Rarley goes to V4

[outrage231]

Hey Everyone,

I just got a brand new 2007 LTZ. This thing eats gas like its going out of style. My average is 14 mpg. I rarely see the truck go into V4 mode. The only time does goes in V4 mode is when I take my foot off the gas. Other than that its V8 most of the time. Is this normal?

Thanks.

 

[JRTV8]

Can't say if its normal or not normal but what I have read and been told the V4/ Active Fuel Management System kicks in when less power is needed most of time in highways.

 

[Andy4639]

From driving mine now for 16000 miles it will kick in after you have a steady foot on level ground or coasting.
I get anywhere from 18,20 with unleaded regular, if you are using the E-85 fuel then your gas milage is about right.

 

[outrage231]

From driving mine now for 16000 miles it will kick in after you have a steady foot on level ground or coasting.
I get anywhere from 18,20 with unleaded regular, if you are using the E-85 fuel then your gas milage is about right.

Nope using unleaded. I only have about 600 miles on it. Even if I put the cruise control 65 mph on the highway it still only gives me 14.5 to 16 avg. No V4 unless I am going down hill. Ahh just my luck I guess. These rising gas prices sure don't help.

 

[JRTV8]

Nope using unleaded. I only have about 600 miles on it. Even if I put the cruise control 65 mph on the highway it still only gives me 14.5 to 16 avg. No V4 unless I am going down hill. Ahh just my luck I guess. These rising gas prices sure don't help.

Hmmm .. wow this is strange...

 

[LAP TOP GAMER]

Hmmm .. wow this is strange...

Take into consideration that @ 600 mile the engine is tight with lots of internal friction, and needs to be broken in, that would account for lower mileage as well.

 

[JRTV8]

That's a possibility!!!

 

[LAP TOP GAMER]

The active management works best when the cruise control is set for highway cruising on a flat straightaway, other than it is dips in and out of that mode. I never bought it for stellar gas millage in the first place. I bought because(1) quality(2)features(3) flex fuel(4)On star(5) its a Chevy(6) it looks so dam good. I expect to get about 300,000 miles out of it, yes I am one of those weird people that keep a good vehicle for a long time.:Chevy: :Chevy: :Chevy: :Chevy: :Chevy: :Chevy: :Chevy:

 

[Andy4639]

If you plan to keep it for a long time then don't use the E-85 in it much. I have used four tanks of the crap and want ever put it in again except maybe for riding around home never for a trip on the interstate. That stuff sucks.
Unlead Regular=18 to 20
E-85 = 12 to 14
This was 5 hr driving to our beach house each way. I tried it and that's it.

 

[bparker]

Take into consideration that @ 600 mile the engine is tight with lots of internal friction, and needs to be broken in, that would account for lower mileage as well.

:iagree: :withstupid:

 

[Andy4639]

600 miles

I agree that the milage should go up on the truck after break in. But I also think it's not going to go up that much. I would bet you need the computer reset at the dealer. Have you done the math yourself or just using the dash computer?
My average was crap when done by the dash, but doing it myself it was a lot better.

 

[73shark]

The consensus I've seen from several other Tahoe forums is that mpg continues to improve up to about 7,500 mi and that the 4:10 axle ratio gets better mpg than the 3:73 because the 5.3 is operating in it'd "sweet spot" more with the 4:10.(I know that this is counterintuitive) The V4 mode also works better with the 4:10 for the same reason. I'm at about 5,500 mi and getting 14 in town now. Switching to Mobil 1 at the first oil change got me about a 0.5 mpg improvement.

I've got the 3:73 and have yet to see V4 on flat hiway at 60-75 mph. I have induced V4 in town on slight inclines by putting it in tow mode which at those speeds (30-45) takes it out of OD. Improves mpg by about 3-4 mpg. That doesn't work at hwy speeds tho.

Let's face it. If you want good mileage, you aren't going to get it hauling 2.5 tons of American iron. atriot:
:Chevy:

:thumbsup:

 

[Andy4639]

Gas MPG

I couldn't agree more. If you are wanting a milage SUV this ant the one you want. If you want the best looking SUV then it is for sure! Hands Down!

 

[dcovell]

For those with the 5.3 what is the optimal RPM range for peak torque? It seems that you would want the gearing to put the RPMs while going about 65-70 in that range. Also with an aftermarket air filter and a cat-back (from my experience with Ford products) it moves that range a bit)

 

[Andy4639]

Interstate RPM'S

Driving home today at 70-75 MPH I was running about 2200RPM'S.
This is with a strong head wind too! 3.73 rear end gear in overdrive.

 

[JRTV8]

Driving home today at 70-75 MPH I was running about 2200RPM'S.
This is with a strong head wind too! 3.73 rear end gear in overdrive.

I don't know but to me that sounds pretty good heading against wind especially dealing with drag. :yesnod:

 

[dcovell]

According to some dynos I have seen for the 5.3 (about 2004). The peak horse power is at about 5,300 RPMs and the peak torque is at about 3,300 RPMs.

For the 5.3 in the 2007 year, the specs from GMs site list the peak horsepower at 320HP at 5,200 RPMs and 340 ft/lb of torque at 4,200 RPMs. The 5.3 in 2007 GM kicked up the power output of the 5.3, looks like they moved the RPMs up a bit.

So really the tourque is much higher than say my Ford truck (2001) that is down at around 2,600 RPMs. This means that you do want the highest gears possible so you can get reasonabily close to the 4,200 RPMs

Compared to Ford:
Ford 5.4 (04-current)
Horsepower 300@5,000 RPMs
Torque 365@3,750 RPMs

Ford 5.4 (99-04)
Horsepower 260@4,500 RPMs
Torque 350@2,500 RPMs

 

[dcovell]

Hey amgv8400 did the active fuel management kick in on that trip?

 

[JRTV8]

Hey amgv8400 did the active fuel management kick in on that trip?

I was referring to Andy's message

 

[dcovell]

Sorry, my bad.... ANDY was the active fuel management on anytime during that trip?