Any AFM indication without DIC?

[HeidiHoe]

I just don't get how people can not feel it, I can feel and hear everything my vehicle does, shifting, engine sound, braking, suspension. wind noise, you name it even though I have music blasting and subs bumping and rattling everything I can still hear and feel what my vehicle is doing I can tell when something changes, a different sound, a different squeak, a different feel. I guess it helps if you keep your vehicle maintained I can turn down the music and roll down the windows and roll down the road and my vehicles make no noise other than the engine running and tires rolling, the v4/v8 mode is 2 different sounds and if you are cruising it kicks on and off, there is a delay, you can especially feel it if you are cruising and just feather the pedal you can feel it kick on & off to me it is annoying as hell so I have it disabled.

The rpms also go up a bit when switching into V4 mode as it needs a bit more 'uhmf' to maintain speed with fewer 'live' cylinders

 

[Bill 1960]

The rpms also go up a bit when switching into V4 mode as it needs a bit more 'uhmf' to maintain speed with fewer 'live' cylinders

How is it possible for the RPM to increase with the TCC locked up? I’ve got other vehicles with cylinder deactivation as well and I’ve never seen this.

 

[wsteele]

Since there’s no DIC in the SSV, is there any other telltale of four cylinder operation? Short of driving around with a scan tool or something? I have not detected any difference in engine sound etc to clue me in that it’s engaged.

I don’t have a real need to know, I suppose, I’m just curious about all things that affect fuel consumption and engine life.

Under what conditions are you guys with indicators seeing it operate? I had a Colorado V6 ZR2 that only used V4 mode between about 25 - 35 mph. Why bother? SMH
I also have a full-size Ram that’ll do V4 up to around 55 mph steady cruising.

Put me in the "insensitive male" types (my wife would concur with this diagnosis), as the only way I know my Yukon is in V4 is when I have that page up on the DIC.

It is seamless and undetectable to me otherwise. On my rig, V4 only is engaged when I lift slightly on the throttle or the grade changes enough for load to be reduced. Also, it only engages if I am in 3rd or 4th gear when the above conditions are met (i.e. if in 1-2 gear, lifting off the throttle doesn't engage V4, I only learned the above when I was testing Tow Mode and how it affected the AFM, as Tow Mode runs the RPM's up a lot higher before shifting, hence no shift to third below like 30 mph, leading me to believe Tow Mode disengages AFM, which it doesn't).

 

[HeidiHoe]

How is it possible for the RPM to increase with the TCC locked up? I’ve got other vehicles with cylinder deactivation as well and I’ve never seen this.

Not a huge rpm jump, 100ish, computer controlled/drive-by-wire can make that happen. Its barely discernible and you have to be watching for it.

 

[Bill 1960]

Not a huge rpm jump, 100ish, computer controlled/drive-by-wire can make that happen. Its barely discernible and you have to be watching for it.

Sorry, but I’m going to have to disagree. Electronics might make a glitch in the tach. There’s no way it’s going to magically change the transmission ratio so that it’ll run for example 1500 RPM on 8 cylinders and 1600 on 4. At a fixed speed.
Unlocking the TCC could do it, but that certainly wouldn’t improve fuel economy.
More likely just some glitchy data on the bus to the cluster from a bad ground or voltage spike.

 

[2011SSVHOE]

You just can't beat a DIC.

 

[BG1988]

Put me in the "insensitive male" types (my wife would concur with this diagnosis), as the only way I know my Yukon is in V4 is when I have that page up on the DIC.

It is seamless and undetectable to me otherwise. On my rig, V4 only is engaged when I lift slightly on the throttle or the grade changes enough for load to be reduced. Also, it only engages if I am in 3rd or 4th gear when the above conditions are met (i.e. if in 1-2 gear, lifting off the throttle doesn't engage V4, I only learned the above when I was testing Tow Mode and how it affected the AFM, as Tow Mode runs the RPM's up a lot higher before shifting, hence no shift to third below like 30 mph, leading me to believe Tow Mode disengages AFM, which it doesn't).

Tow mode in 3rd disables AFM


unless you have a hybrid which is disabled in all gears i.e using M4... this also disables the overdrive gear i.e 5th "Sun gear" though
(aka EVT)

 

[wsteele]

Tow mode in 3rd disables AFM


unless you have a hybrid which is disabled in all gears i.e using M4... this also disables the overdrive gear i.e 5th "Sun gear" though
(aka EVT)

No, AFM is unaffected by tow mode, at least in a 2007 Yukon SLT.

 

[BG1988]

No, AFM is unaffected by tow mode, at least in a 2007 Yukon SLT.

it should disable when shifted to the number 3 on the steering column..

 

[wsteele]

it should disable when shifted to the number 3 on the steering column..

Right, but that isn’t affected by tow mode. That was the point I was making.

Manual shifting through the gears does disable AFM, as long as you stop before you get to D.

Seems like a pretty difficult way to avoid AFM, at least if you are shifting on a column.