2004 Chevy Silverado P0300 Code: Rough Idle After Replacing Plugs, Wires, and Coil Pack
My 2004 Chevrolet Silverado has accumulated 245,000 miles and has been consistently throwing a P0300 random misfire code for several months. I've reset the code multiple times, but it returns each time. The engine cranks normally, though it runs with a noticeable rough idle. I've already replaced the spark plugs, ignition wires, and the coil pack on cylinder one—specifically due to a detected misfire there. The truck is equipped with an aftermarket cold air intake, throttle body spacer, ECU programmer, and is dual-fuel configured. While there are many potential components that could contribute to this issue, I'm looking for a clear starting point to diagnose the root cause. Any insights or recommendations would be greatly appreciated.
Try cleaning the Mass Air Flow (MAF) sensor—it's a common culprit in P0300 cases. Did you use AC Delco spark plugs? Many users report better results with OEM or high-quality brands like AC Delco. Investing in an OBD2 scanner to monitor live data is highly recommended for real-time diagnostics. Also consider performing a fuel pressure test and a leakdown test at KOEO (Key On, Engine Off) conditions. By the way, what does 'dual' refer to? Please clarify if it's dual fuel or dual exhaust or another configuration—this detail is important for accurate diagnosis.