duramax smoking problem
#1
duramax smoking problem
this is for a friend, he has had the injectors replaced a few months ago due to fuel in the oil. now not all the time but from time to time when he comes to a stop he will try to take off and blow black smoke and no power. took it to the dealer they replaced the GP module for some reason no cel or problem starting. other details about the truck idk im pretty sure its a lb7 due to the injector problems and early 2000s. doesn't do it all the time and no other problems, any questions ask. sorry for the lack of info
#3
#4
if its returning too much fuel it would barly fire injector .... like running lean , it would sound almost like a ping.
the fact that it only does it at stoped ... thinking fcim not getting or sending enough volts @idle maybe ???
check injector wiring ( use ohms and to test from end to end , contunuity would be good to do a shake test to see if cont. stops when shaken ) ...
keep posted , could also be a weak CP3, low fuel pressure causing low or dribbling fuel spray pattern as well , causing fuel to puddle on top of the piston ?? hmmmmm ...
the fact that it only does it at stoped ... thinking fcim not getting or sending enough volts @idle maybe ???
check injector wiring ( use ohms and to test from end to end , contunuity would be good to do a shake test to see if cont. stops when shaken ) ...
keep posted , could also be a weak CP3, low fuel pressure causing low or dribbling fuel spray pattern as well , causing fuel to puddle on top of the piston ?? hmmmmm ...
#5
i know you don't know what motor or year it is, but if it's newer with the vgt turbo and the turbo is sticking all the way open it will cause this. It's just like trying to spool a big single. i saw a 6.7 cummins that did this every once in a while. Being as it's not all the time i'm inclined to throw out a weak cp3 or injector problem.
#6
#7
Join Date: Dec 2010
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i would say:
MAF issues, clean and/or replace or
Boost leak, should be easy to tell as it will normally hiss or squeal but not always. check for loose boots or holes rubbed through boost lines, or
possibly a bad turbo. check for play in the turbo shaft and for smoothness in rotation.
Also, double check for stored codes if there is no CEL.
low fuel pressure will cause a CEL (unless it has been disabled by a custom tune) so it wouldn't be my first guess.
MAF issues, clean and/or replace or
Boost leak, should be easy to tell as it will normally hiss or squeal but not always. check for loose boots or holes rubbed through boost lines, or
possibly a bad turbo. check for play in the turbo shaft and for smoothness in rotation.
Also, double check for stored codes if there is no CEL.
low fuel pressure will cause a CEL (unless it has been disabled by a custom tune) so it wouldn't be my first guess.
#8