Flow of Diagnosis

When checking engine troubles, it is important to start with an inspection of the basic systems. If one of the following conditions exists, (A) engine start failure, (B) unstable idling or (C) poor acceleration, begin by checking the following basic systems.
1. Power supply
- Battery
- Fusible link
- Fuse
2. Body ground
3. Fuel supply
- Fuel line
- Fuel filter
- Fuel pump
4. Ignition system
- Spark plug
- High-tension cable
- Ignition coil
5. Emission control system
- PCV system
- Vacuum leak
6. Others
- Ignition timing
- Idle speed
Troubles with the Multiport Fuel Injection (MFI) system are often caused by poor contact of the harness connectors. It is important to check all harness connectors and verify that they.





MFI SYSTEM INSPECTION
If the Multiport Fuel Injection (MFI) system components (sensors. Engine Control Module (ECM), injector, etc.) fail, interruption or failure to supply the proper amount of fuel for various engine operating conditions will result. The following situations can 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 perform an inspection by self diagnosis and subsequent basic engine checks (ignition system malfunction, incorrect engine adjustment, etc.), and then inspect the MFI system components with the Scan Tool (ST).

NOTES: Before removing or installing any part, read the diagnostic trouble codes and then disconnect the battery negative (-) terminal. Before disconnecting the cable from battery terminal, turn the ignition switch to OFF. Removal or connection of battery cable during engine operation or while the ignition switch is ON could cause damage to the ECM. The control harnesses between the ECM and heated oxygen sensor are shielded wires with the shield grounded to the body in order to prevent the influence of ignition noises and radio interference. When the shielded wire is faulty the control harness must be replaced.