4.6L 2v puff sound at intial accelleration.
 

Hey all,

I have a 2009 E250 cargo van with the 4.6L 2 valve engine. Currently at 140,000 miles. Immediately following an oil change I did. I started getting a puff sound right at initial acceleration. It only puffs once unless you take your foot off the gas and let it rev down to idle. At highway speed no sound. Doesn't matter whether the engine is cold or warm. Thought maybe a vacuum leak but have inspected all. No effect to power, runs fine, idles fine. Any ideas?

Did you check the PCV valve and it's hose connections?

No, but I will today. Let you know.

PCV and hose are good.

If you didn't have the problem before the oil change, Did you recheck all your work for possibly disturbing a vacuum line/connection
Would you please provide some addl info as to just what "puff" means? Hesitation, slight backfire in intake, stumble etc. ?

It has no effect on engine performance that I can detect at any time. The best description I can give of the sound is like a when you spray window cleaner from a spray bottle. The sound the liquid makes as it leaves the nozzle. I did go through and check for any disconnected or damaged vac lines after the oil change. Nothing found. The only vac lines in "danger" are by the oil fill tube and they're fine. I didn't drop anything while working that could've hit any hidden vac lines either.