"07" LBZ Warrantee?

[TJNE]

I think I may be having injector issues, I'm kinda new to diesel. I have a 07 classic LBZ w/66k miles. I'm dissapointed in the 12 mpg around town (compared to my fathers 08 Cummings @ 17 mpg). I had it in for the EGR clean and it did not seem to help. What else would they have checked, it had 5 codes but they said the EGR problem probably triggered the other codes. Makes sense, the light has not come back on since. I'm affraid to take it back in and find out it will take big $$$ to solve my mpg problem. Its bone stock except for a K&N filter. It runs smooth and has lots of power and acceleration, it has a cloud of smoke when you dump the throttle but cleans up in a few seconds. I tried injector cleaner which helped mpg while it was in the tank but went back to same millage when it was used up. I have done the millage by hand and the DIC is with in 2-3 tenths. 1. Should I take it in? 2. What is covered? 3. What maybe some problems? 4. Any suggestions before I take it in?

All help is greatly appriciated. Thanks in advance.:eek::confused:

[DmaxMaverick]

The standard GM Diesel engine warranty is 5 years or 100K miles. Covers everything between the valve covers and the oil pan, fuel system, and any emissions components (including EGR and engine electronics). The EGR service should have been a warranty issue. And, GM, or any mfg, won't give you much satisfaction when it comes to mileage complaints. You should be doing better, but they won't help unless a problem can be identified. There are too many variable effecting fuel economy, and the problem is usually driving habits.

[TJNE]

I chaulk the smoke on hard acceleration up to putting around most of the time. I try not to get above 2000 rpm, usually around 1600-1700 rpm. Is there another complaint I could claim to get the dealer to look at the same things they would look at for mpg problems? When I pulled my 7000 lbs travel trailer I was getting about 9-10 mpg's, the same I used to get when I pulled it with my previous 1/2 ton 5.3L gasser. It pulled it a lot easier but the millage was the same. I have been reading on here about injector balance, fuel pressures, exhaust temps etc. is that something the dealer should looked at? I haven't called the dealer yet, I am trying to educate myself before I call so I can tell if they are blowing me off or not. I have had it there once before (EGR) and was treated well but I like to have some info before I get into things.

Thanks again.

P.S.This website is great, I get a lot of info from it. Some really informative members. Keep up the good work!:D

[DarylB]

You're running larger than stock tires which can cause a decrease in mileage. Are you adjusting your calculations for the increase in tire height? Did your mileage drop after installing the K&N?

[NutNbutGMC]

In my opinion from owning several of these machines (LN7s and LBZ) the Duramax (in particular the LBZ) just doesnt' get mileage that is worth bragging about. I currently have a 2007 LBZ and the mileage stinks. That said, I don't care in the sense that MPG is not my expectation of the machine. It gets what it gets. However, better MPG would make me a happier owner. This is likely my last Duramax.

I doubt that your injectors are the problem. Generally speaking, I have concluded that it's the nature of the engine. GM never made this the engine that it should have been (or more so what I expected while watching the evolution of the different engine versions). More and more my opinion changes about this engine. It's not what it should be. It's not much more than a cheap knockoff. No offense to anyone here but is sorta' speaks for itself, from my viewpoint.

[Mark Rinker]

In my opinion from owning several of these machines (LN7s and LBZ) the Duramax (in particular the LBZ) just doesnt' get mileage that is worth bragging about. I currently have a 2007 LBZ and the mileage stinks. That said, I don't care in the sense that MPG is not my expectation of the machine. It gets what it gets. However, better MPG would make me a happier owner. This is likely my last Duramax.

I doubt that your injectors are the problem. Generally speaking, I have concluded that it's the nature of the engine. GM never made this the engine that it should have been (or more so what I expected while watching the evolution of the different engine versions). More and more my opinion changes about this engine. It's not what it should be. It's not much more than a cheap knockoff. No offense to anyone here but is sorta' speaks for itself, from my viewpoint.

I completely agree with everything he said...plus my .02 worth...


As an owner and thrasher of '01, '02, '04, '05, and two '06 Duramax's, there is a serious unloaded 'around town' mileage drop with the LBZ. Good news is the loaded, towing mileage is very similar to earlier versions. Mine are both 3500, one dually, one SRW but there is no doubt that its not just the extra frame weight or duals that attribute to the drop in mileage - I suspect its simply the extra fueling on top for the additional 60hp GM brought to market. The biggest fuel waste is just 'tooling around'...when you are towing and using the extra HP for work, it becomes a benefit, and less of a detriment.

Sad thing about the overall evolution of the venerable Duramax - it started out rock solid in '01, arguably hit its peak in '02 with improved ECM and programming, and has slid downhill (starting with the LLY in mid 2004) in many respects since then.

Don't get me wrong - its still a very potent and trouble-free engine, but is now encumbered with emissions bull****, compromises for ULSD and bio-blends, and now - enter the dreaded particulate trap with regen cycles.

The 2002-2003 LB7 will always be my favorite Duramax. Add about a +40hp tune, dial in some more boost, and let 'er buck to the tune of 18-21mpg empty highway mpg, and 10-12mpg loaded towing.

LIKE A ROCK!

[Kennedy]

Persoanally, I think they just keep getting better. A guy needs to neuter some of the emissions junk. but the LBZ and LMM are as good or better on MPG than any IMHO.

[JohnC]

My '06 LLY (LBZ in sheep's clothing) consistently gets 20-21 unloaded highway MPG.

[TJNE]

(Mr. Rinker) explain "particulate trap with regen cycles". I have heard somethings about this but the explinations I have gotten don't make complete sense.
(A little history, I was ASE certified and a GM tech in a small dealership 20 some years ago, very little diesel exposure then. I am mechanically inclined but I have been out of the business for sometime.)

The PCM was reprogramed (by dealer) for the larger tires, then I find out it will not help milage, $85 wasted. I had the injectors cleaned then I find out it doesn't have that much affect on diesels, another $85 wasted.

(DarlyB) The K&N filter did not seem to have much affect, but it needed a new filter anyway and I can recharge this one, I think money saved in long run.

I read up on Duramaxes before buying (in this forum), and what I read was the LBZ is one of the better ones for mpg's. Now some are saying that LBZ's are not that good, sounds consistant with what I am experiencing.

I would like to put the stock size tires on it but these are brand new and I can't afford to replace them. The 285's were on it when I bought it used. It looks like I'm going to have to deal with it, I love the truck but I'm not crazy about the milage.:rolleyes:

(Mr. Kennedy) What can I neuter with out voiding the warrenty? I would love to get a programmer and other upgrades but I don't want to void it.
I'm a public servant and don't have alot of $ to spend.

[JohnC]

Have you verified the accuracy of the speedometer and odometer?

Does the fuel used as shown by the DIC agree with what you're putting in the tank?

If so, next time you get out on a flat stretch of highway set the cruise on 65 and zero the MPG in the DIC. Drive for 20 miles or so at a constant speed and see what you get.

[TJNE]

Have you verified the accuracy of the speedometer and odometer?

Does the fuel used as shown by the DIC agree with what you're putting in the tank?

If so, next time you get out on a flat stretch of highway set the cruise on 65 and zero the MPG in the DIC. Drive for 20 miles or so at a constant speed and see what you get.

The fuel used and the DIC are with in .2gals, also the DIC mpg's and hand calc. are with in .2 mpg's. The speedometer is very close to the GPS at around 35-40 mph's but haven't tried it at 65 mph. I have not had it on a the interstate yet but I will soon.

[TheJDMan]

You will be plesantly surprised by the hiway milege. My 07 Classic LBZ gets around 12-14 in town but on a hiway trip (no trailer) that will increase to around 21-23. This truck really likes to run at hiway speeds.

[NutNbutGMC]

You will be plesantly surprised by the hiway milege. My 07 Classic LBZ gets around 12-14 in town but on a hiway trip (no trailer) that will increase to around 21-23. This truck really likes to run at hiway speeds.
I wish I could say the same. Highway mileage for me (stock) is still the 11 - 13 MPG in any scenario.

If I could get 21 - 23, I'd park my Honda Accord for a machine like yours.:eek:

[TJNE]

The best milage I can get is a cruise around 45-50 mph (19-22 mpg). The interstate run is about 16-17 mpg. The LT285's have something to do with it but I can't help think something else is causing the low mpg.

[mr. monte]

the 285's are killing your mileage, i noticed a drop just going to 265's

[TJNE]

What was your millage difference before and after?