If someone can answer a question for me please. I have an 07 classic gmc 2500 HD 4X4 duramax I bought the truck from a dealer, should a stock truck smoke alot when accelerating hard, and when I try to pull my camper at 65 mph it has a constant trickle of smoke coming out the exhaust worst when I put the cruise control on. it had a programmer in it and I didn't know what type so I took it to the dealer got the computer reflashed and it still smokes alot when accelerating hard and same trickle when towing.

Anyone, I would just like to know if this is normal or not

A stock truck will puff a little smoke on hard acceleration now and then but shouldnt produce a steady stream. Whats the milage on the truck? Could be in need of an air filter. When mine was due it smoked quite a lot.

I just got my '06 LBZ emissions tested in Colorado... They do load tests at 40, 50 and 60 mph or something like that. My truck didn't do so well, with the highest opacity at 40mph, 27% (35% allowed). They guys said that causes for excess smoke could be dirty air filter, dirty fuel filter, injector cleaner additive, or bad injectors... Filters are good, I'm not running cleaner... NFG 4 me...

My truck pushes a good bit of smoke under load, and when accelerating, each shift has a little puff of smoke too... More than it should I think... They said normal for an '06 vintage would be less than 10%, even with the 130k miles on my truck. It doesn't use a drop of oil in 5000 miles... time to check out injectors I guess... They guys said that some trucks have a 200k warranty on injectors. I think it's only the very early Dmaxes though...

Good luck to us both!

My LBZ seems to build up alot of soot in the cat if run in lite load conditions for an extended time period. It will smoke at traffic lights and slow speeds when cat is needing to be blown out /gotten real hot. My solution is to get it good and hot a couple of times a month. During towing season typically not an issue....

Thanks for the replies, Truck has 95,000 miles and new air filter. being that it's a diesel I figured it would smoke a little while accelerating hard but my biggest concern was the constant smoke while towing around 55 mph going up and it's constant even if I hold one speed. I have friends with 250 diesel trucks with same size fifth wheels around 8,500# to 9,000# but i'm the only one leaving a trail of smoke.