O7 Avalanche

rockhawk · 03-17-2007, 09:11 AM

Dear GM/Chevy,
I have 4500 miles on my 07 Avalanche 4X4 Z71 purchased in 12/06. This is my 3rd Avalanche. I have previously owned and 02, 04, 05. I still live in the same place so my driving habits have not changed. I have logged over 75k miles combined in the above-mentioned vehicles. I have always gotten 17+ MPG on the hiway @ 70+MPH and averaged 15 MPG in town. This new truck is a complete gas hog. I am barely averaging 15 combined. I noticed that this new vehicle runs at 500 RPM higher at the same speeds as the older models. How can this help the gas mileage. What can be done to adjust or tweak this new engine to improve the mileage. This is unacceptable and poor engineering on Chev part. Yes the rearends are all the same 393. I already checked to make sure. None were 410's. Funny how the Jeep Hemi with a larger engine gets double the MPG on their 4/8 cylinder vehicles. Must be Mercedes Benz engineering influence. I am very unhappy with the mileage. I love the vehicle though. Help!

AndrewGS · 03-17-2007, 09:26 AM

Quote:

Originally Posted by rockhawk

Dear GM/Chevy,
I have 4500 miles on my 07 Avalanche 4X4 Z71 purchased in 12/06. This is my 3rd Avalanche. I have previously owned and 02, 04, 05. I still live in the same place so my driving habits have not changed. I have logged over 75k miles combined in the above-mentioned vehicles. I have always gotten 17+ MPG on the hiway @ 70+MPH and averaged 15 MPG in town. This new truck is a complete gas hog. I am barely averaging 15 combined. I noticed that this new vehicle runs at 500 RPM higher at the same speeds as the older models. How can this help the gas mileage. What can be done to adjust or tweak this new engine to improve the mileage. This is unacceptable and poor engineering on Chev part. Yes the rearends are all the same 393. I already checked to make sure. None were 410's. Funny how the Jeep Hemi with a larger engine gets double the MPG on their 4/8 cylinder vehicles. Must be Mercedes Benz engineering influence. I am very unhappy with the mileage. I love the vehicle though. Help!

GM doesn't do 3.93 gearing. Please, post any HEMI-equipped vehicle getting DOUBLE the mileage. GM has AFM to run on four cylinders when eight aren't needed and the Avalanche has it.

MelvinJ · 03-17-2007, 10:25 AM

If you are really running 500 rpms more at the same speeds with the same rear end gears and roughly the same tire diameter, then I would suspect your torque converter isn't locking up. I mean, what else could possibly account for a difference like that? They haven't changed the ratios of the transmission. This would certainly account for your decrease in mileage.

If I were you, I would go to the dealer, take out a used 2005 or 2006 Avalanche with the same gearing and have the dealer verify how many rpms are turning at 70. Then take yours out and check rpms at 70, and demand an explanation for the 500 rpm difference. Don't accept 'that's just how they run' or anything else like that. They should be able to explain the difference specifically. Make sure they check the lock up on the torque converter.

ctaylorzl1 · 03-17-2007, 04:41 PM

The only 2 axle ratios are 3.73 & 4.10, so I assume it has the 3.73, and since you are using the same old 4-speed tranny you have in previous Avalanches you have the same .63 4th gear ratio. I dont really see how you could be reving 500rpms more. Unless you are running a smaller tire, but the factory 265/18 should have the same profile as previous Avalanches. And also if you do have a 07 then you have AFM(cyl deactivation). So I think you need to talk to your dealer about this. My GPA has a 07 Avalanche similarly equiped as yours(not Z71 though)and he averages between 17 & 18! Also, My neighbor has a new HEMI Durango with MDE and he complains of gaveraging 14 or 15mpg, very nice SUV though.

RamJet502 · 03-17-2007, 04:48 PM

Quote:

Originally Posted by rockhawk

This new truck is a complete gas hog. I am barely averaging 15 combined.

A big heavy SUV is going to get that kind of gas mileage in real world driving, not much that can be done about it.

likearock00 · 03-17-2007, 04:58 PM

What about the weight of the vehicle? With the new design, did they add a few extra lbs to make the truck work harder? This is very odd. Do you have the a/c on or off comparing the 2? I always make sure my a/c is off- check to see if you have a snowflake on the temp display. That's all I can think of...

aka_Matt · 03-17-2007, 08:09 PM

u say u owned 3 avalanches, yet u say u had an '02, '04, and '05, that makes this one your 4th... just curious, y did u get rid of them so fast/soon, when they didn't have many miles on them?

TuffG929 · 03-17-2007, 08:47 PM

Quote:

Originally Posted by rockhawk

Dear GM/Chevy,
I have 4500 miles on my 07 Avalanche 4X4 Z71 purchased in 12/06. This is my 3rd Avalanche. I have previously owned and 02, 04, 05. I still live in the same place so my driving habits have not changed. I have logged over 75k miles combined in the above-mentioned vehicles. I have always gotten 17+ MPG on the hiway @ 70+MPH and averaged 15 MPG in town. This new truck is a complete gas hog. I am barely averaging 15 combined. I noticed that this new vehicle runs at 500 RPM higher at the same speeds as the older models. How can this help the gas mileage. What can be done to adjust or tweak this new engine to improve the mileage. This is unacceptable and poor engineering on Chev part. Yes the rearends are all the same 393. I already checked to make sure. None were 410's. Funny how the Jeep Hemi with a larger engine gets double the MPG on their 4/8 cylinder vehicles. Must be Mercedes Benz engineering influence. I am very unhappy with the mileage. I love the vehicle though. Help!

Have you been using the remote start feature?

1BadPig · 03-18-2007, 05:43 AM

Doesn't the mileage improve with usage? After all you've only got 4500 miles on it.

05ChevySilveradoSS · 03-19-2007, 09:09 AM

Quote:

Originally Posted by AndrewGS

GM doesn't do 3.93 gearing. Please, post any HEMI-equipped vehicle getting DOUBLE the mileage. GM has AFM to run on four cylinders when eight aren't needed and the Avalanche has it.

Makes Me Wonder If He Really Owns An Avalanche. Ive Driven Them (Many Of Them), And They Get Pretty Good Combined Mpg. And Yes With 3.73, And The Vortec 5.3.

darndot · 03-19-2007, 09:27 AM

Quote:

Originally Posted by 1BadPig

Doesn't the mileage improve with usage? After all you've only got 4500 miles on it.

It should improve with usage.

My question is have you talked with your dealership's shop about it?

LIKAROK · 04-10-2007, 09:51 PM

Quote:

Originally Posted by 1BadPig

Doesn't the mileage improve with usage? After all you've only got 4500 miles on it.

Totally agree. Any Silverado pick-up I have ever had never starts getting decent mileage til it has at least 8000 to 10000 Km on it.

03-17-2007, 09:11 AM	#1 (permalink)
rockhawk Walking Join Date: Mar 2007 Posts: 1	O7 Avalanche Dear GM/Chevy, I have 4500 miles on my 07 Avalanche 4X4 Z71 purchased in 12/06. This is my 3rd Avalanche. I have previously owned and 02, 04, 05. I still live in the same place so my driving habits have not changed. I have logged over 75k miles combined in the above-mentioned vehicles. I have always gotten 17+ MPG on the hiway @ 70+MPH and averaged 15 MPG in town. This new truck is a complete gas hog. I am barely averaging 15 combined. I noticed that this new vehicle runs at 500 RPM higher at the same speeds as the older models. How can this help the gas mileage. What can be done to adjust or tweak this new engine to improve the mileage. This is unacceptable and poor engineering on Chev part. Yes the rearends are all the same 393. I already checked to make sure. None were 410's. Funny how the Jeep Hemi with a larger engine gets double the MPG on their 4/8 cylinder vehicles. Must be Mercedes Benz engineering influence. I am very unhappy with the mileage. I love the vehicle though. Help!

03-17-2007, 10:25 AM	#3 (permalink)
MelvinJ 5.3 Liter LS4 V8 Join Date: Nov 2003 Posts: 3,653	Re: O7 Avalanche If you are really running 500 rpms more at the same speeds with the same rear end gears and roughly the same tire diameter, then I would suspect your torque converter isn't locking up. I mean, what else could possibly account for a difference like that? They haven't changed the ratios of the transmission. This would certainly account for your decrease in mileage. If I were you, I would go to the dealer, take out a used 2005 or 2006 Avalanche with the same gearing and have the dealer verify how many rpms are turning at 70. Then take yours out and check rpms at 70, and demand an explanation for the 500 rpm difference. Don't accept 'that's just how they run' or anything else like that. They should be able to explain the difference specifically. Make sure they check the lock up on the torque converter.

03-17-2007, 04:41 PM	#4 (permalink)
ctaylorzl1 5.3 Liter LS4 V8 Join Date: Nov 2005 Location: Indiana Drives: 1996 Dodge 3500 CTD 4x4 1992 Camaro RS 305 Posts: 3,303	Re: O7 Avalanche The only 2 axle ratios are 3.73 & 4.10, so I assume it has the 3.73, and since you are using the same old 4-speed tranny you have in previous Avalanches you have the same .63 4th gear ratio. I dont really see how you could be reving 500rpms more. Unless you are running a smaller tire, but the factory 265/18 should have the same profile as previous Avalanches. And also if you do have a 07 then you have AFM(cyl deactivation). So I think you need to talk to your dealer about this. My GPA has a 07 Avalanche similarly equiped as yours(not Z71 though)and he averages between 17 & 18! Also, My neighbor has a new HEMI Durango with MDE and he complains of gaveraging 14 or 15mpg, very nice SUV though. __________________ Last edited by ctaylorzl1 : 03-17-2007 at 04:44 PM.

03-17-2007, 04:58 PM	#6 (permalink)
likearock00 7.0 Liter LS7 V8 Join Date: Aug 2005 Location: NC Drives: 2006 Chevy Silverado Crew Cab Z-71 Posts: 7,624	Re: O7 Avalanche What about the weight of the vehicle? With the new design, did they add a few extra lbs to make the truck work harder? This is very odd. Do you have the a/c on or off comparing the 2? I always make sure my a/c is off- check to see if you have a snowflake on the temp display. That's all I can think of... __________________ "You can fool some of the people all the time, and those are the ones you want to concentrate on." -George W. Bush

03-17-2007, 08:09 PM	#7 (permalink)
aka_Matt Walking Join Date: Dec 2003 Posts: 13	Re: O7 Avalanche u say u owned 3 avalanches, yet u say u had an '02, '04, and '05, that makes this one your 4th... just curious, y did u get rid of them so fast/soon, when they didn't have many miles on them?

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03-18-2007, 05:43 AM	#9 (permalink)
1BadPig 4.4 Liter Supercharged Northstar Join Date: Sep 2004 Location: Florida Posts: 2,055	Re: O7 Avalanche Doesn't the mileage improve with usage? After all you've only got 4500 miles on it. __________________ Current Rides 2006 Chevrolet HHR 1LT Sunburst Orange Metallic 2007 Chevrolet Tahoe LT3 Gold Mist Metallic

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