The 2022 Chevrolet Tahoe offers three engine options: 5.3L V8, 6.2L V8, and 3.0L Duramax diesel. When P0300 random misfire appears with rough idle, the diagnostic approach varies by powertrain. All share certain fundamentals, but each engine has unique considerations.
Understanding P0300 Across Engine Types
P0300 indicates the engine computer detected misfires occurring randomly across multiple cylinders rather than isolated to one. This typically points to system-wide issues like fuel quality, ignition problems affecting all cylinders, or vacuum leaks. The diesel Duramax handles misfires differently than gasoline V8s due to compression ignition.
5.3L and 6.2L V8 Considerations
Both gasoline V8s in the 2022 Tahoe use Active Fuel Management (Dynamic Fuel Management on 6.2L) to deactivate cylinders for fuel economy. These systems can contribute to rough idle if the deactivation mechanisms malfunction. Lifter issues have affected some GM V8s, causing both misfire symptoms and the characteristic "tick."
Spark plug and ignition coil issues cause misfires in the gasoline engines. GM's recommended spark plug service interval is 97,500 miles, but plugs can fail earlier. A weak or failing coil may cause misfires under load that become random across cylinders as multiple coils age.
3.0L Duramax Diesel Specifics
The Duramax doesn't use spark plugs—it ignites fuel through compression. Random "misfires" in the diesel relate to fuel injection timing, injector performance, or compression issues. The high-pressure fuel system must maintain precise delivery to each cylinder.
Glow plug issues in the diesel can cause rough cold starts that improve once warm. While not technically misfires, the symptoms feel similar to drivers and may trigger rough-running codes.
Common Causes Across All Engines
Fuel quality affects all engines. Contaminated fuel or water in fuel causes combustion problems regardless of engine type. If misfires started shortly after fueling, suspect fuel quality.
Vacuum leaks in the gasoline engines introduce unmeasured air, leaning the mixture. Check intake manifold gaskets and any vacuum-operated accessories for leaks.
Diagnostic Approach
For gasoline engines, start with spark plugs and coils, then check for vacuum leaks. For the diesel, focus on fuel system integrity and injector performance. Freeze frame data showing when codes set provides clues—misfires only at idle suggest different causes than misfires under load.