My 2004 duramax is skipping and smoking at idle, is there something specific i should do or look at? I have used all the old fuel and did fresh fill-up, changed fuel filter, there has never been any codes thrown. Your help would be appreciated. Thanks in advance.

 

what color smoke? that would be a good start.

 

9 times out of 10 it's injectors on these motors

 

I have a buddy that his started smoking and got worse and worse and worse, had a crack in the intake, Dusted.

 

i would bet its the injectors?

 

the smoke is light gray. thanks for the answers. I finally took it to the stealership, and to be sure and 88 bucks later they say 4 7 and 8 are leaking. (into cyl. not oil) How can they specify the leaking cylinders with only a obd 3 hook-up? I call BS. but now on to ordering my long overdue performance injectors. I am open to suggestions on what to buy. Thanks.

 

Thats what my buddys truck was doing, and the dealer did the same thing and said the same thing and told him he was down 30% on power.

 

you can pop test the newer diesels using certain scan tools. my snapon can

 

its the injector balance rates that they can test with the GM tech II, I can check it with my EFI live as well

If the injector balance is +/-4 in park or +/-6 in gear then the injector is out of balance and is usually a sign of a cracked injector body, grey/blue smoke is a very clear indicator of a bad injector or two

I suggest getting new Bosch injectors unless you're planning on making well over 500hp, they are a waste if you only want 500hp or less