2005 Z71 horrible mpg! Help!

[bsnbodybuilder]

Whats up poeple. Im new to here. Anyways i have a 2005 GMC z71 1500 5.3 with 3.42 gears. Im getting horrible mpg. I maybe get 250 out of a tank if that. I live in the country so not many stop lights or sign mostly highway. It just clicked over 100,000 miles and the only thing done is a flowmaster dumped. It still has 265s so that cant be the problem. it pops and little bit when i let off the pedal but i think that cause of backpressare. If yall could help me that would be awesome. Thanks!

[strafingmoose]

I am in no way a tech so take my advices with a grain of salt. Have your injectors checked/cleaned if needed. Also, others in here have told me O2 sensor can screw your gas mileage quite a bit and run too rich before even throwing a code in the console. Check spark plugs as well. Clean the throttle body with throttle body cleaner (spray can) and a toothbrush. If you've never done it, lots of gunk can come out.

[tyhuck]

And a Seafoam treatment.

[8.1HD/ALLISON]

What kinda milage you talking? And start with a tune up as stated above, if not done yet.

[tyhuck]

Just out of curiosity, how many 02 sensors do the 800 series pickups have?

[gmtech4]

Just out of curiosity, how many 02 sensors do the 800 series pickups have?

 

 

16.....

 

 

 

 

 

 

actually only 4 but thanks for the giggle lol

 

sry ,i had to

 

 

 

and as i did 14 yrs at the the dealer ,why do you guys use the 100 series for truck body yrs,no one uses that at the dealer ,strange ......eh? lol

 

is the 800 the 2000 to 2007?

 

what happenes after the 900s ??

 

 

what code designates this ?

 

serious ,always wanted to ask ,is my 93 a 400?,is there a 500 or 6 ?

 

idk

[rah7777777]

I have an 02 5.3L.

 

100% city (short trips) gets me 10.7 mpg, 75% highway-25% city gets me 17.4 mpg

 

Just for reference...

[chakis24]

and as i did 14 yrs at the the dealer ,why do you guys use the 100 series for truck body yrs,no one uses that at the dealer ,strange ......eh? lol

 

is the 800 the 2000 to 2007?

 

what happenes after the 900s ??

 

 

what code designates this ?

 

serious ,always wanted to ask ,is my 93 a 400?,is there a 500 or 6 ?

 

idk

 

 

400, 800, 900 are gm's internal designations for each trucks platform. since all the truck on those platforms are pretty much the same its easier to just say that instead of the year. yes yours is a 400. the 800s were the NBS '99 to the 2007 classic. after the 900 is the "k2XX" platform due in 2013/14.

 

i dont believe there was a 500 or 600. there is a 355 for the colorado, canyon, and h3. i think the trailblazer and envoy used 360.

 

and then there are the cars which all use the greek alphabet (zeta, epsilon, alpha, sigma, theta to name a few)

[gmtech4]

and as i did 14 yrs at the the dealer ,why do you guys use the 100 series for truck body yrs,no one uses that at the dealer ,strange ......eh? lol

 

is the 800 the 2000 to 2007?

 

what happenes after the 900s ??

 

 

what code designates this ?

 

serious ,always wanted to ask ,is my 93 a 400?,is there a 500 or 6 ?

 

idk

 

 

400, 800, 900 are gm's internal designations for each trucks platform. since all the truck on those platforms are pretty much the same its easier to just say that instead of the year. yes yours is a 400. the 800s were the NBS '99 to the 2007 classic. after the 900 is the "k2XX" platform due in 2013/14.

 

i dont believe there was a 500 or 600. there is a 355 for the colorado, canyon, and h3. i think the trailblazer and envoy used 360.

 

and then there are the cars which all use the greek alphabet (zeta, epsilon, alpha, sigma, theta to name a few)

 

 

thx ,just as i thought ,more useless info for a tech .............................

 

 

 

 

lol

 

 

its just not used by techs is all

 

thank you for the post

[8.1HD/ALLISON]

+1 on that Rob. I did 8 years as Gm tech and never heard of that till this website.