P0301

DTC P0301 CYLINDER 1 MISFIRE DETECTED

1. 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 three patterns below. Intermittent misfire (Different cylinders misfire intermittently.):

- 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
The following detecting methods are adopted for these detection.

1. Intermittent misfire: FTP 1.5 times misfire
- 120 degrees Interval Difference Method
- 360 degrees Interval Difference Method (whole range)
- 720 degrees Interval Difference Method (3,000 rpm or less)

2. Misfire every time: FTP 1.5 times misfire, Catalyst damage misfire
- 360 degrees Interval Difference Method




2. ENABLE CONDITIONS

3. GENERAL DRIVING CYCLE
- If conditions are met, detect misfire from idling to high rotation.
- Perform the diagnosis continuously.

4. DIAGNOSTIC METHOD




When a misfire occurs, the engine RPM will decreased and the crankshaft position speed will change. Calculate the interval difference value (diagnostic value) from crankshaft position speed by the given formula, and judge whether a misfire is occurring or not comparing the calculated result with judgment value. Counting the number of misfires, if the misfire ratio is higher during 1000 rev. or 200 rev. Judge corresponding cylinders as NG.




As shown in the figure, pick a cylinder as the standard and name it omg 0. And the former crankshaft position speed is named omg 1, the second former crankshaft position speed is named omg 2, the third is named omg 3, etc.




120 degrees Interval Difference Method




360 degrees Interval Difference Method




720 degrees Interval Difference Method




- FTP 1.5 times misfire (Misfire occurrence level which influences exhaust gas)




- Catalyst damage misfire (Misfire occurrence level damaging catalyst)

5. DTC CLEAR CONDITION
- When the OK idling cycle is completed 40 times in a row
- When "Clear Memory" is performed

6. MALFUNCTION INDICATOR LIGHT CLEAR CONDITIONS
- When the OK driving cycle is completed 3 times in a row
- When "Clear Memory" is performed

7. FAIL SAFE
None

8. ECM OPERATION AT DTC SETTING
Memorize the freeze frame data. (For test mode $02)