HI I have a 96 powerstroke, i was driving through the mountains this week and when i go downhill everytime i speed up the truck smokes a big puff of blue smoke. its like it gets kinda flooded or something, you get on the gas it runs a little rough then puffs out the blue smoke and then it runs fine again. Funny thing i ended up behind a Older IDI ford diesel and it was doing the same thing as mine lol.. any ideas? ohh and the truck is 5 speed. also couple notes it smokes more than normal at till its warm, glow plugs system is good the trucks starts fantastic i just did the glow plugs. when you first take off it hesitates and smokes like crazy till you get it up to 2500 rpm or so and then it clears up and runs great. i was thinking injector o-rings but I'm not sure. thanks
Martin

 

Do you have an exhaust brake?
Blue smoke on deceleration is valve guides. Exhaust brakes can hurt valves.

 

no exhaust brake on my truck.. valve guides hey thats not good lol. but that wouldnt cause the misfiring would it? best i can describe is when its going downhill on compression (because im not on the gas) is when it seems to flood itself or something, when i do get back on the throttle is when it smokes, runs rough a little and then clears up.. It is using oil (not leaking). maybe i shouldnt worry about it?

 

I have a 5 speed in mine and sometimes get a puff of blue when I first get back on the pedal after downhill compression braking. Not blue while coasting down though. No stumbling either. My EGT will go as low as 200 while compression braking, I figure it's either incomplete combustion due to the cooler temps or as Cuda suggested my valve guides could be leaking a bit. With 234K on the clock I'm not too worried about it because it starts and runs fine and uses very little oil, a quart or so in 3000 miles at most.

 

Ya mine uses a little more oil than that 1 litre every 2000kms. The truck has 330k on it so as long as it doesnt get worse Im gonna leave it alone i think. but Im gonna switch it to AmsOIL. When i did with my IDI F-250 it cut the oil consumtion in half for whatever reason.