Step 2. Carbon Build-Up, Diagnosis

Visually inspect the intake valves and ports for carbon build-up as follows:

Cylinder to be checked has to be at top dead center (on compression stroke).

^ remove either right or left side intake manifold

^ using inspection mirror and flex-light, determine degree of carbon build-up on intake valves (through intake ports)

^ compare your observation with chart

^ reinstall intake manifold with new gasket