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AFR

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#1
2016 Stage 3 fiesta ST hitting 40s AFR on decel, is that normal for these cars or no?


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OP
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Thread Starter #5
But doesn’t that mean it’s running lean?


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Spork1569

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#6
But doesn’t that mean it’s running lean?


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There's times when the car doesn't run at 14.7 afr. Under boost you'll likely notice in the 11 to 13 range and that's because the fuel is used to aid in cooling the engine down.

My guess is it's programed to run leaner while coasting for fuel efficiency, but it could be due to other reasons.
 


OP
S
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Location
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Thread Starter #7
There's times when the car doesn't run at 14.7 afr. Under boost you'll likely notice in the 11 to 13 range and that's because the fuel is used to aid in cooling the engine down.

My guess is it's programed to run leaner while coasting for fuel efficiency, but it could be due to other reasons.
Ok thank you!


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Ford ST

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#8
From what I understand when your foot is off the gas and you're coasting it actually completely cuts fuel. Maybe this doesn't apply to all vehicles, but anyway it's very normal.

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