2005 - Mazda6 - Workshop Manual - Engine DTC P0300 [L3] DTC P0300 Random misfire detection PCM monitors CKP sensor input signal interval time. PCM calculates the change of the interval time for each cylinder. If the change of interval time exceeds the preprogrammed criteria, PCM detects a misfire in the corresponding cylinder. While the engine is running, PCM counts the number of misfires that occurred at 200 crankshaft revolutionsand 1,000 crankshaft revolutionsand calculates misfire ratio for each crankshaft revolution. If the ratio exceeds the preprogrammed criteria, PCM determines that a misfire, which can damage the catalytic converter or affect emission performance, has occurred. Diagnostic support note This is a continuous monitor (Misfire). DETECTION CONDITION MIL illuminates if PCM detects the misfire which affects emission performance in two consecutive drive cycles or in one drive cycle while DTC for the same malfunction has been stored in PCM. PENDING CODE is available if PCM detects the misfire which affects emission performance during first drive cycle. MIL flashes if PCM detects the misfire which can damage the catalytic converter during first drive cycle. FREEZE FRAME DATA is available. DTC is stored in the PCM memory. POSSIBLE CKP sensor malfunction CAUSE CMP sensor malfunction Ignition coil malfunction High-tension lead malfunction *2 Ignition system malfunction MAF sensor contamination Excess air suction in intake air system (between MAF sensor and intake manifold) Fuel pump malfunction Fuel pressure regulator malfunction Clogged fuel line Clogged fuel filter Fuel leakage in fuel line Fuel run-out Poor quality fuel Purge control solenoid valve malfunction PCV valve malfunction EGR valve malfunction Vacuum hose damage or improper connection Related connector and terminal malfunction Related wiring harness malfunction Insufficient compression Variable valve timing control system improper Diagnostic procedure STEP INSPECTION ACTION 1 VERIFY FREEZE FRAME DATA AND YesGo to the next step. DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED No Record FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST Have FREEZE FRAME DATA RESULTS on repair order, then go to the next and DIAGNOSTIC step. MONITORING TEST RESULTS (Misfire related) been recorded? 2 VERIFY RELATED REPAIR INFORMATION YesPerform repair or diagnosis according to the AVAILABILITY available repair information. Check for related Service If the vehicle is not repaired, Bulletins and/or on-line repair go to the next step. information availability. Is any related repair information available? No Go to the next step. 3 VERIFY RELATED PENDING CODE OR YesGo to appropriate DTC troubleshooting. STORED DTCs (See DTC TABLE [L3].) Turn ignition switch to OFF, then ON (Engine off). Verify related PENDING CODE or stored DTCs. Are other DTCs present? No Go to the next step. 4 VERIFY CURRENT INPUT SIGNAL STATUS YesInspect suspected circuit and/or part according to (ignition switch TO ON/IDLE) inspection results. Access APP1, APP2, ECT, IAT, (See PCM INSPECTION [L3].) MAF, RPM, TP_REL, and VSS PIDs using the WDS or Then go to Step 24. equivalent. No Go to the next step. (See PCM INSPECTION [L3].) Is there any signal that is far out of specification when ignition switch is ON and engine runs at idle? 5 VERIFY CURRENT INPUT SIGNAL STATUS YesInspect suspected circuit and/or part according to UNDER TROUBLE CONDITION inspection results. Inspect same PIDs as in Step 4 (See PCM INSPECTION [L3].) while simulating FREEZE FRAME DATA condition. Then go to Step 24. Is there any signal which causes drastic changes? No Go to the next step. 6 INSPECT CMP SENSOR YesGo to the next step. No Inspect installation condition and damage on Inspect CMP sensor. timing chain and gears, repair faulty parts. (See CAMSHAFT POSITION If it is normal, replace CMP (CMP) SENSOR INSPECTION sensor. [L3].) Then go to Step 24. Is CMP sensor normal? 7 VERIFY CKP SENSOR INSTALLATION YesRetighten CKP sensor, then go to Step 24. CONDITION No Go to Step 12. *1 Inspect for CKP sensor looseness. Go to the next step. *2 Is CKP sensor loose? 8 INSPECT IGNITION COIL OPERATION AND YesGo to Step 14. HIGH-TENSION LEAD WITH TIMING LIGHT Verify blinking condition on each cylinders using timing light at idle. No Go to the next step. Do all cylinders show blinking condition? 9 INSPECT HIGH-TENSION LEADS OF NO YesGo to the next step. BLINKING CYLINDER Turn the ignition switch off. Inspect high-tension leads for No Replace faulty high-tension lead, then go to Step improper installation, corrosion 24. on terminal, open lead and damaged cover. Is condition of high-tension lead normal? 10 INSPECT POWER SUPPLY TERMINAL AT YesGo to the next step. IGNITION COIL CONNECTOR Disconnect ignition coil connector. No Inspect for open circuit between ignition coil connector and ignition switch. Repair or replace Turn ignition switch to ON wiring harness, then go to Step 24. (Engine off). Measure voltage between ignition coil terminal B (harness-side) and body ground. Is voltage B+? 11 INSPECT IGNITION COIL RESISTANCE YesGo to step 24. Inspect ignition coil resistance. (See IGNITION COIL No Replace ignition coil, then go to Step 24. INSPECTION.) Is coil resistance normal? 12 INSPECT IGNITION COIL HARNESS YesGo to the next step. Inspect the ignition coil related harness condition (intermittent No Repair suspected wiring harnesses, then go to open or short) for all cylinders. Step 24. Are harness conditions normal? 13 INSPECT IGNITION SYSTEM OPERATION YesGo to the next step. Carry out Spark Test. No Repair or replace malfunctioning part according (See Spark Test (California to Spark Test result. Emission Regulation Applicable ATX Model). Spark Test (Except Then go to Step 24. for California Emission Regulation Applicable ATX Model).) Is strong blue spark visible at each cylinder? 14 INSPECT MAF PID YesGo to the next step. No Replace MAF sensor, then go to Step 24. Start engine. Access MAF PID using the WDS or equivalent. Verify that MAF PID changes quickly according to race engine RPM. Is MAF PID response normal? 15 INSPECT EXCESSIVE AIR SUCTION IN YesRepair or replace suspected part, then go to Step INTAKE AIR SYSTEM 24. Inspect for air leakage at following: Between MAF sensor and throttle body Between throttle body No Go to the next step. and intake manifold Is there any malfunction? 16 INSPECT FUEL LINE PRESSURE YesGo to Step 18. No If fuel line pressure is too low, go to the next Inspect fuel line pressure. step. (See FUEL LINE PRESSURE If fuel line pressure is excess high, replace fuel INSPECTION.) pump unit, Is fuel line pressure normal? then go to Step 24. 17 INSPECT FUEL LINE FROM FUEL PUMP TO YesReplace suspected fuel line, then go to Step 24. FUEL DELIVERY PIPE No Inspect low-pressure side fuel filter for following: Visually inspect for fuel leakage in fuel line for any leakage. Foreign materials or stain inside fuel filter Is any fuel leakage found? Perform following actions depend on the result above. If foreign materials or stain is found inside fuel filter (low- pressure side), clean of fuel tank and filter (low-pressure side). If normal, replace fuel pump unit. Then, go to Step 24. 18 INSPECT ENGINE COMPRESSION YesGo to the next step. Inspect engine compression. No Implement engine overhaul for repairs, then go (See COMPRESSION to Step 24. INSPECTION [L3].) Is it normal? 19 INSPECT VARIABLE VALVE TIMING YesGo to the next step. CONTROL SYSTEM OPERATION Inspect variable valve timing No Repair or replace malfunctioning part according control system operation. to variable valve timing control system inspection results, then go to Step 24. (See Variable Valve Timing Control System Operation Inspection.) Does variable valve timing control system work properly? 20 INSPECT OPERATION OF PURGE CONTROL YesGo to the next step. SOLENOID VALVE Inspect purge control system No Repair or replace malfunctioning part according operation. to purge control system inspection results, then go to Step 24. (See Purge Control System Inspection.) Does purge control system work properly? 21 INSPECT PCV VALVE OPERATION YesReplace PCV valve, then go to Step 24. No Go to the next step. Turn the ignition switch off. Remove PCV valve and inspect valve operation. (See POSITIVE CRANKCASE VENTILATION (PCV) VALVE INSPECTION [L3].) Is PCV valve operation normal? 22 INSPECT OPERATION OF EGR VALVE YesRepair or replace EGR valve, then go to Step 24. Remove EGR valve. Visually inspect for stuck to open. No Go to the next step. Is EGR valve stuck to open? 23 INSPECT SEALING OF ENGINE COOLANT YesAir gets in from poor sealing on head gasket or PASSAGE other areas between combustion chamber and engine coolant passage. Repair or replace faulty WARNING: parts, then go to the next step. Removing radiator cap when radiator is hot is dangerous. Scalding coolant and steam may shoot out and cause serious injury. When removing radiator cap, wrap thick cloth around and turn it slowly. Remove radiator cap. Implement procedure to bleed air from engine coolant, then run engine at idle. Is there any small bubble which makes engine coolant white at filling opening? NOTE: Large bubbles are normal since they are No Go to the next step. remaining air coming out from engine coolant passage. 24 VERIFY TROUBLESHOOTING OF MISFIRE YesReplace PCM, then go to the next step. DTC COMPLETED (See PCM REMOVAL/INSTALLATION [L3].) Make sure to reconnect all disconnected connectors. Turn ignition switch to ON (Engine off). Clear the DTC from the memory using the WDS or equivalent. Start engine and perform DRIVE MODE 1. (See OBD-II DRIVE MODE No Go to the next step. [L3].) Is PENDING CODE for this DTC present? 25 VERIFY AFTER REPAIR PROCEDURE YesGo to the applicable DTC inspection. Perform the “After Repair (See DTC TABLE [L3].) Procedure”. (See AFTER REPAIR PROCEDURE [L3].) No Troubleshooting completed. Is any DTC present?.