Cylinder 4 misfire

Hello everyone, I have my check engine light on. It come on and goes off but, mostly stays on and the engine vibrates. I had the code reader checked and it says P0304 misfire cylinder 4. I have replace all spark plugs and replaced the coil on cylinder 4. Engine runs smooth again, actually sounds better. But, check engine light is still on with the same code reading. Question, do I run the truck for awhile and let the truck code reset itself? Thanks for your time, Ted

 

You have to use your code reader to clear the codes from your truck. It will not reset itself.

 

Thanks for the reply. It works great and light is off.

 

OK, my light came back on. Engine is still running great with no vibration in motor. Should I replace the coil connector wiring?

 

Wiring is part of harness so you may have a problem replacing that.
However since your truck is 05, and that year had problems with headgasket I would do a tests for bad headgasket.

 

Misfiring does not mean ignition misfiring. It means there is no power from that cylinder. It can range from ignition problems, (coil, plug,etc) to fuel issue (fuel pump, dirty injector, fuel injector clogged, injector control issue) or air issues (valves, clogged air filter, worn cam)

You need to get it properly diagnosed before you put money in it that you don't need to. Just a suggestion.

 

I went through the same thing with my wife's 4Runner. Cylinder 4 code. Changed plugs still had code, then changed coils and wires still had code, and finally changed the fuel injector which was a straightforward repair. New injector solved the problem. I found an OEM one on Amazon for about $56. 2000 4Runner with 163K miles, and stills runs great.