Puff Of Smoke On Initial Acceleration

Keith Browning · September 10, 2020

'06 F250 with 157K - on initial acceleration like when stopped at a traffic light there is a decent puff of white or bluish smoke that is repeatable every time. Engine must be warmed up AND happens ony in gear - will not smoke goosing the throttle in neutral.Engine runs well and sounds good. On the first road test I also had intermittent heavy black smoke which made me think EGR valve. No codes so I went to data logger and started playing with the valve and sure enough, the position sensor was erratic on the initial step and the valve would not open all the way, closed voltage was 0,91 as well. Pulled the valve and sure enough it was caked up, no signs of moisture though and the coolant is full. Scraped some carbon and replaced the EGR valve - black smoke appears to be gone however the puff of white still remains. It lingers unlike coolant will dissipate with a leaking EGR cooler so I have about ruled it out.

Pulled the down pipe and looked at the turbo and do not see any oil or wetness but there is one area of built up carbon at the downpipe connection that looks like wet carbon. I am not convinced there either.

Thought maybe an injector doing something but there are no misfires. I have never seen diesel base engine do this either as usually something is torn up and they smoke all the time. This may require removing parts and inspecting or replacing things but as usual the customer has no money... I might suggest trying a turbo and peek at the EGR inlet while the turbo is out...

Any thoughts?