i just got a 2009 sierria with the 5.3 and 6 speed

the window sticker reads 18mpg town and 29 hwy... i get 16.5 hwy... i figured the posted numbers were BS but i should be at least able to get the in town figures on the hwy...

also the tranny seems to do some stupid shifting it seems like its thinking about shifting before actually doing it. its bad if your decelerating then have to accelerate. also it seems like there is lots of torque removed at shifts. also if you use the manual mode and shift at 5000rpm it bogs way down and takes .5-1 second to shift...

my third gripe with this truck is cruse control, my drive to work has a few slight hills, when on cruise the speed drops about 3-4mph then the tranny shifts down 2 gears and it ends up 3-4mph above the set point at the top of the hill.. this is probably what is killing my mpg, my 04 2500 holds the speed almost exactly, its actually nicer to drive..

can any or all of these issues be solved with a tune?

i have efi live v1 that i used to add e fans and firm up the shifting on the 04, would i be better off upgrading that so i can tune the 09 or buying a mail order?

is there any available modified efi live tunes for the 6 speeds that i can use as reference if i get the v2?

let me know as i just sold the 2004 and i may be regretting it if this 09 doesn't start to behave..

 

Have you ever reset your DIC?

I know my truck was getting 15.8L/100km when I bought it...second tank of fuel it now gets 14.2L/100km.

If you have never reset it, you are still averaging with your brake in mileage...which is ***** high.

As for the 6 speed...it does down shift excessively...but its 1 million times better than the 4L60E gear hunt.

There is also a tonne of TM (Torque Management, in case you didn't know what that was)built in these trucks.

 

custom tune will solve ALL

 

i am figuring out the mpg manually my truck doesn't display it... i fill my tank and reset my trip meter, then next fill up i write down the distance traveled and fuel used.

14.2l/100km is about 16.5mpg so i guess that's what these get

is there any link to some stock or modified tune's for the 09's with 6 speeds? i cant find any on Holden crazy.

 

You also have to take into account that the EPA rating is on a level road, with no wind drag and at 55MPH...Also with the truck in V4 mode.

Bet you have hills wind and drive "slightly" faster.

 

i run at 58-59mph

 

I agree a tune will help, but how many miles do you have on the truck? As I starting getting miles on the truck, the gas mileage got better.

 

17,000 17,500 range

 

but you have to accelerate to that speed. EPA ratings are done at speed. Its more of an instantaneous rating than an average IMO

 

does anyone have a tune for the 6 speed tranny that they are willing to share? i am getting the updated efi live cable but there is no modified 6 speed tunes to look at on the holden crazy site, i may get the blackbear tune with my cable buts its a extra couple hundred and i am really only unsure about the tranny stuff, i read that you can pshyically damage the 6 speeds if not tuned proper.