Chevy and GMC Duramax Diesel Forum banner
  • Hey Everyone! Enter your ride HERE to be a part of this months Ride of the Month Challenge!
1 - 16 of 16 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter · #1 ·
I have a 2007 1/2 (basically new body), I have had a H&S Performance Black Maxx programmer, AFE cold air intake and 5" exhaust /w DPF delete on for about 3 months. I do not run it very hard, did it mostly for MPG as I drive alot. When I first installed truck ran great plenty of power for passing, it would actually spin the tires on takeoff if not careful and was averaging around 20 mpg. For about a month now I am barely getting 15 mpg now. It cuts out and almost seems to sputter with knocking under any kind of acceleration and is very sluggish. There are no DTC errors. I dont want to take to dealership because of mods. Any ideas. thanks
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #2 ·
OOPS LMM Sputters and Knocks..
 

·
Registered
Joined
·
21 Posts
when's the last time you changed your fuel filter?
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #7 ·
The filter was the first thing I changed. When it ran good there was a good bit of black smoke when I got on it. Now there is not much. The tech for the programmer told me to set my display to show boost, rail pressure, egt and trans temp to see of maybe one of them had a limit set on it and it was shutting down at the limit. But that does not seem to be the case.
 

·
Registered
Joined
·
1,269 Posts
Have you tried removing your program ??
 

·
Registered
Joined
·
2,384 Posts
^^ Agree'ed... If you like your truck and driving just do it now.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #11 ·
I have not removed it. If I set it to stock it doesnt seem to hesitate and sputter but doesnt run anywhere like it did pre-programmer. I will uninstall and see. I cant run long without programmer because of DPF.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #12 ·
I have not uninstalled and disconnected. When I set it to stock tune it does not cut out but does not have the same power as pre programmer. I will uninstall and see how it runs. I cant run it long because of DPF delete.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #13 ·
Sorry for duplicate did not see it was on second page. Thanks for ur help I will see what happens.
 

·
Premium Member
Joined
·
9,706 Posts
you said the first thing you did was change the filter, did you mean that you just did that when the problem started, or you did it before you put the programmer on? It really sounds like you're not getting enough fuel, and usually a plugged filter is the culprit.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #15 ·
I changed it when it started acting up. What would normal rail pressure be under 1/2 throttle acceleration.
 

·
Premium Member
Joined
·
9,706 Posts
That depends on the tuning, but it should be somewhere well over 10,000 probably closer to 20,000. But it's really dependent on the tuning. The tuning commands a certain pressure, what you want to look at, is desired versus actual and see how far off they are. This can cause some issues if you can't keep pressure.
 
1 - 16 of 16 Posts
Top