Ecoboost AFR

[17Stallion]

2017 Ecoboost Premium. Only "performance mods" so far (only had it a month) are MBRP cat-back and AEM dry flow filter.

When driving AFR is normally 13.9-14.2. When driving on highway and I let off the gas the AFR will go above 20 and stay there for a significant amount of time. Coasting at other than highway speeds it will maintain the same 13.9-14.2 AFR. I saw reference to 22+ being the EFI lean burn limit. So is what my car doing normal?

Thanks

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[smann]

Perfectly normal

 

[Marvinmadman]

Yep, normal. Let off the throttle and it cuts fuel while "engine braking"

 

[17Stallion]

Thanks

Thought that might be the case, but after reading a thread about the fuel pressure sensor, I wanted to make sure.

 

[Brian V]

This would be defco. De acceleration fuel cut off . For fuel economy

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