What?s the easiest way to clean the intake valves on my GDI Engine? GDI engine intake valves are prone to deposit build up because they never get washed with fuel. Now there is an easy way to clean your GDI intake valves without having to disassemble the top of the engine. Use CRC GDI IVD Intake Valve Cleaner. To use it, start the engine and get it up to operating temperature. Locate the Mass Air Flow Sensor, and use the attached PERMASTRAW to insert the product past the Mass Sensor, directly into the air intake. This will help you to avoid throwing any codes. CRC Intake Valve Cleaner reaches the back of the valves at 150 times the concentration of any premium fuel additive, and is proven to remove up to 23% of carbon buildup in just the first hour. This tip is brought to you by CRC Industries, the makers of Brakleen the number one brake parts cleaner.