The 2022 GMC Sierra offers premium full-size truck capability with powerful V8 engines featuring Dynamic Fuel Management for enhanced efficiency. When your Sierra displays P0304 indicating a cylinder 4 misfire, systematic diagnosis identifies whether the cause is ignition, fuel, or DFM-system related.
Understanding P0304 in Your Sierra
The Sierra's 5.3L and 6.2L V8 engines use Dynamic Fuel Management to improve fuel economy by deactivating cylinders under light load. Cylinder 4 is located on the right (passenger) bank of the V8. The engine control module monitors combustion quality through crankshaft position analysis.
DFM System Factors
The DFM system in your Sierra uses hydraulic lifters that can activate and deactivate individual cylinders. When these lifters develop issues, misfires can occur—particularly during the cylinder deactivation transitions common during highway cruising. The system requires proper oil level and quality to function correctly.
Diagnostic Process
Access the cylinder 4 ignition coil on the right bank. Inspect spark plug and ignition coil condition. Pay attention to when misfires occur—during steady cruise suggests DFM involvement. Check oil level and condition. Verify no vacuum leaks exist in the intake system.
Repair Recommendations
Replace spark plugs with AC Delco specifications. Test ignition coil output. If DFM lifter issues are suspected, inspection requires valve cover removal. Some owners opt for DFM/AFM disable devices to eliminate the cylinder deactivation system, though this affects fuel economy.