This paper is concerned with an original method for spark-ignition (S.I.) e
ngine idle improvement. It is well known that inappropriate idle-speed cont
rol increases fuel consumption and pollutant emissions, and also compromise
s stability. The solution proposed here has the distinctive feature of comb
ining the traditional airflow rate control simultaneously with the usual au
tomobile alternator operating as a synchronous motor, to provide a fast sup
plementary torque. Experimental validation is made on a production engine.
The new strategy is compared with the standard one in terms of stability, c
onsumption and pollution. (C) 1998 Published by Elsevier Science Ltd. AII r
ights reserved.