DTC P0300 - Random Misfire Detected
NOTE:
For terminal identification, see TERMINAL IDENTIFICATION in SELF-DIAGNOSTICS section. For circuit and wire color identification, see WIRING DIAGRAMS - 2.4L
article.
- Connect external tachometer. Using scan tool in MUT II mode, read SERVICE DATA No. 22 (crankshaft position sensor). Check engine RPM during cranking and at idle. If RPM displayed on scan tool and tachometer are equal, go to next step. If RPM displayed on scan tool and tachometer are not equal, go to step 4 .
- Using oscilloscope, perform crankshaft position sensor wave form check. Connect Test Harness MD998478 between Crankshaft Position (CKP) sensor and harness connector. Connect analyzer special patterns pickup to CKP sensor terminal No. 2. If test harness is not available, connect analyzer special patterns pickup to PCM terminal No. 89. Go to next step.
- With engine idle speed stable, compare CKP sensor wave pattern to known-good wave pattern. See Fig 1 . If wave pattern is okay, go to step 5 . If wave pattern is not okay, go to next step.
- Check CKP sensor connector, PCM connector and wiring harness between PCM and CKP sensor connector. Check CKP sensor and sensing plate for proper installation. If wiring, connectors and sensor installation are okay, replace CKP sensor.
- Perform DTC P0301, DTC P0302, DTC P0303 OR DTC P0304 - CYLINDER NO. 1, 2, 3 OR 4 MISFIRE DETECTED . If wiring, connector and injector are okay, go to next step. If wiring, connector or or injector are not okay, repair as necessary.
- Start and warm engine. Turn all accessories off. Increase engine speed to 2500 RPM. Using scan tool in MUT II mode, read SERVICE DATA No. 81 (long-term fuel compensation). If fuel trim is -12.5-12.5 percent (during closed loop), go to next step. If fuel trim is not as specified, check fuel trim fault. See DTC P0170 - FUEL TRIM MALFUNCTION .
- Using scan tool in MUT II mode, read SERVICE DATA No. 21 (engine coolant temperature). If temperature displayed on scan tool is equal to actual Engine Coolant Temperature (ECT), go to next step. If temperature displayed on scan tool is not equal to actual ECT, check ECT circuit. See DTC P0115 - ENGINE COOLANT TEMPERATURE (ECT) CIRCUIT MALFUNCTION .
- Check ignition coil, spark plugs and spark plug wires. Check for broken timing belt teeth. Check compression pressure, and EGR system. See BASIC TESTING - 2.4L article.