7

 

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

 

Tuning the fueling on a DI car is not dificult at all. Especially if the car has a factory wideband like the TC. It will see the exact A/F you command unless your MAF tables are screwed up.

 

Now I thought there is a big difference between Commanded AFR and actual.

I can't read actual with my DashHawk, just commanded.

 

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.

 

I don't have an RPD, just a DashHawk. Will the DashHawk even read actual?

 

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.

 

if it's reading what your wideband is saying...then that is actual. I've never looked at a dashHawk on the LNF before, so I couldn't tell you for sure.

 

shut up you women beater

 

? That came out of nowhere.....