poor gas mileage

wrote in message

> On Dec 13, 9:55 pm, "Ed H." wrote:
>> "Picasso" wrote in message
>>
>>
>>
>> >> I have a 99 Silvy 4wd with the 5.3l and I get better milage then that,
>> >> around 15 in town, BUT you have a crew cab and it wieghts more then
>> >> the ext cab, plus I don't think the 05 is areodynamic. Isn't this the
>> >> timeframe when they started changing the body style to the squared off
>> >> front end again? When is the last time you had a service performed?
>> >> That is going to hurt you some, dirty filter, etc..
>>
>> > what hte heck do you mean "Service"....
>> > You can service whatever you want and not gain 10mpg
>>
>> I'm not sure I follow your statement. The OP is asking about a
>> difference
>> of 37% max (290 miles vs. 400 miles on a 26 gallon tank), not the almost
>> 100% increase you suggest with a 10 mpg gain. Of course it would be
>> helpful
>> to know what the actual MPG is, rather than the range on a "tank" of gas.
>>
>> To , have you calculated your actual MPG, of do you
>> just fill up when the gas gauge indicates you are low and compare how far
>> you have driven since the last fill up? It may be something as simple as
>> the gauge indicates low when you have several gallons left. From your
>> post
>> of MPH vs. RPM it sounds like your OD may not be engaging, which I don't
>> think would account for the kind of MPG loss you claim, but real world
>> MPG
>> numbers may tell a different story.
>
> Also, when I press the overdrive button, the enginge does not increase
> in rpms like my old ford. A Gm mechanic said that is perfectly normal
> for it to not increase rpms. But I don't know.How many gears should I
> go through before i hit overdrive?

First off, This is a Chevy and not a Ford so you're not hitting an
"overdrive" button on the end of the shifter - it's the "tow/haul mode"
button if just clicked once quickly. And No, it won't change your RPM's
because all it does is change the shift points between gears as you
accelerate and run up through them to finally arrive at overdrive.

If you really want to disable your overdrive, press and HOLD the tow/haul
button - but be prepared to see a sharp rise in RPM's when you do (I don't
suggest doing at highway speeds). At that point you should also see a light
on your dash with OD and a line through it indicating that the overdrive is
disabled.

I can't say if 2200 rpm is too high or just right - my Silverado is a 2500HD
with the Duramax and Allison so what I get won't be comparable to what you
should get. However, I get 500 miles on a complete 26 gallon tank of
diesel - or I did before I went to larger tires. I have a speedo error now
and haven't remeasured it. There are three things to check when you see
mileage like yours: 1) a basic tune up with plugs, air filter, fuel filter,
pcv valve, etc. 2) make sure your torque converter is locking up at highway
speeds; and 3) check your rear axle ratio. If you have a 4.10:1 rear axle
for towing then you are getting the mileage I would expect to see. But if
you have a 3.73 or lower ratio then you've got an issue here.

To check if you torque converter is locking up properly, you can drive along
at a steady 50mph on flat terrain (the converter should be locked up at this
point). With your right foot still on the gas, use your left foot and
lightly press your brake pedal - not firm enough to slow you down but just
enough to activate the brake lights. You should see a 200-300 jump in RPM
indicating that the converter is unlocking. If you don't see the jump then
it may not be locked up to begin with.

Cheers - Jonathan
 >> Stay informed about: poor gas mileage 

"Picasso" wrote in message

>> I have a 99 Silvy 4wd with the 5.3l and I get better milage then that,
>> around 15 in town, BUT you have a crew cab and it wieghts more then
>> the ext cab, plus I don't think the 05 is areodynamic. Isn't this the
>> timeframe when they started changing the body style to the squared off
>> front end again? When is the last time you had a service performed?
>> That is going to hurt you some, dirty filter, etc..
>
> what hte heck do you mean "Service"....
> You can service whatever you want and not gain 10mpg

I'm not sure I follow your statement. The OP is asking about a difference
of 37% max (290 miles vs. 400 miles on a 26 gallon tank), not the almost
100% increase you suggest with a 10 mpg gain. Of course it would be helpful
to know what the actual MPG is, rather than the range on a "tank" of gas.

To , have you calculated your actual MPG, of do you
just fill up when the gas gauge indicates you are low and compare how far
you have driven since the last fill up? It may be something as simple as
the gauge indicates low when you have several gallons left. From your post
of MPH vs. RPM it sounds like your OD may not be engaging, which I don't
think would account for the kind of MPG loss you claim, but real world MPG
numbers may tell a different story.
 >> Stay informed about: poor gas mileage 

On Dec 13, 10:25 pm, wrote:
> On Dec 13, 9:55 pm, "Ed H." wrote:
>
>
>
>
>
> > "Picasso" wrote in message
>
> >
>
> > >> I have a 99 Silvy 4wd with the 5.3l and I get better milage then that,
> > >> around 15 in town, BUT you have a crew cab and it wieghts more then
> > >> the ext cab, plus I don't think the 05 is areodynamic. Isn't this the
> > >> timeframe when they started changing the body style to the squared off
> > >> front end again? When is the last time you had a service performed?
> > >> That is going to hurt you some, dirty filter, etc..
>
> > > what hte heck do you mean "Service"....
> > > You can service whatever you want and not gain 10mpg
>
> > I'm not sure I follow your statement. The OP is asking about a difference
> > of 37% max (290 miles vs. 400 miles on a 26 gallon tank), not the almost
> > 100% increase you suggest with a 10 mpg gain. Of course it would be helpful
> > to know what the actual MPG is, rather than the range on a "tank" of gas.
>
> > To , have you calculated your actual MPG, of do you
> > just fill up when the gas gauge indicates you are low and compare how far
> > you have driven since the last fill up? It may be something as simple as
> > the gauge indicates low when you have several gallons left. From your post
> > of MPH vs. RPM it sounds like your OD may not be engaging, which I don't
> > think would account for the kind of MPG loss you claim, but real world MPG
> > numbers may tell a different story.
>
> Also, when I press the overdrive button, the enginge does not increase
> in rpms like my old ford. A Gm mechanic said that is perfectly normal
> for it to not increase rpms. But I don't know.How many gears should I
> go through before i hit overdrive?- Hide quoted text -
>
> - Show quoted text -

Your fuel tank is a 26 gallon tank, you have a 5.3l 1500 crew cab, 4
wheel drive. The 2008 version is EPA rated at 14 city, 19 highway.

You have not told us what rear gear you have, you have not told us
your driving habits (all city, all highway, mix), you do say you have
a light foot. You have not told us at what point you fill up,
completely empty, 1/4 tank etc. So this is the best you are going to
get for an answer.

A 26 gallon tank at 290 miles is approximately 11.5 MPG, so yes, you
seem to be a little off from what it should be.

As a comparision, with mine, with the only differences being year and
that I have the extended cab, I am getting around 350 in the city,
which puts me closer to the EPA rating.
 >> Stay informed about: poor gas mileage 

On Dec 14, 9:11 am, azwiley1 wrote:
> On Dec 13, 10:25 pm, wrote:
>
>
>
>
>
> > On Dec 13, 9:55 pm, "Ed H." wrote:
>
> > > "Picasso" wrote in message
>
> > >
>
> > > >> I have a 99 Silvy 4wd with the 5.3l and I get better milage then that,
> > > >> around 15 in town, BUT you have a crew cab and it wieghts more then
> > > >> the ext cab, plus I don't think the 05 is areodynamic. Isn't this the
> > > >> timeframe when they started changing the body style to the squared off
> > > >> front end again? When is the last time you had a service performed?
> > > >> That is going to hurt you some, dirty filter, etc..
>
> > > > what hte heck do you mean "Service"....
> > > > You can service whatever you want and not gain 10mpg
>
> > > I'm not sure I follow your statement. The OP is asking about a difference
> > > of 37% max (290 miles vs. 400 miles on a 26 gallon tank), not the almost
> > > 100% increase you suggest with a 10 mpg gain. Of course it would be helpful
> > > to know what the actual MPG is, rather than the range on a "tank" of gas.
>
> > > To , have you calculated your actual MPG, of do you
> > > just fill up when the gas gauge indicates you are low and compare how far
> > > you have driven since the last fill up? It may be something as simple as
> > > the gauge indicates low when you have several gallons left. From your post
> > > of MPH vs. RPM it sounds like your OD may not be engaging, which I don't
> > > think would account for the kind of MPG loss you claim, but real world MPG
> > > numbers may tell a different story.
>
> > Also, when I press the overdrive button, the enginge does not increase
> > in rpms like my old ford. A Gm mechanic said that is perfectly normal
> > for it to not increase rpms. But I don't know.How many gears should I
> > go through before i hit overdrive?- Hide quoted text -
>
> > - Show quoted text -
>
> Your fuel tank is a 26 gallon tank, you have a 5.3l 1500 crew cab, 4
> wheel drive. The 2008 version is EPA rated at 14 city, 19 highway.
>
> You have not told us what rear gear you have, you have not told us
> your driving habits (all city, all highway, mix), you do say you have
> a light foot. You have not told us at what point you fill up,
> completely empty, 1/4 tank etc. So this is the best you are going to
> get for an answer.
>
> A 26 gallon tank at 290 miles is approximately 11.5 MPG, so yes, you
> seem to be a little off from what it should be.
>
> As a comparision, with mine, with the only differences being year and
> that I have the extended cab, I am getting around 350 in the city,
> which puts me closer to the EPA rating.- Hide quoted text -
>
> - Show quoted text -

I fill up when the light comes on and the miles are city and highway.
I do not know what gears I have. How can I find that out ?
 >> Stay informed about: poor gas mileage 

wrote:

>
> Also, when I press the overdrive button, the enginge does not increase
> in rpms like my old ford. A Gm mechanic said that is perfectly normal
> for it to not increase rpms. But I don't know.How many gears should I
> go through before i hit overdrive?

Me thinks this is your problem, there is no overdrive button. OD is another
notch on the shift lever, the button is two/haul mode. If your running
around in tow/haul mode that could account for the low mpg.
 >> Stay informed about: poor gas mileage 

Bill wrote:

> I'd bet the 4wd gears are what is hurting you.
> I had a 5.3l with 3.43 gears, and 70mph was 1750 to 1800 rpm.
> 2000 rpm was closer to 80.
> I was getting closer to 20 to 21 mpg.
>
>
Mine is 4wd and I can get 19-20. 4wd makes very little difference anymore.
 >> Stay informed about: poor gas mileage 

Since you can't tell what gear you are, why don't you redneck it.
The stick on the column, put it in 1st, go, then 2nd, go, than 3rd, go, than
D, than go some more.
You should see something happen on your tach.
That will tell you if your tranny still had OD.



wrote in message

>I have a 2005 gmc crew cab z71. I have a 26 gallon tank and I am only
> getting 290 miles off of a tank of gas is this right? I know other
> guys who are getting 350 to 400 miles off of their tanks. I checked
> air filter and most common things. I have 60k miles on the truck and I
> drive with a light foot. Thanks
 >> Stay informed about: poor gas mileage 

wrote in message

> On Dec 14, 9:11 am, azwiley1 wrote:
>> On Dec 13, 10:25 pm, wrote:
>>
>>
>>
>>
>>
>> > On Dec 13, 9:55 pm, "Ed H." wrote:
>>
>> > > "Picasso" wrote in message
>>
>> > >
>>
>> > > >> I have a 99 Silvy 4wd with the 5.3l and I get better milage then
>> > > >> that,
>> > > >> around 15 in town, BUT you have a crew cab and it wieghts more
>> > > >> then
>> > > >> the ext cab, plus I don't think the 05 is areodynamic. Isn't this
>> > > >> the
>> > > >> timeframe when they started changing the body style to the squared
>> > > >> off
>> > > >> front end again? When is the last time you had a service
>> > > >> performed?
>> > > >> That is going to hurt you some, dirty filter, etc..
>>
>> > > > what hte heck do you mean "Service"....
>> > > > You can service whatever you want and not gain 10mpg
>>
>> > > I'm not sure I follow your statement. The OP is asking about a
>> > > difference
>> > > of 37% max (290 miles vs. 400 miles on a 26 gallon tank), not the
>> > > almost
>> > > 100% increase you suggest with a 10 mpg gain. Of course it would be
>> > > helpful
>> > > to know what the actual MPG is, rather than the range on a "tank" of
>> > > gas.
>>
>> > > To , have you calculated your actual MPG, of do
>> > > you
>> > > just fill up when the gas gauge indicates you are low and compare how
>> > > far
>> > > you have driven since the last fill up? It may be something as
>> > > simple as
>> > > the gauge indicates low when you have several gallons left. From
>> > > your post
>> > > of MPH vs. RPM it sounds like your OD may not be engaging, which I
>> > > don't
>> > > think would account for the kind of MPG loss you claim, but real
>> > > world MPG
>> > > numbers may tell a different story.
>>
>> > Also, when I press the overdrive button, the enginge does not increase
>> > in rpms like my old ford. A Gm mechanic said that is perfectly normal
>> > for it to not increase rpms. But I don't know.How many gears should I
>> > go through before i hit overdrive?- Hide quoted text -
>>
>> > - Show quoted text -
>>
>> Your fuel tank is a 26 gallon tank, you have a 5.3l 1500 crew cab, 4
>> wheel drive. The 2008 version is EPA rated at 14 city, 19 highway.
>>
>> You have not told us what rear gear you have, you have not told us
>> your driving habits (all city, all highway, mix), you do say you have
>> a light foot. You have not told us at what point you fill up,
>> completely empty, 1/4 tank etc. So this is the best you are going to
>> get for an answer.
>>
>> A 26 gallon tank at 290 miles is approximately 11.5 MPG, so yes, you
>> seem to be a little off from what it should be.
>>
>> As a comparision, with mine, with the only differences being year and
>> that I have the extended cab, I am getting around 350 in the city,
>> which puts me closer to the EPA rating.- Hide quoted text -
>>
>> - Show quoted text -
>
> I fill up when the light comes on and the miles are city and highway.
> I do not know what gears I have. How can I find that out ?

There should be a tag on the differential cover that is held on by one or
two of the differential cover bolts. It'll probably be 3.73 or 4.10. If
there is no tag. you could lift the rear wheels off the ground, put the
transmission in neutral and count how many times it take to turn both wheels
in order to get the drive shaft to make one complete turn, or a dealer could
probably tell you just be running the VIN.
 >> Stay informed about: poor gas mileage 

>
> I fill up when the light comes on and the miles are city and highway.
> I do not know what gears I have. How can I find that out ?

Look in the glove box for the RPO options tag. It will tell you what
gears it has along with most of the options on the truck as well.
Then look at
http://www.wiu.edu/users/muwtj1/rpocodes.htm
or http://www.c2e.info/rpocodes/
to find out what they mean.




--
Steve W.
Near Cooperstown, New York

Life is not like a box of chocolates
it's more like a jar of jalapenos-
what you do today could burn your ass tomorrow!
 >> Stay informed about: poor gas mileage 

Ed H. wrote:
>> I do not know what gears I have. How can I find that out ?
>
> There should be a tag on the differential cover that is held on by one or
> two of the differential cover bolts. It'll probably be 3.73 or 4.10. If
> there is no tag. you could lift the rear wheels off the ground, put the
> transmission in neutral and count how many times it take to turn both
> wheels in order to get the drive shaft to make one complete turn, or a
> dealer could probably tell you just be running the VIN.

Or look at the sticker in the glove box

G72
AXLE REAR, 2.14 RATIO


G75
AXLE REAR, 3.62 RATIO


G76
AXLE REAR, 3.36 RATIO

G90
AXLE REAR, 3.15 RATIO


G91
AXLE REAR, 3.08 RATIO


G92
AXLE REAR, 3.08 RATIO, PERFORMANCE


G93
AXLE REAR, 3.27 RATIO


G94
AXLE REAR, 3.31 RATIO


G95
AXLE REAR RATIO, ECONOMY


G96
AXLE REAR, 3.55 RATIO


G97
AXLE REAR, 2.37 RATIO

GT4 AXLE REAR, 3.73 RATIO
 >> Stay informed about: poor gas mileage 

2006 1500 Z71 5.3L 3.42 gears Reg Cab around 5k on the odometer

Most of my driving is just puttering around town and I get 15.5 MPG.

Drove it 1100 miles with about 1000 lbs in the back and got 19 on the road.

I buy cheap gas, Wal*Mart, Kroger's, etc.

Karl


"Bill" wrote in message

> Overdrive, that is a good point.
> Can you feel it shift through all the gears into OD?
>
>
> "Ed H." wrote in message
>
>> My Chevy is a diesel so I can't compare it to your GMC, but comparing it
>> to my Dodge, which runs just below 2000 RPM at 70 MPH, it may be that the
>> overdrive isn't engaging, which could account for the difference. Please
>> note however, the overdrive on my Dodge is pretty tall (IIRC .67:1 gear
>> ratio).
>>
>
>
 >> Stay informed about: poor gas mileage