Outline Of Diagnosis

Detect the presence of misfire occurrence. (Revolution fluctuation method)

Monitoring Misfire which influences exhaust deterioration (1.5 times of FTP) and catalyst damage is made obligatory by the law. Misfire affecting these two has two patterns below:

• Intermittent misfire (The same cylinder misfires in random, or different cylinders misfire in random.): FTP 1.5 times misfire
• Every time misfire (The same cylinder misfires every time.): FTP 1.5 times misfire, Catalyst damage misfire
• Misfire on opposite cylinders (Misfire occurs at opposed cylinder): FTP 1.5 times misfire, Catalyst damage misfire

The following detecting methods are adopted for these detection.

1. Intermittent misfire: FTP 1.5 times misfire
   • 120° Interval Difference Method
   • 360° Interval Difference Method
   • 720° Interval Difference Method
2. Misfire every time: FTP 1.5 times misfire, Catalyst damage misfire
   • 120° Interval Difference Method
   • 360° Interval Difference Method
3. Misfire on opposite cylinders: FTP 1.5 times misfire, Catalyst damage misfire

• 120° Interval Difference Method