Experimental Investigation to Analyze the Effects of Oil Dilution on Unintended Acceleration in a Diesel Engine

Abstract

Due to the gradual reinforcement of emission regulations, exhaust gas after-treatment systems have become more complicated, and various engine control algorithms have been applied to diesel engines. However, the misuse of advanced exhaust gas after-treatment systems could cause additional problems. For instance, diesel vehicles that use of a diesel particulate filter (DPF) generally require periodic active regeneration. While operating active regeneration by in-cylinder post-injection, the fuel impinging on the cylinder wall would become the cause of oil dilution. Furthermore, if, in the event of excessive oil dilution, engine oil overflows in the engine oil pan, engine stalling or unintended acceleration (engine over-run) can occur, as lube oil flows into the combustion chamber through the intake manifold. The present study tested engine overrun by overflowing engine oil diluted with fuel on various engine operating conditions and clarify the engine control factors effect on engine stalling or unintended acceleration using regression analysis. Vehicle tests based on engine test analysis were also conducted to evaluate and reproduce the influence of unintended acceleration by automotive lube oil backflow in real driving. Vehicle test results indicate that unintentional acceleration could occur due to oil dilution, which put the driver at risk.