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DTC P1300: RANDOM MISFIRE DETECTED, POTENTIAL CATALYST DAMAGE Saab 9-5 I

Testing & Diagnostics ~891 words
  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»(ref-2997-S21108806982000041700000) 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)»(ref-3001-S37270964222000041700000) under MODULES, RELAYS & SOLENOIDS in 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 and retest system. (Схема №1)- (Схема №5) for EVAP canister purge valve, ECM and sensor locations. See «ENGINE CONTROL MODULE (ECM)»(ref-2997-S17585372472000041700000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article. If all sensors are within specified range, go to next step. NOTE: Atmosphere Absolute Pressure sensor is inside ECM and cannot be replaced separately.
  6. Disconnect EVAP canister purge valve electrical connector. Connect SST 86 11 857 test light (Схема №9) or equivalent between purge valve harness connector terminals No. 1 and 2 to prevent code from setting during testing. Turn off A/C, start engine and allow to idle. Use scan tool to check AIRMASS DEVIATION FROM CALCULATED. If deviation is between -15 percent and -25 percent, go to next step. If deviation is not as specified, go to step 8.
  7. Check for plugged EVAP canister purge valve circuit or crankcase ventilation system, vacuum leaks at power brake booster or vacuum hoses. Pinch off vacuum hoses and watch scan tool display. There should be no noticeable change in airmass deviation, except that small crankcase ventilation hose should cause about a 5 percent change when pinched off. If no problems are found, replace MAF sensor. If a problem is found, repair as necessary. Go to step 10.
  8. Reconnect EVAP canister purge valve electrical connector. 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.
  9. Inspect fuel system. See FUEL PRESSURE, FUEL PUMP FLOW and FUEL INJECTORS under «FUEL SYSTEM»(ref-2995-S13928686752000041700000) in BASIC DIAGNOSTIC PROCEDURES article. If any fuel system problems are found, repair as necessary. Go to next step.
  10. Use scan tool to select ACTIVATE: RESET MISFIRE AND KNOCK COUNTERS. Test drive vehicle and monitor current readings for MISFIRE CYL 1-6. 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.
  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 pertinent DTCs, go to next step.
  12. Replace catalytic converter and use scan tool to clear all system DTCs. On V6 engines, drive vehicle for 5 minutes under varying loads and engine RPM, then recheck for any stored DTCs. If pertinent DTC is present, substitute known good ECM and retest system. See «ENGINE CONTROL MODULE (ECM)»(ref-2997-S17585372472000041700000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article.

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