Reduction of exhaust smoke emissions following extended diesel engine idling

For use with a diesel engine having an exhaust particulate filter, a method of purging said filter of gaseous hydrocarbons and water accumulated in said filter during low load operation of said engine, comprising the steps of;

• (A) sensing when said engine operating at a low load condition;
• (B) determining when said engine has remained in said low load condition for a predetermined period of time by commencing a count from a beginning count value during the time that said engine remains at said low load condition;
• (C) when said period has been determined in step (B), increasing the temperature of the exhaust gas entering said filter to a temperature sufficient to purge said filter of said gaseous hydrocarbons and water;
• (D) sensing the temperature of the exhaust gas exiting said filter;
• and,
• (E) decrementing said time count during the period that said filter is being purged in step (C), such that said time count is continuously related to the magnitude of the gaseous hydrocarbons and water accumulated in said filter;
• (F) when the temperature sensed in step (D) reaches a value indicating that the purge of said filter has been completed, terminating step (C) and resetting said time count to said beginning count value.