How to tell if AFM is active?

[Saltydog]

Wow I also have a 5.3 on my 2023 Yukon slt. How do you get such good mileage on the hwy? I think the best I have gotten is around 24mpg driving around 60mph. I generally drive very mild (no harsh acceleration and lots of coasting).

I have seen about 29 MPG with 21 Yukon 5.3, normal Highway is about 24-26mpg.

 

[Saltydog]

I have enough seat time in our Yukon and I can tell by the throttle response and the engine/exhaust sound when DFM is active.

That said, GM did a very good job of masking the sound of it.

 

[Doubeleive]

How can I tell if AFM is active? In the previous gen Tahoe/Yukon, I was able to see V8 icon change to V4 in the instrument cluster.

you should be able to feel it and hear it, it drives me absolutely insane.

 

[B520044]

you should be able to feel it and hear it, it drives me absolutely insane.

Drives me crazy too. I feel it more than anything. To me its like driving a manual transmission in the highest gear when going 40mph.

 

[greg_tahoe84]

Is the newer DFM any better?

 

[Doubeleive]

Is the newer DFM any better?

it's just a jig to keep the epa happy, doesn't help the consumer in any manner

 

[vcode]

Same here....how are you getting 29? removing extra seats, spare, etc?

Note his best and average mpg's are the same. Doesn't compute.