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MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS TSB Revision MULTIPORT FUEL INJECTION (MFI) <3.0L ENGINE> 13B-305 Judgement Criteria • Long-term fuel trim has continued to be higher than +12.5 percent for 5 seconds. or • Short-term fuel trim has continued to be higher than +12.5 percent for 5 seconds. Check Conditions • Engine coolant temperature is higher than 100°C (212 °F) when the engine is started. • Intake air temperature is higher than 60°C (140 °F) when the engine is started. • Under the closed loop air/fuel ratio control. • Engine coolant temperature is higher than 76°C (169 °F). • Mass airflow sensor output is 12 g/sec or more. Judgement Criteria • Long-term fuel trim has continued to be higher than +12.5 percent or 5 seconds. or • Short-term fuel trim has continued to be higher than +17.6 percent for 5 seconds. Check Conditions • Engine coolant temperature is higher than 100°C (212 °F) when the engine is started. • Intake air temperature is higher than 60°C (140 °F) when the engine is started. • Under the closed loop air/fuel ratio control. • Engine coolant temperature is higher than 76°C (169 °F). • Mass airflow sensor output is 12 g/sec or less. Judgement Criteria • Long-term fuel trim has continued to be higher than +12.5 percent or 5 seconds. or • Short-term fuel trim has continued to be higher than +22.3 percent for 5 seconds. Check Conditions • Engine coolant temperature is higher than 76°C (169 °F). • Under the closed loop air/fuel ratio control. Judgement Criteria • Long-term fuel trim has continued to be +12.5 percent for 2 seconds. or • Short-term fuel trim has continued to be +25.0 percent for 2 seconds. . OBD-II DRIVE CYCLE PATTERN Refer to Diagnostic Function − OBD-II Drive Cycle − Pattern 20 . TROUBLESHOOTING HINTS (The most • Mass airflow sensor failed. • Injector (Number 1, 3, 5) failed. • Incorrect fuel pressure. • Air drawn in from gaps in gasket, seals, etc. • Intake air temperature sensor failed. • Manifold absolute pressure sensor failed. • Exhaust leak. • Use of incorrect or contaminated fuel. • Harness damage. • Connector damage. • ECM failed. DIAGNOSIS Required Special Tools: • MB991958: Scan Tool (M.U.T.-III Sub Assembly) • MB991824: V.C.I. • MB991827: USB Cable • MB991910: Main Harness A |