Nominal AFR: 14.0

[limequat]

Anybody know why Ford does this? It's -like- tuning 101 to set AFR to stoich for the best combination of fuel economy, emissions, and power. It'll go rich for power, but just cruising, it always wants to be 14.0. Seems like fixing this would be a quick way to come up with another MPG or two.

But Ford MUST have a reason. Right?

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[BGolden]

Stoich for E10 is 14.08. Chevy does it as well now

 

[Anthony@FFtec]

There are trace amounts of Ethanol in the fuel.

Stoich point is based on the presumed ethanol content present (E10).

Anthony

 

[tmcphail]

I setup my calibrations for 14.7 at cruise and pickup 1-2 MPG on that alone.

 

[TurboAg]

Yeah I've noticed Torrie's tune hovers around 14.7 under lighter throttle, etc

 

[tmcphail]

Yeah I've noticed Torrie's tune hovers around 14.7 under lighter throttle, etc

Precisely!

 

[mizer67]

Yeah I've noticed Torrie's tune hovers around 14.7 under lighter throttle, etc

Is there any downside to leaning it out under light throttle?

Why does Ford run it at 14.0 if it's an easy mpg improvement for CAFE? (The tests are done primarily under light loads)

 

[tmcphail]

No.
Most likely emissions output.

 

[limequat]

No.
Most likely emissions output.

IIRC, NOx emissions skyrocket in lean mixtures.

 

[limequat]

 

[EngieKev]

Remember that all pumps, with exception, are E10 fuel. Nominal AFR for E10 is 14.08.

Even if you change nominal AFR the system will adapt to run stoich, its a closed loop system. Any MPG gains are speculation or before the system is learned.

 

[tmcphail]

You can independently command the lambda you want in all conditions.

 

[EngieKev]

You can independently command the lambda you want in all conditions.

Yes but that is a dial which will override all other request, including hardware protection.

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