What is MCCC Treatment?

MCCC = Mopar Combustion Chamber Cleaner
Seafoam is another brand of Combustion Chamber Cleaner

A combustion chamber cleaner cleans carburetors, intake manifolds, intake and exhaust valves, pistons and combustion chambers. It also removes deposits, eliminates carbon knock and restores performance.

Some people swear by it, others are on the fence. YMMV.

Short Description of how to use MCCC

Mopar Combustion Chamber Cleaner/Conditioner is really good for removing carbon deposits, but the directions on the can are not so useful. The following directions outline the way that professional mechanics have been using the cleaner for years -- they were finally published in TSB 18-31-97 for 1996-98 Jeep 4.0 Liter misfire conditions:

De-carbonizing Procedure

1. Operate the vehicle until the vehicle reaches operating temperature.
2. Remove the air tube from the throttle body.
3. With the engine at an idle, spray the entire contents of Mopar Combustion Cleaner, p/n 04318001, directly into the throttle body. Allow the vehicle to load up with the cleaner to the point of almost stalling out.
4. Shut the engine OFF after the entire can is ingested.
5. With the hood closed and the vehicle parked inside the garage, allow the vehicle to soak for two to three hours. This will ensure that the engine will maintain its temperature and will allow proper solvent penetration.
6. Drive the vehicle on a highway/freeway that will allow the vehicle to be driven safely at the posted speed limit. Upon entering the highway/freeway, accelerate hard to the posted speed limit and maintain speed. Slow down and then perform 5 to 10 Wide Open Throttle (WOT) upshifts. Continue driving at the maximum speed limit for 1-2 miles (if conditions allow).