Circuit Description
Misfire: ECM uses crankshaft position sensor and camshaft position sensor to monitor changes in crankshaft rotation for each cylinder. The ECM counts the number of times engine speed change rate indicates that misfire has occurred. And when misfire rate equals to or exceeds count indicating that engine condition has deteriorated, MIL lights up. If misfire rate is high enough and driving conditions will cause catalyst to overheat, MIL blinks when misfire occurs.
Detecting condition of DTC P0300 is when misfire of random cylinders is detected during any particular 200 or 1000 revolutions. Detection conditions of DTCs P0301-P0304 are:
- For any particular 200 revolutions for engine, misfiring is detected which can cause catalyst overheating (this causes MIL to blink).
- For any particular 1000 revolutions of engine, misfiring is detected which causes a deterioration in emissions (2 trip detection logic).