P0304=misfire in cylinder 4. coil? spark plug? spark plug wiring. 1999 crown vic 4.6 V8. runs ok, just little cutting out every now and then.

Misfire could be coil issue or poor compression depending at what point it misfires.
EVAP issue could be a leaking fuel filler cap or an air leak in the vacuum pipes.

check that your spark plug wires are all secured tight. the far right cylinder is giving you the issue, cylinder #4. Is the engine light flashing while the car is running? if it isnt flashing, then its a past code and isnt misfiring anymore. if the engine light is flashing, you either have a bad plug wire, or a bad ignition coil/distributor.

P0304 Code - Cylinder #4 Misfire Detected
A P0304 code means that the the car's computer has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #4.

Symptoms may include:
* the engine may be harder to start
* the engine may stumble / stumble, and/or hesitate
* other symptoms may also be present

Causes: A code P0304 may mean that one or more of the following has happened:
* Faulty spark plug or wire
* Faulty coil (pack)
* Faulty oxygen sensor(s)
* Faulty fuel injector
* Burned exhaust valve
* Faulty catalytic converter(s)
* Running out of fuel
* Poor compression
* Defective computer

Possible Solutions:
If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.


Hope helps.

P0304 is a #4 cylinder misfire. Swap the plug, coil and wire with a different cylinder to see if the code changes to that cylinder or stays with cylinder #4. If the code stays, the fuel injector will need to be replaced. If the code follows the components you changed then your problem is in the components and you can do further swaping of each indiviual component to determine the bad part.

P0304 means that cylinder 4 has a misfire and P0305 is a cylinder 5 misfire. What this means is you may have bad spark plugs, or bad plug wires, or you may need to replace your distributor cap and rotor. I would start with plugs and wires.

the code that is given means that the coil, plug ,plug wires, for that cylinder could be bad, check spark plug and see if this is the problem or a bad wire.

i have a 2001 chevy z-71 5.3L. I keep getting a random/multiple misfire code for cylinder 1 . I have replaced plugs, wires, coil pack(only on #1 cylinder)., and fuel pump. I still keep getting the cylinder 1 misfire code. I put truck on a scanner and watched the cylinders. # 1 misfires at idle but quickly stops misfiring at around 1000 rpms. you can here the engine miss at idle but truck runs great on road . anyone else ever had this problem?

first cylinder 4 is the last on the passenger side . first pull the coil out and check if there is water where the plug is. if there is take the water out and dry up the coil. if you find water you got a crack manifold or a bad intake manifold gasket. if there is no water replace the coil. good luck

u have 2 bad coils

IS THIS A 99 CROWN VIC? IF SO IS IT MISFIRING? IF THIS IS THE CASE YOU MORE THAN LICKLY NEED PLUG WIRES.

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