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MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS TSB Revision MULTIPORT FUEL INJECTION (MFI) 13A-389 Check Conditions • Engine coolant temperature is lower than approx- imately 100 °C (212°F) when the engine is started. • Intake air temperature is lower 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). • Volume airflow sensor output frequency is 100 Hz 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 +12.5 percent for 5 seconds. Check Conditions • Engine coolant temperature is higher than approximately 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). • Volume airflow sensor output frequency is 100 Hz or more. 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 +17.6 percent for 5 seconds. Check Conditions • Engine coolant temperature is higher than approximately 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). • Volume airflow sensor output frequency is 100 Hz 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 +22.3 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 per- cent 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:) • Volume 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. • Exhaust leak. • Use of incorrect or contaminated fuel. • Harness damage in injector. • Connector damage. • Intake system vacuum leaks. • PCM failed. |