P0300 Buick Lesabre

Question

Code came up p0301, changed plugs & wires, checked ignition coil. Drove it and still felt like it wanted to stall out. Code came up p0300 engine turns over but won't start. Could catalytic converter be plugged? What else should I look for?

Answer 1

P0300 Random misfire 

Catalytic convertor can be plugged from a prolong misfire , If the catalytic was plugged you would experience lack of power and a hissing noise coming from the airfilter housing as you accelerate Now that vehicle does not start you would need to  check for fuel pressure

 These igntion coil are waste spark. Means it fire for 2 cylinders. When number 1 fire so does cylinder 4, You can swap the coil with a known working coil or use a known good working igntion coil. and retest for the misfire

 Another area to test for the vehicle running like it wants to stall out is the fuel pressure regulator. with the engine  running, Pull the vacuum hose line from the fuel pressure regulator, if fuel seep out from its vacuum port, you would need a fuel pressure regulator