P0300 code what is the fix?

Question

I've changed the plugs again on 1 and 4 because they were so black and I changed the coil pack for 1 and 4 but still have no change in condition. I did notice there was smoke coming off the exhaust pipe in front of the cat. Could the cat be causing the exhaust smoke to back up into the engine causing the misfire?

Answer 1

Hi there

It is possible although you would usually get a misfire on all of the cylinders. It is possible there is a problem with the coil or plug wires. If they are good I would check the mechanical timing. If you pull the O2 sensor out of the manifold BEFORE the converter and the car runs better, that indicates a plugged up converter.