P0301

DTC P0301 CYLINDER 1 MISFIRE DETECTED

1. OUTLINE OF DIAGNOSIS
Detect whether the misfire occurred or not. (Revolution fluctuation method) Monitoring the 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 (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
- 180 degrees Interval Difference Method (MT: 1,800 rpm or less; AT: None)
- 360 degrees Interval Difference Method (whole range)
- 720 degrees Interval Difference Method (3,000 rpm or less)
2. Every time misfire: FTP 1.5 times misfire, Catalyst damage misfire
- 360 degrees Interval Difference Method







2. ENABLE CONDITION

3. GENERAL DRIVING CYCLE
^ Detecting misfire is able to be carried out in the condition between idling and high revolution.
^ Perform the diagnosis continuously.

4. DIAGNOSTIC METHOD







When the misfire occurred, the engine speed is decreased and the crankshaft position speed will change. Calculate the interval difference value (diagnostic value) from crankshaft position speed by the following formula, and judge whether the misfire occurs or not comparing the calculated result with judgment value. Counting the number of misfire up, and if the misfire ratio is higher during 1,000 rev. or 200 rev., judge NG for the corresponding cylinder.




As the figure, pick out a random 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,and the following is the same.




^ 180 degrees Interval Difference Method




^ 360 degrees Interval Difference Method




^ 720 degrees Interval Difference Method




^ FTP 1.5 times misfire (Misfire occurrence level affecting exhaust gas)
Judgment Value (Judge that malfunction occurs when the misfire ratio is high in 1,000 engine revs.)




^ Catalyst damage misfire (Misfire occurrence level damaging catalyst)

These figures mean the misfire ratio %) in 400 ignitions; for example, 22.5 %) means 400 (ignition) 22.5 %) = 90 (ignition) or more, so this case is judged misfire.

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

6. MALFUNCTION INDICATOR LIGHT CLEAR CONDITION
^ When the OK driving cycle was completed 3 times in a row
^ When "Clear Memory" was performed

7. FAIL SAFE
None

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