Looks like that is the PCV gunk that gets pushed back into the intake system under boost. Without looking at an acutal Lightning in front of me, I can pretty much bet that the clean air end of the PCV system is connected ahead of the blower, but after the MAF. The fresh air supply side of the PCV system is always after the MAF, so that no air in the combustion process is left unmetered. The fresh air that gets drawn through the crankcase via manifold vacuum at the PCV valve gets sucked back into the intake and makes up a small part of your A/F ratio. When under a lot of boost (thus more blowby past the rings and into the crankcase) the PCV system gets deluged with more volume than it can handle, so even the clean air supply side of the PCV system gets a reverse backflow of crankcase gasses that can't get out of the crankcase any other way because the PCV valve is closed due to boost pressure. Of course, traveling along with these crankcase gases is a small amount of oil mist that creates this gunk in your intake.
Now most of us here see a PCV system as an emission requirement, but it actually helps keep your engine oil cleaner between oil changes, but it can only function as designed with manifold vacuum present at the PCV valve. It keeps the acids and other nasty blowby junk from accumulating in your oil and shortening its useful lifespan.
So with over 100k miles on the engine, you can bet that there is more piston ring blowby (thus more crankcase gas volume) than there was right after your engine was broken in. Unfortunately, this gunk that builds up on your intercooler surfaces cuts down on intercooler efficiency. You may very well see some improved track times after cleaning a filthy intercooler.
Now a lot of you with boosted engines may be asking, "How do I keep this from happening to my engine?" The simplest fix would be to put an aftermarket air/oil separator inline with the fresh air supply hose for the PCV system to cut down on the oil mist traveling back upstream. A more elaborate fix would be to convert over to an open crankcase and do away with the PCV system all together. If you do this your A/F ratio will be off due to no more measurement of the PCV fresh air component, and it would be in your best intrest to update your tune.
Now my 2003 Cummins Diesel powered Dodge Ram simply runs a road draft tube off the valve cover to get rid of crankcase gasses. This way, the intake system always stays clean and intercooler efficiency never diminishes. On a Ford Powerstroke, the crankcase is closed and blowby gasses are recirculated back through the intake system. This is why when you have the intake boots off of a Powerstroke, they always have an oily film on them. Even the intercooler walls and turbo compressor blades are covered with this oily gunk. Yuck! Unfortunately, the EPA emission requirements for the 2007 and up 6.7L diesel Ram tightened up and even they have to run a closed crankcase now. That sucks. I'm glad I got the earlier 5.9 engine in mine. Keep this in mind if you are ever looking for a diesel truck to pull your toys to the track.
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