General Precautions of EFI System Maintenance
F-99
III. Diagnostic Flow for Inspection and Maintenance by M7 System
according to Malfunction Symptoms
Before enabling the malfunction diagnostic steps as per engine malfunction symptoms, please firstly perform
the primary inspections below
1. Confirm that the engine malfunction indicator lamps are working normally
2. Use malfunction diagnostic instrument for inspection and confirm no malfunction information record is
available
3. Confirm that the malfunction symptom in the owner’s complaint exists, and confirm trouble causes.
Then proceed to appearance inspection:
(1) Check fuel pipeline for any leakage;
(2) Check vacuum pipe for rupture or twist, and for correct connection;
(3) Check intake pipeline for blockage, leakage, pressed, or damaged;
(4) Check high voltage wire of ignition system for rapture or ageing, and for correct ignition sequence;
(5) Check whether or not the wire harness grounding is clean and firm;
(6) Check whether or not the joints of respective sensors and actuators are loosened or under bad contact
condition
Important Notes: If the abovementioned symptoms exist, the maintenance operation is then to be performed
firstly aiming at the corresponding malfunction symptoms, otherwise, the malfunction diagnosis and
maintenance afterwards will be affected.
Diagnostic Help:
1. Confirm no engine malfunction record is available at all
2. Confirm the complained malfunction symptom exists
3. It has been inspected according to the abovementioned steps, and no anomaly has been found
4. Don’t ignore vehicle maintenance status, cylinder pressure, mechanical ignition timing, fuel status, and
other factors that impacts on the system in the process of inspection and maintenance
5. Replace ECU and perform test.
At this point if the malfunction symptom can be removed, then the malfunction is located at ECU, and if
the malfunction symptom still exists, then the original ECU shall be changed back, to carry out the work
on inspection and maintenance, in the repeated flow.
1. No rotation or slow rotation of engine when started.
2. Engine rotates but without being started.
3. Difficult warming-up start of engine.
4. Difficult cold start of engine.
5. Difficult start of engine at any time with normal rotation speed.
6. Normal start with unstable idling speed at any time.
7. Normal start with unstable idling speed during warming up
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