What causes 4 cylinder misfire problem and how can i fix it?

Question

Thanks folks for reply, but I did change the plugs, the wires, the coil, fuel filter, air filter, oil and oil filter, switched injectors.Nothing helps, although after adding a better grade fuel check engine light switched off. My next step to change valve cover gasket. Any more thoughts? thanks.

Answer 1

You don't say what the ignition system is, you have to be aware of that before you can diagnose the problem, but it is in there somewhere.

Answer 2

several things can cause it, but for starters lets go with the main stuff. change the plugs, plug wires, distributor cap and rotor. also a vacuum leak can cause rough idle. check those things out first before getting into the valve train.

Answer 3

could be a number of reasons bad plug or plug wire coil