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MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS TSB Revision MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE> 13B-444 Judgment Criteria • Long-term fuel trim has continued to be lower than −12.5 percent for 5 seconds. or • Short-term fuel trim has continued to be lower than −12.5 percent for 5 seconds. Check Conditions • Engine coolant temperature is higher than 76°C (169 °F). • Under the closed loop air/fuel ratio control. Judgment Criteria • Long-term fuel trim has continued to be −12.5 percent for 2 seconds. or • Short-term fuel trim has continued to be −30.0 percent for 2 seconds. . OBD-II DRIVE CYCLE PATTERN Refer to Diagnostic Function − OBD-II Drive Cycle − Procedure 2 − Fuel Trim Monitor . TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:) • Mass airflow sensor failed. • Injector (Number 2, 4, 6) failed. • Incorrect fuel pressure. • Engine coolant temperature sensor failed. • Intake air temperature sensor failed. • Barometric pressure sensor failed. • Manifold absolute pressure sensor failed. • Harness damage in left bank injector circuit or connector damage. • PCM failed. DIAGNOSIS Required Special Tools: • MB991958: Scan Tool (MUT-III Sub Assembly) • MB991824: V.C.I. • MB991827: USB Cable • MB991910: Main Harness A STEP 1. Using scan tool MB991958, check data list item 12: CAUTION To prevent damage to scan tool MB991958, always turn the 12, Mass Airflow Sensor. (4) Warm up the engine to normal operating temperature: 80 °C to 95 °C (176°F to 203°F). • When idling, between 2.0 and 6.0 g/sec. • When 2,500 r/min, between 8.0 and 16.0 g/sec. (5) Turn the ignition switch to the "LOCK" (OFF) position. YES : YES: Go to Step 2. − Mass Airflow Circuit Range/Performance Problem , DTC P0102 − Mass Airflow Circuit Low Input , DTC P0103 − Mass Airflow Circuit High Input AC305412 AB MB991910 DATA LINK CONNECTOR MB991824 MB991827 |