The process of walnut blasting, which entails cleaning the intake manifold and valves of a car’s engine with a high pressure air blast of finely crushed walnut shells (a biodegradable abrasive), ...

Walnut blasting a good—if expensive, as the intake manifold has to come off—way to maintain engine performance for the life of a direct-injection car.

HOT ROD Top Pick: Berryman Intake Valve & Combustion Chamber Cleaner and B-12 Chemtool Total Fuel System Clean-Up We explain why all gasoline engines, especially direct-injected engines, benefit ...

2. Which way is better, walnut blasting or chemical? - Jess ica Direct injection engines, such as in your Tiguan, suffer from excessive carbon buildup on the backside of the intake valves.

This lack of fuel cleaning additive at the valves and ports leads to more combustion deposits over time. The walnut shell blaster is used once the intake manifold is removed to blast off any deposits.