Mazda MX-6 1998, Workshop Manual

Page: 75 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
DTC P0300
P0301
P0302
P0303
P0304
Random misfire detected
Cylinder No.1 misfire detected
Cylinder No.2 misfire detected
Cylinder No.3 misfire detected
Cylinder No.4 misfire detected
DESCRIPTION
• DTC P0300 indicates multiple cylinders misfiring or Camshaft Position (CMP) sensor
failure resulting in cylinder misfire
• DTCs P0301, P0302, P0303 or P0304 indicate specific cylinder misfiring
[Possible Cause]
• Ignition system • Purge solenoid valve
• Fuel injection • Base engine
• Fuel pressure • Running out of fuel
• Evaporative Emission System
Warning
Following troubleshooting flow chart contains fuel system diagnosis and repair procedures. Read following
warnings before performing fuel system service:
• Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames
away from fuel.
• Fuel line spills and leaks are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel
can also irritate skin and eyes. To prevent this, always complete “BEFORE REPAIR PROCEDURE” and “AFTER
REPAIR PROCEDURE” described in this manual.
o- 0 1 -1 4 BEFORE REPAIR PROCEDURE
D- 0 1 -1 4 AFTER REPAIR PROCEDURE
STEP INSPECTION
ACTION
1
CHECK POSSIBLE CAUSES TO MISFIRE
Note
•
Running out of fuel may turn on the MIL
and possibly store Continuous Misfire DTC.
• Has vehicle recently run out of fuel?
Yes OBD II system okay.
RESET PCM to completely clear DTCs.
c r After Repair Procedure
RETURN vehicle to customer.
No Go to next step.
2 CHECK FOR OTHER NON-MISFIRE
CONTINUOUS MEMORY DTCS
Check for other non-misfire Continuous
Memory DTCs which could cause the Misfire
DTC.
Possible causes:
• CMP sensor
• Ignition coil primary circuit
• Knock sensor
• Are other non-misfire Continuous
Memory DTCs present?
Yes
ADDRESS next Continuous DTC.
DISREGARD Misfire DTC at this time.
Go to DTC charts and PROCEED as required.
No Go to next step.
3 CHECK FOR ON-DEMAND SELF-TEST
DTCS
Note
• Check for any Key On Engine Off (KOEO)
DTCs, which could cause the misfire DTC.
• Perform KOEO self-tests.
• Are any DTCs presented?
Yes Go to DTC charts and PROCEED as required.
No CHECK spark plugs and secondary wires.
If okay, go to next step.
4 CHECK FOR OTHER KEY ON ENGINE
RUNNING (KOER) DTCS
Note
• Check for any KOER DTCs which could
cause misfire DTCs.
• Are any KOER DTCs displayed on NGS
tester?
Yes If DTCs P1131 is present:
Go to next step.
All others:
Go to DTC charts and PROCEED as required.
No Go to next step.
0 1 -0 1 A -4 7