Posting for a friend, His 03 duramax is smoking at and idle a white and light blue color smoke it clears up when driving. Fresh filters and oil make no difference. The truck has 111,000 miles upgrades include 4 inch exhaust, s&b airfilter, banks sixgun and a set of gauges turbo, fuel, pyro. Thanks for any info.

 

Get the injector ballance rates checked

 

probably needs a set of 8 injectors

 

now it will no shift out of third gear

 

Sounds like injectors!!!

 

Are there any Engine codes?? this sounds like NSBU switch or output speed sensor issues

 

might be in 4th gear