Awful gas mileage...

strafingmoose · February 2, 2012

Hi all

Here I have a 2007, 4.8L, RWD with the 3.23 gears and winter tires on (245/70/R17)

So, yeah, my gas mileage sucks. I know we're in (cold) winter, but it wasn't that bad with my 2003 (with the same specs).

With the 2003, I'd get 15mpg or close to that in winter. Now, hold on to your hat, the 2007 does something like 9-10.

I find that pretty awful and will take it in the dealership next week.

Truck runs great, I don't get it. What do you guys think ? Any specific issues with the 2007 NBS ?

Thanks.

tesnoboy · February 2, 2012

Oxygen sensors going bad can cause a drop in fuel mileage and not set a code til they completely fail. I have noticed that the new Winter blend gas does suck and reduces mileage. These emission nuts do exactly the opposite of what they think they are doing with their damn special gas blends. You end up using more gas!

strafingmoose · February 2, 2012

Yeah, I heard they throw in more ethanol in the mix during winter. Also the legitimate components you'd want in a gas mix (ie: the ones that allows your truck to start smoothly even @ -10F) reduce gas mileage, but 10MPG ?! Give me a break.

pm26 · February 2, 2012

You have a 2WD with very tall gearing. I agree that this gas mileage is too low, unless you floor the truck from every stoplight. I would expect 12-14 MPG city even with E85, which lowers fuel economy by about 20%. with E10 you should see at least 14-15 MPG. Try running some Cehvron Techron injector cleaner through and see if the mileage improves.

Tall gears actually hurt your city fuel economy.

Stevens03 · February 2, 2012

My mileage is much better than that. Somethings wrong. Do you have remote start and are you using it more, or have you check the tire pressure to make sure its optimum? Winter "blend" will cause 1-2mpg drop, at least thats what I see but 9-10 is horrible. Have you checked the obvious like air filter, cleaned your maf sensor, cleaned your throttle body, tune up if necessary?

strafingmoose · February 2, 2012

Yeah, I think 3.4x are more balanced, but hey, that was the deal I could get my hands on. Plus, 3.23 don't have the G80 locker

I'm going to have the dealership doing all that check up.

pm26 · February 2, 2012

A dragging brake caliper can have a bad effect on fuel eonomy as well.

strafingmoose · February 2, 2012

Brakes do squeak alot but the dealership told me it's because the previous owner installed cheap ass parts, apparently, nothing was really wrong with them.

AirForceAngler · February 2, 2012

Brakes do squeak alot but the dealership told me it's because the previous owner installed cheap ass parts, apparently, nothing was really wrong with them.

Why were new brakes put on a 2007 already? How many miles are on it? Maybe something is dragging that caused them to wear out? Since it's a 4.8, I doubt it was used for much heavy duty towing that would wear the brakes out quicker. It's nothing for a well driven Chevy truck to go into the 6 figure mileage marks with original brakes.

strafingmoose · February 2, 2012

Brakes do squeak alot but the dealership told me it's because the previous owner installed cheap ass parts, apparently, nothing was really wrong with them.

Why were new brakes put on a 2007 already? How many miles are on it? Maybe something is dragging that caused them to wear out? Since it's a 4.8, I doubt it was used for much heavy duty towing that would wear the brakes out quicker. It's nothing for a well driven Chevy truck to go into the 6 figure mileage marks with original brakes.

The new brakes were put on when I bought it. Actually, only the pads or discs were changed. Can't remember. But dealer inspected them afterwards (when I reported the squeaking issue) and they said they were fine, just low quality. Truck had about 25,000 miles when I bought it so I'd say normal wear. Plus, previous owner used it as a car, not as a truck.

Silverado4x4 · February 2, 2012

Alot of people dont take into account the idle time warming the truck up in the morning or when ever, this will kill your mpg per tank, fuel being burned and the truck not moving.

Mckenzie · February 2, 2012

My 01 with 33's will do 15 on the i state and prolly 11-12ish in stop and go now keep in mind its got 203K miles on it and a heavy ass brushguard and tool box and random shit in the backs seat

jdubub · February 3, 2012

Alot of people dont take into account the idle time warming the truck up in the morning or when ever, this will kill your mpg per tank, fuel being burned and the truck not moving.

+1. I noticed the slightest amount of time just idling lowers the avg mpg big time. Whether it's from sitting at long stop lights, just sitting in the truck, or warming it up in the morning

SparkySparks · February 3, 2012

Between winter gas and the fact that my normal commute went from about 15 minutes if I hit every light to about 30 minutes with the longer waits at light due to road work, my mpg is down about 3-4mpg lower then normal. I remember when I lived up north I didn't really pay much attention to my mpgs during the winter cause I would leave the engine running longer in the morning to warm up.

Big Whiskey · February 3, 2012

I'm wondering about the injectors or a dragging brake too. 9-10 mpg is waaaaay too low...even in winter. Something is wrong. I've got 10-ply 285/70/17 tires...use the remote start all the time...and drive like a wild man most mornings because I'm late for work....and my DIC average is still over 14 mpg....with the 6.0. Your 4.8 should be at least that.