MFI system inspection

If MFI system components (sensors, ECM, injectors, etc.) malfunction, fuel delivery to the engine cylinders is disrupted under various operating conditions, resulting in the following symptoms:

– engine is hard to start or will not start;
– engine idles roughly;
– engine runs roughly under all conditions.

If any of the above symptoms occur, first perform standard diagnostics (ignition system, engine adjustments, etc.), then inspect the MFI system components using the HI-SCAN special scan tool.

Before removing or replacing any system component, read the diagnostic trouble codes, then disconnect the cable from the negative battery terminal.

Before disconnecting the cable from the negative battery terminal, turn the ignition switch OFF. Disconnecting the cable with the engine running or the ignition ON may damage the ECM.

The oxygen sensor is connected to the ECM with a shielded wire to reduce possible radio interference from the ignition system. If the shielding braid is damaged, replace the wire.

When inspecting the generator, do not disconnect the cable from the positive battery terminal to prevent damage to the ECM.

When charging the battery installed in the vehicle from an external power source, disconnect the vehicle electrical system wires from the battery terminals beforehand to prevent damage to the ECM.