Method and apparatus for determining state of reformer

摘要

An internal combustion engine includes a reformer for reforming a fuel air mixture to produce a reformed gas, a crank angle sensor for detecting a rotational speed of the engine, and an ECU. The ECU obtains a difference of an actual rotational speed from a target rotational speed of the engine during an idling thereof based on a signal from the crank angle sensor. When the difference thus obtained exceeds a predetermined threshold value, the ECU determines that a reforming catalyst of the reformer has deteriorated or there is any abnormality in the reformer.