Subaru 2009 IMPREZA Service Manual page 1669

Diagnostic Trouble Code (DTC) Detecting Criteria
AS: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 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 mis-
fire
The following detecting methods are adopted for these detection.
1) Intermittent misfire: FTP 1.5 times misfire
• 180° Interval Difference Method (MT: 1,800 rpm or less, AT: None)
• 360° Interval Difference Method (whole range)
• 720° Interval Difference Method (3,000 rpm or more)
2) Misfire every time: FTP 1.5 times misfire, Catalyst damage misfire
• 360° Interval Difference Method
2. ENABLE CONDITIONS
Secondary Parameters
All secondary parameters enable condi-
tions
Intake manifold pressure change at
180°CA
Throttle position change during 16 milli-
seconds
Fuel shut-off function
Fuel level
Vehicle dynamic control or AT torque
control
Evaporative system leak check
Engine speed
Intake manifold pressure
Battery voltage
Fuel parameter determination
Elapsed time after starting the engine
Engine load change during 32 millisec-
onds
Enable Conditions
1024 ms
< Value of Map 1
< 14 °
Not in operation
9.6 2 (2.54 US gal,
2.11 Imp gal)
Not in operation
Not in operation
500 rpm — 6650 rpm
Value from Map 2
8 V
Not extremely low
volatility
0 ms
< 1000 rpm
GD(H4DOTC)-81
GENERAL DESCRIPTION