Deceleration then Re-cel problem

[xohcef]

So I live in Colorado and quite often I find myself driving through the mountains. On the big inclines through the passes she does great, with more than enough skinny pedal to pull what I need through the hills. However, my problem starts after I've stayed in gear with no throttle % while going down hill. The truck goes down the hill normally but, as soon as I tip back into the throttle the truck will hesitate, stumble, bang, and pop just before chugging a big cloud of white smoke and clear up. It runs normal after this and I've noticed that if I just give it a good goose right when I notice it, it will clear up quicker. Any ideas? Thoughts? Fuel system is regulated at 15psi. The only thing I don't have in the signature is the NV5600 swap, which i would not think to have any affect to my symptom. Thanks in advance.

[cougar]

My thoughts?
Turbo leaking oil into the intake side
Valve stem seals leaking
Dribbling injector

[dpuckett]

What do your EGTs drop to on the long down grades? My thinking is, the cylinder temps could be getting cool enough to almost put the fire out, so to speak, and the chugging, puffing, white smoke for a second or two could be starting the fire again. Slight timing bump (couple tenths of a mm) could help if you're at or near stock.

[xohcef]

Thanks for the couple responses. Cougar, I'm thinking I have a hurt injector or 2. No oil in charge pipes, nor down pipe. Dpuckett, the egts go to practically nothing. They do drop right on down. My timing has always been a shot in the dark. Even with completely stock pump settings it required a lot of timing to idle, and free rev without hesitation.

[cougar]

I'd say, pull your injectors and take a look. Oil getting into the combustion chamber can temporarily foul an injector and over time coke it up to the point where it doesn't spray properly anymore.

[CumminsPower59]

I've had this happen too. 2004, driving down Pikes Peak. My theory is that when the engine is at 0% throttle, its basically just injecting the "idle" amount of fuel, well, when the RPMs are up as coming down a grade, the engine is actually drawing more than "idle" amount of air in because of the engine speed, cooling off the combustion chamber enough that not all of the fuel is burnt. Look at the egt's when this is happening, the exhaust temp gets pretty low. When the throttle is applied, all that unburnt fuel ignites, making the truck run as you described.

Just my two cents....