Monitoring of the Mixture Strength in the Cylinders of a Port-Injected Gasoline Engine During Transient Operation

Abstract

A method has been developed which allows monitoring of the air—fuel ratio within the cylinders of a running gasoline engine. The method, which uses a fast-response flame ionization detector (FID), is capable of resolving the air—fuel ratio of individual consecutive engine cycles This method was used to monitor the air—fuel ratio in a port-injected gasoline engine during fast throttle opening. The results obtained show that for a handful of engine cycles the air—fuel ratio departs from the stoichiometric Value. Using additional measurements of the air and fuel supplied to the engine, it was possible to investigate the accumulation of fuel on the inlet port walls of the engine during the throttle opening. The results presented in this paper suggest that the departure of the air—fuel ratio from the stoichiometric value is shorter lived than that recorded by other investigators who used exhaust oxygen sensors for their tests.