P0304-MISFIRE DETECTED CYLINDER #4
For a complete wiring diagram Refer to Section 8W
- When Monitored:
With the engine running.
- Set Condition:
The ECM detects multiple misfires from cylinder #4.
| Possible Causes |
| ENGINE COMPRESSION |
| FUEL INJECTOR QUANTITY |
| FUEL SUPPLY CONTAMINATION |
| INJECTOR LEAKAGE |
| INTERMITTENT CONDITION |
Diagnostic Test
1. CHECK FOR ACTIVE DTCNOTE: If the ECM detects and stores a DTC, the ECM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the scan tool at the same time the DTC is displayed.
NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for an active DTC.
With the scan tool, erase ECM DTCs.
Test drive the vehicle and attempt to duplicate the problem.
With the scan tool, read ECM DTC's.
Did this DTC set again?
Yes
- Go To2
No
- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
2. FUEL CONTAMINATION
Refer to the Service Information and inspect the fuel supply for contamination.
Is the fuel contaminated?
Yes
- Refer to the Service Information to remove and replace fuel throughout the fuel system.
- Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).
No
- Go To3
3. ENGINE COMPRESSION
Turn the ignition off.
With the scan tool, perform the Cylinder Compression Test.
Is the cylinder compression within specification for all cylinders?
Yes
- Go To4
No
- Repair as necessary in accordance with the Service Information.
- Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).
4. FUEL INJECTOR QUANTITY
Turn the ignition off.
With the scan tool, perform the Injector Quantity Test.
Is the Injector Quantity within specification for all cylinders?
Yes
- Go To5
No
- Repair or replace as necessary in accordance with the Service Information.
- Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).
5. FUEL INJECTOR LEAKAGE
Turn the ignition off.
Perform the INJECTOR LEAKAGE TEST in accordance with the Service Information.
Were any problems found?
Yes
- Repair or replace as necessary in accordance with the Service Information.
- Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).
No
- Test Complete.