Characterization of Intake Valve Deposits Including Thermal Resistance Effects

Intake valve deposits were characterized by chemical composition, thickness, density, porosity, hardness, and heat transfer effects. Data are presented to support the theory that high-load accelerations create deposits that may be primarily fuel related. A method to determine deposit thicknesses using a coordinate measuring machine is described. A finite element heat transfer analysis was undertaken to predict temperatures, estimate deposit thermal resistance, and demonstrate a method for modeling transient heating. The fuel-absorbing characteristic of deposits is examined in relation to warm-up driveability problems. Vehicle tests were performed to investigate the thermal resistance effect of deposits to poor driveability.