Abstract: A fuel property determination apparatus for an internal combustion engine is applied to an internal combustion engine that is equipped with an ignition plug and an ignition timing controller. An electronic control unit provided in the fuel property determination apparatus executes a determination process of making a determination on a property of a fuel supplied to the internal combustion engine based on an ignition sufficiency ratio, during a predetermined period after startup of the internal combustion engine. The electronic control unit is configured to determine that the property of the fuel is heavy when a determination index value that is obtained by subjecting the ignition sufficiency ratio to a smoothing process is equal to or larger than a predetermined threshold. The electronic control unit is configured to set a smoothing coefficient to a value corresponding to each of a first period, a second period, and a third period.

Abstract: A apparatus for an engine, and the apparatus includes an ECU. The ECU is configured to (i) perform a feedback control such that the engine speed converges to a target speed by correcting ignition timing during the feedback control, (ii) make a determination that fuel supplied to the engine is a heavy fuel when an ignition fulfillment rate is equal to or greater than a predetermined threshold value within a predetermined period after the engine is started, the ignition fulfillment rate is a ratio of the advance correction amount of the ignition timing to a maximum ignition correction range, the maximum ignition correction range is a maximum range in which the ignition timing is corrected during the feedback control, and (iii) set the threshold value to a value that depends on a temperature representative value of the engine, the temperature representative value is correlated with the engine temperature.

Abstract: A apparatus for an engine, and the apparatus includes an ECU. The ECU is configured to (i) perform a feedback control such that the engine speed converges to a target speed by correcting ignition timing during the feedback control, (ii) make a determination that fuel supplied to the engine is a heavy fuel when an ignition fulfillment rate is equal to or greater than a predetermined threshold value within a predetermined period after the engine is started, the ignition fulfillment rate is a ratio of the advance correction amount of the ignition timing to a maximum ignition correction range, the maximum ignition correction range is a maximum range in which the ignition timing is corrected during the feedback control, and (iii) set the threshold value to a value that depends on a temperature representative value of the engine, the temperature representative value is correlated with the engine temperature.

Abstract: A fuel property determination apparatus for an internal combustion engine is applied to an internal combustion engine that is equipped with an ignition plug and an ignition timing controller. An electronic control unit provided in the fuel property determination apparatus executes a determination process of making a determination on a property of a fuel supplied to the internal combustion engine based on an ignition sufficiency ratio, during a predetermined period after startup of the internal combustion engine. The electronic control unit is configured to determine that the property of the fuel is heavy when a determination index value that is obtained by subjecting the ignition sufficiency ratio to a smoothing process is equal to or larger than a predetermined threshold. The electronic control unit is configured to set a smoothing coefficient to a value corresponding to each of a first period, a second period, and a third period.