Experimental study on dynamic misfire characteristics of CI engine during cold start

Highly intensified diesel engines frequently experience dynamic misfire and speed stagnation after the initial cycle ignition during cold start, leading to a significant increase in starting time and unburned hydrocarbon (HC) emissions. This study performs an experimental investigation into the dynamic misfire process of diesel engines, aiming to thoroughly examine the dynamic misfire characteristics and the critical parameter constraints associated with this phenomenon. The investigation focuses on the dynamic ignition characteristics of diesel engine at temperatures of 253K, 263K, and 283K. Results indicate that during cold start, the number of cylinders ignited per cycle is typically centered around partial cylinders to maintain relative rotational speed stability. The alternating occurrence of acceleration and deceleration cycles contributes to speed stagnation. Furthermore, the ignition of the upper cycle in the same cylinder, along with the low rate of rotational speed increase, significantly promotes ignition in the current cycle within the same cylinder. Finally, this study identifies the core factors influencing the dynamic misfire process in diesel engines: the alignment between the ignition delay and the available ignition interval. The validity of this hypothesis is confirmed through the analysis of cylinder pressure data.