Is it the new body style Duramax? If so then its an LMM with DPF

 

Oh dang I missed where it said Hummer.. is this a custom deal? You should be able to look at the exhaust and see a cat and a DPF and Muffler.. If you see all three, then it could be DPF regen..

 

It most likely does not have a waste gate if it is newer than a lb7, but maybe a vane positioning problem.

 

My Vane Position sensor went out on my LBZ.. and I knew right when it happened that something was bad wrong.. I lost ALOT of power except thru one small section of RPM..


Make sure nothing is blocking the air intake, clean the MAF Sensor.. See if you are still having the problem..

 

It won't have a DPF because they stopped building the H1 before the new regs took effect. I'm not sure if it's a LLY or LBZ though.

If it only happened once I would just monitor it for now. Maybe unhook your Edge next time and see if it gets better right away.

 

Hummer offered the 6.6 Duramax in the H1 "Alpha" for the 2006 and very early 2007 model years. According to Four Wheeler magazine: "In H1 trim, the engine makes 300 hp and 520 lb-ft of torque, a lead-foot-inspiring 46 percent and 18 percent gain, (over the 6.5L) respectively".

H1 Alphas were NOT equipped with a DPF and do not go into active re-generation mode, hence the reason he's able to run B99 in it and not ULSD only.

I question whether your Hummer is approved for bio-diesel use. Most newer diesels are approved for B-5 or B-10 at the most. I would definitely check to see if it's approved for Bio-diesel use and at what concentration percentage. If you take your Hummer in for a fuel related problem (like you just experienced) and the dealer finds un-authorized bio-diesel in the tank, they can, and will, void your warranty.

I've never heard of any Hummer getting 22mpg, even the Alpha. Low to mid teens seem to be the norm.

As far as your smoke and high EGT's, it could have been a sticking injector, the trans failing to downshift with the engine under excessive load, or a momentary sneeze in the computer.

Any codes stored?

 

My dad's '05 did this a couple of times, but it was accompanied by a loss of power and a little stuttering. He started to run the grey bottle of fuel additive (Diesel Service??)(from WalMart) through it, and he hasn't had any problems since. He runs B99 also. If he forgets to add his treatment to a tank, he usually only gets a quarter of the way through a tank before it acts up.

 

Ok lets see. It's an H2, 6.6 Duramax installed by Predator motorsports not Hummer.