Hi Rob
I have notced also on long distance driving that constant foot pressure maintained will get you into V$ however staying there is a challenge, if the grade of the road changes she instantly will come out of V4. Also while in V4 mode I have noticed when coming into and out of Hybrid mode, sometimes the engine will switch from V4 to V8. Also the condition of the road very bumpy etc will bounce you out of V4 mode. To date the modifications I have completed have not effected the V4 mode, ie an increase or ease.

 

I wish there was a manual switch that one can Use to switch to v4 if no power is needed, and then back to v8 for more power. This would save a lot of gas for sure, but I don't think it can be easily implemented.
Same thing for EV mode.
Any feed back from the experts on this issue Would be interesting to know why it can't be implimened

 

here is the conditions when the V4 is deactivated to work back to a V8 mode. note that the ECU detects if there is detonation. it means that you really have to put it premium fuel to maximize this function.


Engine coolant temperature out of range for cylinder activation
Engine vacuum out of range
Brake booster vacuum out of range
Transmission gear incorrect or shift in progress
Accelerator pedal out of range or rate of pedal application too fast
Engine oil pressure and temperature out of range
Engine speed out of range
Vehicle speed out of range
Minimum time in V8 mode not met
Maximum V4 mode time exceeded
Decel fuel cutoff active
Reduced engine power active
Torque management active
Catalytic converter over temperature protection active
Piston protection active, knock detected
Cylinder deactivation solenoid driver circuit faults

 

got this from the service manual of alldata

 

THanks Evios,
Very informative

 

All; about V4. I strongly urge any of you who can to drive a non-hybrid Tahoe, Yukon, Escalade, or Silvarado. The hybrid goes into V4 and stays there considerably longer than the non-hybrids. My personal experience is that about half my driving is in V4 and I have never run premium. I have a real hard time in non hybrid even getting V4, except on a down hill.

The 6.0L has more V4 displacement than the 5.3L but the electric boost from storage is the real reason you can drive so much more V4 time.

V4 will usually drop back to V8 at the onset of perceptable noise or harshness. The guys that have removed the resonators and installed non-factory inductions can probably hear a pretty good moan or Jake Brake type sound just before V4 goes back to V8.

 

Hillbilly Update: I'm in Colorado skiing. I brought a 2008 Yukon that turned 100,000 miles before I left Michigan. I got 21.6 mpg Detroit to Davenport Iowa over the first 450 miles. Then as I-80 starts the climb from about 900 ft to 5000 in Denver I bucked a 35 mph plus head wind the whole way. I ran posted speed plus 4 so my Nebraska to Colorado FE took a severe hit. 79 mph into that unrelenting gust put a hurt on me but I was on a mission to make Good Friday dinner at my sisters in Denver.

Saturday we ran to Vail over two snow covered passes. Running up hill in 4 high at 65. Not so good FE. Sunday A Basin. Today we took a break and went down to Evergreen and back to Breckenridge shopping. My long term FE has recovered to 19.8 from 19,6 on that up hill run. I slowed down and the roads cleared up. I think my Nebraska leg was low 18's.

I am logging my speeds and conditions round trip. Will post. I want that tail wind going back.

 

Marty,
Sounds like a great trip, I like Vail Beaver Creek Especially, good friends there.