Search Results

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.

A Pore Fuel Injector Deposit (PFID) test has been developed which provides repeatable results. The test can discriminate gasolines with differing fuel injector fouling tendencies in vehicles. Results confirm previous work that added mono-and diolefins increase deposit growth. The test is also able to evaluate the performance of additives. Other factors found to affect injector deposit formation include: injector soak temperature, injector soak pressure, weeping vs non-weeping injectors, and the presence of oxygen around the injector pintle. The PFID test can be run in about one quarter the time needed to evaluate fuels in vehicle and dynamometer tests.(1)