what causes misfire on no. 1 sparkplug

Question

put on new valve cover gasket and changed spark plugs. now misfire on number one spark plug

Answer 1

Hi there

There can be a few different things that would cause this code. Since you replaced the spark plug that is eliminated, but there is still the coil or plug wire that can cause it. Also, a bad fuel injector or an intake manifold gasket leak will cause it as well. Since it happened after doing the valve cover, I would suspect a bad connection on the coil, or the coil itself.