| 摘要 |
Malfunctions in an exhaust gas recirculation system, particularly on manual transmission vehicles which may be accelerated during a startup period with a rapid succession of upshifts during which exhaust gas recirculation is suspended, is detected from the output of a thermistor positioned on the passageway of the recirculating exhaust gas. In order to allow for the unavoidable delay in gas temperature measurement by the thermistor, a prescribed length of delay time is set up on commencement of exhaust gas recirculation as manifested by the fact that a predetermined set of engine operating conditions have all become satisfied. During the delay time, periods during which exhaust gas actually recirculates are cumulatively summed up, and the sum is compared upon lapse of the delay time with a reference time which is less than the delay time. A possible malfunction in the exhaust gas recirculation system is detected on the basis of the maximum temperature of the recirculating exhaust gas only in cases where the sum is not less than the reference time. A warning will be given if the maximum gas temperature is found not more than a predetermined limit value. |
