P0303
DTC P0303 - CYLINDER 3 MISFIRE DETECTEDOUTLINE OF DIAGNOSIS
Detect the presence of misfire occurrence.
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.): FTP 1.5 times misfire
- Every time misfire (The same cylinder misfires every time.): Catalyst damage misfire, FTP 1.5 times misfire
- Opposed misfire (Dual ignition equipped model as #1, #2 simultaneously ignite. NA model only.): Catalyst damage misfire, FTP 1.5 times misfire
The following detecting methods are adopted for these detection.
1. Intermittent misfire: FTP 1.5 times misfire
- 180 ° Interval Difference Method (3,550 rpm or less)
- 720 ° Interval Difference Method (2,950 rpm or less)
2. Every time misfire: Catalyst damage misfire, FTP 1.5 times misfire
- 180 ° Interval Difference Method (3,550 rpm or less)
- Pattern Recognition Method (2,950 rpm or more)
3. Opposed misfire: Catalyst damage misfire, FTP 1.5 times misfire
- 180 ° Interval Difference Method (3,550 rpm or less)
- Pattern Recognition Method (2,950 rpm or more)
ENABLE CONDITION
GENERAL DRIVING CYCLE
If the condition matched, detecting misfire is possible in the engine speed of idling to high revolution.
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, and judge whether the misfire occurs or not comparing the calculated result with judgment value.
For misfire detection, there are three methods such as 180 ° Interval Difference Method, 720 ° Interval Difference Method and Pattern Recognition Method.
- 180 ° Interval Difference Method, 720 ° Interval Difference Method
Transform the time needed for crankshaft movement from BTDC 65 ° to BTDC 10 ° into revolution. As the following, regard the revolution as MNXO. And then regard the former revolution as MNX1, the second former revolution as MNX2, and the third as MNX3, etc.
Use the detecting method below for misfire patterns, and judge misfire occurrence when the result calculated from the formula is out of threshold value.
- Pattern Recognition Method
Pattern Recognition Method has two patterns such as every time misfire on one cylinder and continuous misfire on two cylinders.
Every time misfire on one cylinder
Calculate the simple average (calculate MNXO-MNX 1) per one hundred ignitions for one cylinder (per four hundred ignitions for four cylinder).
Regard the value calculated for #1 cylinder as AVE1, #2 cylinder as AVE2, and as AVE3, AVE4 like the same way. Judge misfire occurrence when the value calculated from the following formula is larger than threshold value.
(Max. value of AVE1 to AVE4) - AVEn (n=1,2,3,4) >= threshold value -> Judge that misfire occurs.
Continuous misfire on two cylinders
1. Two continuous ignitions with "MNX 0 - MNX 1 >= threshold value" occurs.
2. Two continuous ignitions with "MNX 0 - MNX 1 <= - (threshold value)" occurs.
Judge misfire occurrence on continuous two cylinders when the judgment criteria (1) and (2) above repeated for four hundred ignition.
- FTP 1.5 times Misfire (Misfire occurrence level which influences exhaust gas)
- Catalyst Damage Misfire (Misfire occurrence level which results in catalyst damage)
DTC CLEAR CONDITION
- When the OK idling cycle is completed 40 times in a row
- When "Clear Memory" was performed
MALFUNCTION INDICATOR LIGHT CLEAR CONDITION
- When diagnosed OK with the similar driving for 3 driving cycles in a row
- When "Clear Memory" was performed
FAIL SAFE
None
ECM OPERATION AT DTC SETTING
Memorize the freeze frame data. (For test mode $02)