P0300 Misfire Code on 2001 Oldsmobile Bravada: Diagnosis and Repair Attempts
I own a 2001 Oldsmobile Bravada with 85,000 miles and have been experiencing recurring engine performance issues. Initially, the vehicle would suddenly buck while driving on highways, with RPMs increasing by approximately 500 RPM and a noticeable loss of control. A local mechanic initially diagnosed this as a misfire but could not identify the root cause. Later, the issue evolved—under normal conditions, the engine would run at around 2,000 RPM at 60 mph, but began running at up to 3,000 RPM under the same speed. This behavior started occurring after driving for a while and then parking with the engine running. After exiting and restarting, the problem would reappear during extended drives. I took it to the shop again, where they confirmed a P0300 random misfire code. They recommended a full tune-up, which I completed—replacing spark plugs, wires, rotor, cap, and performing an oil change. However, the issue returned within days. The vehicle has now been in the shop for three weeks with multiple components replaced, including the distributor rotor, engine control module (ECM), and ECM sensor. Despite these efforts, no resolution has been found. I have searched online forums extensively but cannot find any documented cases of this specific P0300 issue on the 2001 Bravada. I am seeking advice from experienced owners or mechanics to help identify potential causes such as fuel delivery problems, sensor malfunctions, or internal engine wear related to the 4.3L V6 engine.
The P0300 code on a 2001 Bravada may indicate a fuel injection issue, such as a faulty injector or low fuel pressure. I recommend scheduling a professional fuel injection service and adding a fuel additive to the tank several times to clean the injectors and improve combustion efficiency.