We've been chasing a problem on a rough running 2001 Silverado. The truck generates a code p0300 random multiple misfires detected. We changed all the plugs and wires and there is no difference. The plugs were all fine with the exception of one cylinder. That plug was black. The coil pack on that cylinder is producing spark, but I am not sure how strong it is. We just let it spark against the exhaust manifold. What else could it be? Should we replace that coil pack on the cylinder even though it produced spark? I had also thought it might be a bad injector, but would that cause the computer to generate a misfire code?
I just pulled the new plug on the questionable cylinder and it is already black. The computer still reports multiple random misfires.
I just pulled the new plug on the questionable cylinder and it is already black. The computer still reports multiple random misfires.