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MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS TSB Revision MULTIPORT FUEL INJECTION (MFI) <2.4L ENGINE> 13A-405 • Engine coolant temperature is higher than 77°C (171 °F). • Mass airflow sensor output is 6 g/sec or less. Judgment 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 +15.0 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 77°C (171 °F). • Mass airflow sensor output is 6 g/sec or more. Judgment 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 +20.0 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 77°C (171 °F). • Mass airflow sensor output is 6 g/sec or less. Judgment 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 +25.0 percent for 5 seconds. Check Conditions • Engine coolant temperature is higher than 77°C (171 °F). • Under the closed loop air/fuel ratio control. Judgment Criteria • Long-term fuel trim has continued to be +12.5 percent for 5 seconds. or • Short-term fuel trim has continued to be +25.0 percent for 5 seconds. . OBD-II DRIVE CYCLE PATTERN − 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 1, 4) failed. • Incorrect fuel pressure. • Air drawn in from gaps in gasket, seals, etc. • Engine coolant temperature sensor failed. • Intake air temperature sensor failed. • Barometric pressure sensor failed. • Manifold absolute pressure sensor failed. • Exhaust leak. • Use of incorrect or contaminated fuel. • Harness damage in cylinder 1, 4 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. Check for exhaust leak. YES : Repair it. Then go to Step 15. |