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Home >> Saab >> 2000 >> 9-3 Base, 2D Convertible, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - TRIONIC T7 Fuel Control System >> Diagnostic Tests >> DTC P1390: Random Misfire & Low Fuel Level Detected - Possible Catalyst Damage

DTC P1390: Random Misfire & Low Fuel Level Detected - Possible 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 P1390. Check for any stored DTCs. If DTC P0171, P0172, P1171, P1172, P1181, P1182 or P1641 is present, go to appropriate diagnostic test procedure. If DTC P1676 is present, go to next step. If no DTCs are present, go to step  5.
    NOTE: If you are returning back to this procedure from DTC P0171, continue at step  6.
  2. Inspect fuse No. 16B in dashboard fuse block and replace if necessary. See Figure. Connect TECH 2 scan tool to Data Link Connector (DLC). Turn ignition on. Select ACTIVATE: FUEL INJECTORS. Operate each injector one at a time and listen for a ticking sound from each injector. If no injectors can be heard at all, check for faulty circuit between fuse No. 16B and spliced crimp connection J34 located in engine wiring harness (Green/Red wire). See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary and go to step  5. If one injector can not be heard, go to next step.
  3. Disconnect harness connector from suspect fuel injector. Connect SST 86 11 857 test light (see Figure) or equivalent between fuel injector harness connector terminal No. 1 (Green/Red wire) and ground. See Figure. If test light illuminates, go to next step. If test light does not illuminate, check for faulty circuit between suspect fuel injector harness connector terminal No. 1 and spliced crimp connection J34. Repair as necessary and go to step  5.
  4. Connect both test light leads to fuel injector harness connector terminals No. 1 and 2. Use scan tool to select ACTIVATE: FUEL INJECTOR. If test light does not illuminate, repair faulty circuit between pertinent fuel injector harness connector terminal No. 2 and following ECM harness connector terminal:
    • Cylinder No. 1: terminal No. 45 (Green/Black wire).
    • Cylinder No. 2: terminal No. 44 (Green/White wire).
    • Cylinder No. 3: terminal No. 67 (Purple/White wire).
    • Cylinder No. 4: terminal No. 68 (Grey/White wire).
    See Figure for ECM location. See Figure for ECM terminal identification. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light does illuminate, replace faulty fuel injector. See FUEL INJECTORS under FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article. Repair as necessary. Go to next step.
  5. 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, recheck for presence of previously listed DTCs at beginning of this procedure. If any DTCs are present, go back to start of this diagnostic procedure. If DTCs are not present, go to next step. If no counters are incrementing continuously, problem may have been caused by a low fuel level. Go to step  16.
    NOTE: A few misfires are acceptable as long as counter is not incrementing at a continuous rate.
  6. Check and make note of scan tool ENGINE SPEED, AIR MASS/COMBUSTION and COOLANT TEMPERATURE freeze frame data for DTC P1390. Check all hoses and intake system components between turbocharger and throttle body. Inspect vacuum hose between intake manifold and fuel pressure regulator. Check scan tool COOLANT TEMPERATURE value and compare to actual engine temperature. Repair any leaks or electrical circuit problems found. Go to next step.
  7. Check engine compression and 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  15. If engine compression readings are okay, go to next step.
  8. 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  15. If all coils operate as specified, go to next step.
  9. 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 or Figure for 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.
  10. 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, replace MAF sensor and go to next step. If deviation is not as specified, go to step  12.
  11. 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, clear all system DTCs and go to step  16.
    NOTE: A few misfires are acceptable as long as counter is not incrementing at a continuous rate.
  12. Inspect fuel system. See FUEL PRESSURE, FUEL PUMP FLOW and FUEL INJECTORS under FUEL SYSTEM FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If any fuel system problems are found, repair as necessary. Go to next step.
  13. Turn ignition on. Use scan tool to clear DTCs. Unplug EVAP canister purge valve harness connector. Connect test light to both terminals of purge valve harness connector to prevent DTC from setting during testing. Start engine and allow it to idle until coolant temperature exceeds 140°F (60°C). Set scan tool to READ VALUE: PURGE ADAPTATION. If scan tool value is between -15 percent and +15 percent, go to next step. If scan tool value is not as specified, turn ignition off and remove test light. Reconnect purge valve harness connector. Problem is still present.
  14. Turn ignition off and remove test light. Reconnect purge valve harness connector. Test drive vehicle between 37-62 mph between 1500-2750 RPM with constant throttle. Read MULTIPLICATIVE ADAPTATION value. Wait until reading changes, then change speed or stop if desired. Wait until scan tool reading stabilizes. If scan tool value is between -15 percent and +15 percent, system is operating normally. Clear all system DTCs. For DTC P0301-P0304, go to next step. If scan tool value is not as specified, problem is still present.
  15. 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. Restart diagnostic procedure. 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.
  16. Use scan tool to check if DTC P0420 has been stored. If DTC P0420 is present, replace catalytic converter and clear all system DTCs. 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 displays pertinent DTCs, replace catalytic converter and clear all system DTCs.
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