Help with cleaning intake
 

I have a 94 e320 110,000 miles

I removed my intake duct that runs over the engine to the throttle body and noticed it has a black film of oil in it and the throttle body is quite dirty. I want to clean these to try and help my surging issues. So after reading for hours here I will perform the following:
-Clean MAF
-Clean Throttle body
-Clean intake duct
-Change plugs to f8dc4
-Change plug connectors under coils
-Clean EGR tube

Some questions:
What do I use to clean the MAF and how?
For the throttle body I read here to use brake cleaner, and then spray with WD40. Is this correct?
How is the oil getting into my intake duct?
Also what is the sensor that plugs into the intake tube before the throttle body and how to clean it?
Do I need to replace the rubber seals that go from the intake duct to the engine?

Thanks for your help.

For MAF, use CRC's air sensor cleaner only.

For the MAF Isopropyl Alcohol spray is perfect. Do not use carb cleaner, and do not touch the sensor wire.

In fact, you can use the alcohol spray to clean everything. It doesn't require wiping off since it will evaporate quickly and leave no residue.

Thanks,

Am I supose to spray the throttle body with wd40 after cleaning?

How is oil getting into the intake tube?

Also what is the sensor the plugs into the intake tube before the throttle body and how to clean it?

If it were my throttle body, I would not spray it with WD40 (or something equivalent), unless this was a specific factory manual instruction. WD40 leaves a residue, and I don't think you want to do that.

The sensor you are asking about is probably an intake air temperature sensor, used by the computer to calculate the density of the air flowing through the intake. Just use the same thing you use for the MAF sensor and rest of the intake.

For MAF cleaning, you can use any no-residue electrical contact cleaner (CRC's MAF sensor cleaner is simply re-labelled electrical contact cleaner.), carb or throttle body cleaner, or brake cleaner. None of the solvents in any of these products will harm the plastics in the MAF.

Oil and other residues from the gasoline are probably coating the intake by evaporating from the cylinders when the hot engine is turned off. Some valves are always open when the engine is off, so the lighter, more volatile components of the oil will evaporate from the hot cylinder and cylinder head surfaces and then travel to the cool intake and condense leaving the oily film.

Cleaning the intake and throttle body is a good routine maintenance item.

Brett

No WD40 ever in the intake.

Brett - Wanted to follow-up with you on how, specifically, you clean the throttle bodies in your V12. Any chance of getting a brief step-by-step for a fellow V12 owner? Thanks in advance.