Walnut Blasting is a factory recommended service for BMW and MINI owners every 30,000 miles.

You may think your BMW is in need of a Tune Up, but it could be more than that.

As your BMW or Mini approaches 30,000 miles, and certainly at the 60,000 mileage mark, your BMW* will most likely experience carbon build-up on the Intake Valves of your direct injection engine*. This build-up affects the way air enters the combustion chamber, causing many symptoms, which can include misfiring, rough running, hard starting, and poor fuel economy.

If that were not enough, the likelihood of a burnt valve is greatly increased,  and will cost much more to repair in the long run.

BMW Intake Valve Carbon Cleaning

Causes of Direct Injection Carbon Build-Up

In the ongoing effort by car manufacturers to improve performance, and mileage, they have made some advances to the design of the fuel injection, and emission control systems used in many of todays modern engines.

One major modification is that they have moved (changed the location) of the fuel injector from the intake
manifold, to directly in the cylinder (combustion chamber). This design is referred to as a “direct injected engine” and has many performance gains.

Previously, the fuel injectors used to be in the intake manifold, close to the intake valves of the engine. With this design the injector would spray the fuel past the valve and it would act like a cleaning agent and clean or prevent oil and carbon deposits from accumulating on the intake valves.

Why is there carbon and oil on the intake valve in the first place?

In addition to the intake valves becoming coated  with solid carbon deposits, with the continued evolution of the emissions systems, one of the techniques is to divert the crankcase fumes, generally referred to as “Blow-By”* and re-direct them into the intake manifold to allow them to be mixed as part of the combustion process, therefore ensuring the fumes don’t vent to atmosphere.  They then go thru the catalytic convertors to get cleaned  before exiting the exhaust system and entering the atmosphere. The combination of these two designs has caused the intake valves to now become a collector of oil and carbon deposits.