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Home >> Saab >> 2000 >> 9-3 Base, 2D Convertible, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - TRIONIC T7 Fuel Control System >> Diagnostic Tests >> DTC P1300: Random Misfire Detected, Potential Catalyst Damage

DTC P1300: Random Misfire Detected, Potential Catalyst Damage

  1. Connect TECH 2 scan tool to Data Link Connector (DLC). Turn ignition on. Check and make note of scan tool ENGINE SPEED, AIR MASS/COMBUSTION and COOLANT TEMPERATURE freeze frame data for DTC P1300. Check for any stored DTCs. If DTC P0171, P0172, P1171, P1172, P1181, P1182, P1641 or P1676 is present, go to appropriate diagnostic test procedure. If no DTCs are present, go to next step.
  2. Check all hoses and intake system components between turbocharger and throttle body. Inspect vacuum hose between intake manifold and fuel pressure regulator. Repair any leaks found. Check scan tool COOLANT TEMPERATURE value and compare to actual engine temperature. If temperature indicated is substantially different than actual engine temperature, diagnose and repair any electrical circuit problems found. Go to next step.
  3. Check engine compression. Replace spark plugs. See SPARK PLUGS under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION article. If any mechanical problems are found, repair as necessary and go to step  10. If engine compression readings are okay, go to next step.
    WARNING: Ignition discharge module (IDM) can discharge in excess of 40,000 volts. Ensure that spark plugs are properly grounded, and keep adequate distance from IDM while conducting following test.
  4. Test ignition discharge module (IDM) operation. See IGNITION DISCHARGE MODULE (IDM) under MODULES, RELAYS & SOLENOIDS in appropriate SYSTEM & COMPONENT TESTING article. If any ignition coil does not operate as specified, replace IDM and go to step  10. If all coils operate as specified, go to next step.
  5. Connect TECH 2 scan tool to Data Link Connector (DLC). Turn ignition on. Check and compare values for ATMOSPHERE ABSOLUTE PRESSURE, CHARGE AIR ABSOLUTE PRESSURE and MANIFOLD ABSOLUTE PRESSURE sensors. All 3 sensors should show a value of about 100 kPa at sea level. If any sensor differs by more than 10 kPa from the others, replace pertinent sensor. See Figure for EVAP canister purge valve, ECM and sensor locations. See ENGINE CONTROL MODULE (ECM) under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article. Go to next step.
    NOTE: Atmosphere absolute pressure sensor is inside ecm and cannot be replaced separately.
  6. Test drive vehicle in high gear with steady high engine load, preferably uphill. Use scan tool to select READ VALUE: AIRMASS DEVIATION FROM CALCULATED VALUE. If deviation is between -15 percent and -25 percent, check for air leak in intake system and repair as necessary. If no leaks are found, replace MAF sensor. Go to step  10. If deviation is not as specified, go to next step.
  7. Inspect fuel system. See FUEL PRESSURE, FUEL PUMP FLOW and FUEL INJECTORS under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If any fuel system problems are found, repair as necessary. Go to next step.
  8. Use scan tool to clear DTCs. Disconnect EVAP canister purge valve electrical connector. Connect test light between purge valve harness connector terminals No. 1 and 2. Start engine and allow it to idle until coolant temperature exceeds 140°F (60°C). Use scan tool to select READ VALUE: PURGE ADAPTATION. If value displayed is -15 percent to +15 percent, go to next step. If value displayed is not as specified, problem is still present.
  9. Reconnect EVAP canister purge valve electrical connector. Test drive vehicle at a steady speed between 37-62 mph. Use scan tool to select READ VALUE: MULTIPLICATIVE ADAPTATION. Observe reading until it changes, then stop vehicle and leave engine running. If reading eventually stabilizes between -15 percent and +15 percent, clear all system DTCs and go to next step. If reading does not stabilize as specified, problem is still present.
  10. Use scan tool to select ACTIVATE: RESET MISFIRE AND KNOCK COUNTERS. Test drive vehicle and monitor current readings for MISFIRE CYL 1-4. During test drive, duplicate previously noted freeze frame values for ENGINE SPEED, AIR MASS/COMBUSTION and COOLANT TEMPERATURE. If any misfire/knock counters are incrementing continuously, problem is still present. If no counters are incrementing continuously, go to next step.
    NOTE: A few misfires are acceptable as long as counter is not incrementing at a continuous rate.
  11. Use scan tool to check if DTC P0420 has been stored. If DTC P0420 is present, go to next step. If DTC P0420 is not present, test drive vehicle at varying speeds for 5 minutes under the following conditions: do not allow engine to idle for more than 40 seconds, and do not allow engine to brake vehicle with released brake pedal for more than 10 seconds. Afterwards, test drive vehicle on level ground for 1 minute between 43-56 MPH. Check scan tool display for diagnostic status of DTCs. If scan tool display reads OK, clear all system DTCs. If scan tool reads NOT READY, back up to INITIATING DIAGNOSTICS and recheck DTC status. If scan tool shows DTC P1300, go to next step.
  12. Replace catalytic converter and use scan tool to clear all system DTCs.
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