Cold start fuel management of port-fuel-injected internal combustion engines

Abstract

The purpose of this study is to investigate how changes in fueling strategy in the second cycle of engine operation influence the delivered charge fuel mass and engine out hydrocarbon (EOHC) emissions in that and subsequent cycles. Close attention will be paid to cycle-to-cycle interaction of the fueling strategy. It is our intent to see if residual fuel from each cycle has a predicable influence on subsequent cycle's charge mass and EOHC emissions. The fast flame ionization detector is employed to measure both in-cylinder and engine out hydrocarbon concentrations for various cold start strategies. The manufacturer's original fueling strategy is used as a starting point and is compared to a "in-cylinder fuel air ratio (Phi) [approx.] 1" case (a fueling strategy that results in an in-cylinder concentration of approximately stoichiometric for each of the first five cycles) and to a number of cases that are chosen to illustrate cycle-to-cycle mixture preparation dependence on second cycle fueling. Significant cycle-to-cycle dependence is observed with the change in second cycle. A fueling deficit in cycle two has a more pronounce effect on future cycles delivered charge mass than a fueling surplus while a fueling surplus in cycle two has a more pronounce effect on future cycles charge mass than a fueling deficit.