2000 Blazer P0300 Misfire Code: Diagnosis and Next Steps After Multiple Repairs
I own a 2000 Chevrolet Blazer that has been showing a persistent P0300 misfire code. A mechanic initially suggested replacing the fuel injectors, which I did—no improvement. Later, I discovered that the distributor cap and rotor were damaged, so I replaced both with new components. Additionally, I installed a new coil, spark plug wires, and an EGR valve. Despite these repairs, the P0300 code has returned. I've been researching online for solutions, but haven't found a clear resolution. At this point, I'm considering replacing the oxygen (O2) sensors as the next step. Can anyone confirm if O2 sensor replacement is a viable solution for this issue? Any additional diagnostics or suggestions would be greatly appreciated.
You've replaced many components, but it's important to use your OBD2 scanner to check key sensors and parameters: ECT (Engine Coolant Temperature), MAP (Manifold Absolute Pressure), MAF (Mass Air Flow), TPS (Throttle Position Sensor), fuel trims, and O2 sensor voltage readings. Also, confirm the fuel pressure—what is it in PSI? Make sure you're using AC Delco spark plugs for optimal performance.