Hi.
i have LB7 2002 Duramax, it´s a federal motor(no EGR system). my problem is that he spend so much fuel. Mpg is around 8-10 gallons on every 60miles.there is no hard start,black smoke or nothing. when i read it with TECH 2 there is nothing i can see that is wrong or out of specs. I can feel a lack of power but not so much.sometimes on highway driving i can feel missfire or it feels that way. is some that can help me? gallon i iceland is around 8 dollors so this is killing my and i´m starting to hate my DURAMAX.. not good.. hehe...

 

it sounds like injector problems. have you checked your oil to see if your making oil? u need to hook the truck up to a good scanner have have the injectors tested

 

Check to see what your making for rail pressure at idle and wide open throttle. If your pressure is low the truck will not burn the fuel correctly causing a lack of power and milage. If your not seeing a haze(smoke at idle) or fuel in the oil your injectors might be alright. Do a balance rate test. If non of them are + or - 4.0 or higher your alright.

 

now i have code P1781 transmisson control module. ????