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P0300, P0301, P0302, P0303, P0304 MISFIRE EC-941 < DTC/CIRCUIT DIAGNOSIS > [MR EXCEPT FOR NISMO RS MODELS] C D E F G H I J K L M A EC N P O P0300, P0301, P0302, P0303, P0304 MISFIRE DTC Logic INFOID:0000000012198439 DTC DETECTION LOGIC When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the crank- shaft position (CKP) sensor (POS) signal to vary, ECM can determine that a misfire is occurring. The misfire detection logic consists of the following two conditions. On the 1st trip, when a misfire condition occurs that can damage the three way catalyst (TWC) due to overheating, the MIL will blink. When a misfire condition occurs, the ECM monitors the CKP sensor signal every 200 engine revolutions for a change. When the misfire condition decreases to a level that will not damage the TWC, the MIL will turn off. If another misfire condition occurs that can damage the TWC on a second trip, the MIL will blink. When the misfire condition decreases to a level that will not damage the TWC, the MIL will remain on. If another misfire condition occurs that can damage the TWC, the MIL will begin to blink again. 2. Two Trip Detection Logic (Exhaust quality deterioration) For misfire conditions that will not damage the TWC (but will affect vehicle emissions), the MIL will only light when the misfire is detected on a second trip. During this condition, the ECM monitors the CKP sen- sor signal every 1,000 engine revolutions. A misfire malfunction can be detected on any one cylinder or on multiple cylinders. DTC CONFIRMATION PROCEDURE 1. PRECONDITIONING If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test. 1. Turn ignition switch OFF and wait at least 10 seconds. 2. Turn ignition switch ON. 3. Turn ignition switch OFF and wait at least 10 seconds. >> GO TO 2. 2. PERFORM DTC CONFIRMATION PROCEDURE-I 1. Start engine and warm it up to normal operating temperature. 2. Turn ignition switch OFF and wait at least 10 seconds. 3. Restart engine and let it idle for following time. 4. Check 1st trip DTC. Sensor Input signal to ECM ECM function Crankshaft position sensor (POS) Engine speed On board diagnosis of misfire DTC No. Trouble diagnosis name (Trouble diagnosis content) DTC detecting condition Possible cause P0300 MULTI CYL MISFIRE Multiple cylinder misfire. • Improper spark plug About 15 minutes |