Code p 304, I have done spark plugs,wires,ignition coil, top motor mount. Car has been fine for a week then the engine light came on again with same code. Car runs fine, rpm are good.
Cylinder # 4 is misfiring...
I know that I can't figure out what else to do. Replaced all the usual stuff. Car seems to run fine Could be a false light
The causes are: Bad spark plug, bad wire, bad ignition coil for that cylinder, dirty or bad injector, or bad compression.
Remove the spark plug from that cylinder and look at the tip. Sounds like the plug is fouling out. If it's wet and smells of gasoline it's probably a leaky fuel injector. If it's black and oily I'd suspect a weak valve guide seal or weak rings on that cylinder. Especially if this is an older model with some miles on it. Run a compression test on that cylinder. If it's lower than it should be (usually around 150 PSI is good) get a spark plug anti fouler. This is really a "Band-Aid" but will cure the problem for awhile. HTH. -Jim
Plug was dry, not wet or black and oily. Car seems to run fine. Has a little knock when cold and shakes a little when at a stop
What's the compression reading on the cylinder? What kind of car is this? -Jim
Compression or anything to do with the spark is all I can come up with.
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