1999 GMC Savannah 5.7L with engine code P0300

Question

recently I changed the low manifold gasket, and new fuel injectors, new spark plugs, new rotor cap ignition coil,, new wires, and still the light on (check engine light) my vehicle is a 1999 GMC Savannah 5.7L, please what could be the problem, thanks for your response.

Answer 1

Hi there,

With all that you have done to this already, I would look at the fuel pressure as a possible cause and do a compression test on the engine itself. If you have high miles either could cause multiple cylinder misfires.