okay so i dont know whats going on with my truck i had it in the dealership getting the map sensor replaced and then got it back and my milage went to crap went from 625-675km a tank to about 500-550 km. so i got the oil changed to synthetic changed fuel filter and air filter added some addatives nothing still down the drain. i did not change driving habbits or anything this is all most all high way km . any one got any ideas

any one got am ideas i am lopen to anything

wow id be more then happy with getting 500km outta a tank. right now my dic says i can get 325km outta my full tank.

it has alot to do with the map sensor

it has alot to do with the map sensor

okay so what can i do about it take it back to dealer and complain? i just want my milage back

Lol quit using that smoke switch on the way to work everyday and i bet it will improve a little

Lol quit using that smoke switch on the way to work everyday and i bet it will improve a little

haha :) i didnt touch it today and it burnt just under half a tank for 200 km something is seriuosly wrong. but i dont know what any help is much appreciated.

I used to constistently get 400 to 450 miles out of a tank and now Im lucky to get 350. Dont know why but I would like some body to tell me. I have had people tell me that its because of the low sulfur fuel most places carry now

hmm usually when u get past that 60,000km mark on a new engine the mileage goes up not down. (break in peroid)

hmm usually when u get past that 60,000km mark on a new engine the mileage goes up not down. (break in peroid)


Thats exactly what I have always thought

Evidently not because I went from 22 down to 17 mph at 70 mph. I dont know whats wrong either.

Rodder 55 I just did 844 km on Feb 22 to 24 . Drove at about 120 from Edmonton to Banff & then to Radium Hot Springs. I up filled at Cochrane & I took on 104 liters & I had traveled 844 km. That works out to about @3 mpg. I think it impoved then I replaced the fuel filter.

06 GMC ext cab lb

Contact dealer and ask if they reflashed the ECM for any reason.

Contact dealer and ask if they reflashed the ECM for any reason.

i actually know for a fact that they did cause i had to update my predator to get it to work right.

would this update have anything to do with this?

Its more than likely a combination of the new ECM update and the crap fuel that comes around in the winter. I know I had my ECM reflashed last summer and mileage went down as well. Time will tell though, I don't even have 50k on the truck yet.

My buddy has a 2006 lbz and and last summer he had egr code coming up so the stealer cleaned his egr and reflashed the ecm. So he had to update his predator also to get it to work. And ever since then his milage has been 2 to three miles per gallon less. He talked with the dealer and they said they had no idea why it would be less:mad:

okay i am thinking this reflash really affected my truck not only have i had problems with my preadator and my mileage but my manual shift mode hasnt worked since its been in the dealer ship. it just dont add up it seems to pull when in gear stopped harder than i remember not sure if the new 285 will make this happen.

okay i am thinking this reflash really affected my truck not only have i had problems with my preadator and my mileage but my manual shift mode hasnt worked since its been in the dealer ship. it just dont add up it seems to pull when in gear stopped harder than i remember not sure if the new 285 will make this happen.
Yeah, if you do not need an update do not get one from the dealers. I talked to the mechanic at my dealer & he told me if you are getting good mileage do not update because all the guys that come in & after the update the call him complaining about the mileage. He said he can not just undo an update either he said.

Winter blend has alot to do with crappy mileage this time of year, but a 50% drop right after a MAP sensor replacement.....definately go back to the dealer. Either the MAP is causing this or you have a leak in your fuel system.

i am thinking of getting my buddy to reflash it with his efi live would you recomend this

i am thinking of getting my buddy to reflash it with his efi live would you recomend this


Ive been thinking about sending my PPe back and have them reflash it, maybe that will help some

did they reconnect all the sensor wires they worked on. Had this happen with a gasser. Left off one of the sensor plug in connectors and they truck ran, but mileage was crap.

i dunno i was going through some big drifts today and got hung up on one so romp on er and my truck died so after i started it agin it threw ten codes i am gunna start a new thread tomorrow giving a better xplnation

Dealer had to drop my trany and replace the rear main seal and a gasket and they re flashed the ecm on my 06 lbz. I lost 5 mpg i took it to a different dealer and they re flashed it and i got 1 to 2 mpg back.

thats what i would be hoping for if i got it reflashed

If they reflash the ECM, would the tranny get reset also? I've heard it takes several thousand miles for it to relearn if you don't have a quick relearn on your programmer.

Are you throughing any codes? I just blocked my EGR and my MPG went to hell. I am hoping once I clear the codes it will improve. Hoping that the truck is altering fueling because of the code.

When fuel mileage and seat of the pants performance drop, check the air charge plumbing. That means all the boots and aluminum boost tubing. I'm thinking you may have rub through somewhere. I'd really suspect boost loss somewhere. If a visual inspection of all joints and abrasion areas reveals nothing, the following may help. And since they changed the MAF, remove the intake tube and look for stupid things like a rag across the inlet, etc.


The quick and easy way is to use a can of starting fluid. Just a little squirt while the engine is idling along suspect locations. Just a little fart here and a little fart there. And listen for rpm change. Also important to remember is that when doing the pass side, that the fumes can be drawn to the air box and give a false RPM change.

hmm i am a little skeptical to use starting fluid cause i can not afford for something seriously bad to happen. and i have heard its extremely bad for these trucks?

hmm i am a little skeptical to use starting fluid cause i can not afford for something seriously bad to happen. and i have heard its extremely bad for these trucks?
Well, then a thorough visual inspection of the tubing is in order. And, pay careful note to the joints at the boots. They can be evenly oily, but there should be no streaking.