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air/fuel ratio's

your fine. At idle.... 14.7-15.5 is normal. I see that with mine all the time. If your WOT, then I would be worried.

For fuel economy, there's a lot more to do with that, Air/temp, humidity, rpm, gear, ratio, resistance, ect.
 

Justin

Save the dawn for your dishes!!!
idle and part throttle 14.7 is the perfect mix of air and fuel. while it would be great if a car could run that at WOT it just cant as it would detonate badly and blow up. So during cruising when there isnt a load on the car you want to see around those numbers you listed as this is how you get better MPG then when you give it the go juice it will richen the mix advance the timing etc.
 
This can be a tricky subject, but I'll do my best to explain how Ford's use the O2's.

It's best to talk about Lambda as Air/Fuel changes from Wideband to wideband depending on how it's programmed, but Lambda is always the same. IE, 1.0 Lambda = stoich, regardless of fuel used. Stoich is the theoretical Air Fuel at which the mixture burns complete.

At Idle and Part throttle Ford's target 1.0 lambda.
At WOT these Fords target .82 to .85 lambda. (factory fuel curve)

100% gasoline has a stoich of 14.64
E10 fuel has a stoich of 14.08
E15 13.6
E85 9.7

ALL of which are 1.0 Lambda at that Stoich A/F!

Now, these new Fords are programmed for E10 fuel so Stoich is programmed at 14.08, unlike older Fords with Stoich programmed as 14.64. This value is multiplied by ALL fuel and Maff tables to provide a 'base' fuel curve. The O2 sensors then 'correct' any deviations as Short and Long term fuel trims. (short is instant, long is learned and saved in KAM memory).

So, the 2011+ Copperhead ECU says 1.0 lambda is 14.08. If you were to monitor Air Fuel via track apps in a 13 you'd see the readout as 14.08 at idle and part throttle. Now, stick an NGK AFX in the same 2013 and it will read 14.64! Why? Because MOST aftermarket widebands are programmed for 1.0 lambda = 14.64:1 for gasoline.

This is why you will see a dyno graph wideband read 12.4 and yet the ECU is reading 11.9! (The air fuel is IDENTICAL, it's the programming of the Widebands that differs). A LOT of tuners get caught up in Air Fuel when Lambda actually simplifies things.

Easy way to look at it:
Lambda x stoich = Air Fuel ratio

IE, .85 lambda x 14.64 = 12.44
.85 lambda x 14.08 = 11.96

Now, to throw in another variable.... Our gas today varies from No Ethanol to 15-20% in some cases (excluding E85). How does Ford account for these variances? Fuel trimming. As stated above at idle and part throttle the O2's target 1.0 lambda, regardless of stoich and the variance is recorded as Fuel trims. same goes for WOT as these cars trim the fuel curve at WOT based on Lambda target vs actual.

What this means:
If you run Zero Ethanol fuel you're fuel trims will read rich at idle / part throttle and WOT (ECU leaning out the mixture)
If you run 10 your fuel trims will be SPOT ON
If you run E15 your fuel trims will read lean. (ECU richening up the mixture)

Actual Lambda vs fuel will be identical in a vehicle that runs E0, E10, E15, etc. (ECU automatically compensates)

O2 sensors read the Oxygen left after the burn process. Stoich is stoich (and the O2's find it), lambda is lambda. Air fuel is a mathmatical calculation from both.
 
Kenaizer said:
Show off...
LOL That's nothing, try working with multiple regression models. :'(

Shaun thanks for the detailed explanation.
 
Shaun thank you for your detailed explanation. I got a cai from steeda and tuned with a programed track key which I was now told is a mistake. So I went back to stock and put the track key away and tuned with the street key.Now everything is running perfect. Nobody told me you can't tune with the programed track key,another lesson learned!
 

ace72ace

Zaino, I put that $hit on everything
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CaliMR said:
Shaun, other people have posted here that our cars use widebands instead of regular 02 sensors. Is that true?

CoolTech also verified this on the '12s in their Kooks exhaust thread over on TMS when they stated you can run the headers w/o a tune because the widebands adjust the A/F and saw IIRC that it ran a little richer after installing the Kooks LT headers & pipes.
 
Hey do you guys think its normal to running A/F of 12.0 at WOT. I dyno'd mine with the track key Each pull was a flat line of 12.0 across the RPM range. Isn't that too rich? Also torque peaked @ 4700rpm and continually went south from there.374.3whp/338.32wtq
 
Thats about right for WOT. You never want to run to lean.I ran 12.4 with hp tuners on a ls2 2005 gto and with the e10 sounds like you are right on.
 
KIRKO said:
Hey do you guys think its normal to running A/F of 12.0 at WOT. I dyno'd mine with the track key Each pull was a flat line of 12.0 across the RPM range. Isn't that too rich? Also torque peaked @ 4700rpm and continually went south from there.374.3whp/338.32wtq

Commanded lambda on the Track Key is .860.
 
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KIRKO said:
Hey do you guys think its normal to running A/F of 12.0 at WOT. I dyno'd mine with the track key Each pull was a flat line of 12.0 across the RPM range. Isn't that too rich? Also torque peaked @ 4700rpm and continually went south from there.374.3whp/338.32wtq

Commanded lambda on the Track Key is .860.

and part of the problem why the trackey pings?
 

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