MFI System Inspection

INSPECTING THE MFI SYSTEM

If the MFI system components (sensors, PCM, injector, etc.) fail, the interruption or failure to supply the proper amount of fuel for various engine operating conditions will result. The following situations may be encountered:

1. Engine is hard to start or does not start at all
2. Unstable idle
3. Poor driveability

If any of the above conditions is noted, first check for trouble codes and make basic engine checks (ignition system malfunction, incorrect engine adjustment, etc.). Then, inspect the MFI system components.

ON-BOARD DIAGNOSTICS
- Diagnostic trouble codes are set as follows:
After the PCM first detects a malfunction, a diagnostic trouble code is recorded when the engine is restarted and the same malfunction is re-detected. (The malfunction is detected in driving cycle). However, for fuel system rich/lean misfiring, a diagnostic trouble code is recorded on the first detection of the malfunction.
- Erasing diagnostic trouble codes:
After recording the diagnostic trouble code, if the PCM does not re-detect the malfunction for 40 driving cycles, the diagnostic trouble code will be erased from the PCM memory. However, for fuel system rich/lean or misfiring, the diagnostic trouble code will be erased if both of the following conditions are met:
- When driving conditions (engine speed, engine coolant temperature, etc.) are identical to those when the malfunction was first recorded.
- When the PCM does not re-detect the malfunction for 80 driving cycles.

NOTE: A "driving cycle" is completed as soon as the vehicle goes into closed-loop operation.