I'll start with a little back-story as to why I'm tearing the motor apart...
Back on July 31, I was leaving for work that morning when the idle became extremely rough (but idle speed remained a constant 750 RPM). I shut the car off, started again with same rough idle issue. Eventually the car completely stalled and would not even crank. So, after waiting two days for it to arrive I replaced original battery with the MTP-91. Same issue, rough idle. Cranked every time without hesitation, and would run perfect during the warmup idle (initial 5-10 seconds) and once the idle settled into its normal lope, the car started sputtering again. Got the BAS/ESP code and also a check engine light. Strong smell of unburnt fuel.
So, I called AAA and had it taken to the local indie-shop for Mercedes vehicles. Using the Autologic scanner, they found P0105 code (MAP/pressure sensor fault). They cleared the codes, including BAS/ESP. Started it up and ran perfectly. With my permission, they spent about 30 minutes driving it to see if the condition would repeat itself. It seemed all was well, as the car was idling perfectly. I took the car home on August 14 and it ran flawlessly. Installed DCAI on 8/18, car ran even stronger (obviously). Tuesday, August 22, I go out to make a quick errand and -- guess what -- rough idle is back. STRONG fuel smell, sputtering idle, but idle RPMS are still a constant 750 RPM). So, naturally I'm thinking MAP sensor. I researched the P0105 code on MB-World in the C32 section and saw dozens of posts describing a rough idle similar to mine.
So I'm pulling the manifolds yesterday to replace the MAP sensor. MAP sensor is located just at the rear of the intercooler, right in front of the Y-pipe.
As I remove the L/H mani, I look inside and see oil. Waaaaaay too much oil IMO. It's not green, like it would be with the typical intercooler failure. BUT, the previous owner changed the coolant, so it's no longer the OE blue, but rather an orange coolant.
I cleaned the manis with a degreaser and was able to remove most of it. The residue that is shown in the photos had a texture similar to guacamole dip -- oily, but light.
Noteworthy that I have the Needswings catch can. I drained it last night, and since my last oil change (2 months ago) I got about an ounce of oil out of the can. So, it's nowhere near full.
Also noteworthy, I have an unseparated h/e with the Johnson CM30. So it's a high-pressure system.
Does this look like a typical intercooler failure? I only have 52,000 on the car. If so, would this have caused the MAP sensor failure? After all, the MAP sensor is nothing but a nipple that is inserted into the intercooler, and if this gets clogged, it won't read properly.
Ironically, yesterday when I cranked the car to move it back a foot (to allow me to fully open the hood in the garage) the car cranked right up and idled perfectly. The previous 10 starts all had a rough idle.
Advice appreciated.