I have a 2007 2500 HD duramax with 50,000 miles on it that has had a problem from day one that the local dealer has been unable to diagnose after running test and talking to GM tech support on mutiple occasions. They claim there is nothing wrong and that this issue may be inherent or possible caused by the 35" tires. My opinion is that the problem has to be caused by some kind of sensor issue. This is my third personal duramax since 2002 and I also have two others in my business fleet. I also bought another 2007 3500 at the same time. The problem has never come up with any of these trucks and I have had larger tires on trucks before. An finally the problem is when air temp drops below around 60° the engine really starts clattering or what could best be described as extreme detonation or spark knock and the colder it gets the worst it seems to get. When it is hot outside you never hear a thing. You mainly notice it when at low RPMs, the engine is lugging and low turbo boost. Please help.

The Dealer Is B/s Ing You Go To Another Dealer.have The Dealer Check The Balance Rates On The Injectors Or The Mass Air Flow Sensor The Tires Have Nothing To Do With Detonation If You Look In My Garage I Have Big Rig Wheels And Tires On My Truck 225/70/22.5 With No Issues

Mass Air Flow sensor has been replaced twice and the injector balance rates where checked last winter. The thing that baffels me is that performance dosnt seem to be affected when stepping into it and problem is only noticable under a light throttle. And any idea why lower temps would make problem worse.

I Guess You Have Changed Your Fuel Filter Already?, Or Fuel Rail Pressure Might Be Low Or Could Be Injection Pump Giong Bad. Does Your Service Engine Light Come On If So Read The Code If You Have A Code Reader, I Am A Gm Tech I Would Have To Drive The Truck To Find Out What The Problem Is, And Run Test With My Tech-2 Code Reader While Driving The Truck, A Lot Of Dealer Techs Wont Take The Time To Find Out What The Problem Is Which Is Not Fair These Stealerships Like To Bullshit The Public

in my 04, it was caused by a cracked piston in cyl number 8, would sound like a spark knock under light acceleration or if i lugged the engine.....

Wow,did You Have Serious Tune In It Or Was It A Manufacture Defect

Or You Might Have A Cracked Piston

I change the fuel filter at least every 10,000 miles. The check engine light has never come on during the colder months when this has been a issue. Last year when fuel injectors balance rate where checked the checked fuel pressure, road tested with a annalizer and where supposed to have checked everything you mentioned. The truck has never used a drop of oil. Performance overall is good. The 2005 I used have had better low end pep but it also had a 5" exhaust, cold air box and an edge extreme. This truck also has an edge extreme and seems accelerate and pull my 40' 14,000 lb fifth wheel on the highway just as well as the 2005 did. However fuel economy is 2 to 3 miles per gallon less (Unloaded) than the 2005 and 7 to 8 miles less than the 2002 that I had first. I currently get about 12-13 mph but I have a heavy foot. All three trucks got about the same loaded with my fifth wheel which is about 7 to 10 mpg running at 70 to 75 mph. I still cant figure why this seems to only happen when its under 60 degrees F.

You May Have A Cracked Piston????

How can I persuade the dealer to check this.

First Of All The Tech Is Going To Look At The History Of The Ecm And Look For Any Programmers Installed By The Owner If He Find Any Your Warrentee Is Denied ,even If You Remove The Program They Still Leave Footprints If There Is No Programmer In The Ecm You Are Fine, If Your Truck Is Out Of Warrentee You Pay For The Tare Down The Dealer I Work At The Labor Rate Is $99.00 Per Hour , I Have A Question You Said In Your Rant You Had This Problem Sence Day One ,and The Dealer Said They Cant Find The Problem The Dealer Was Bullshitting You They Told You That Bullshit So You Can Keep Driving Until Your Warrennte Run Out So You Can Pay That Bill And Not Gm, I Know How Those Assholes Think. You Need To Do Some Research On Those Pistons Or Ask Any Body On This Site And Get Yourself A Lawyer If It Goes That Far

Lethal Weapon...did you get my PM?

Yeah ,desent Dealers Around Here Yeah Right They Are All Crooks And I Hate Working For Them

Thanks. I have tried 3 dealers in my area and I have not been happy with any of them.

No tuner never, ever? Sounds to me if you never tuned it ever ,and it has been doing it since day one ,then slam your foot to the floor and blow it sky high. Certainly this is extreme yet so is the Dealers incompetience. Good grief!