SO my Service engine light goes on with my 2003 5.4 and I have the code read and it's a P0304. Misfire on number four. Take it to the dealer and they say I need a complete plug and coil redo along with fuel filter and injector cleaning. Costs me $888.
One week later the light comes on again. Code is P0304.
Anyone have this happen?

 

You should of came here first. Number 4 will continue to go bad because the dealer didn't have enough experience to properly diagnose. Anytime #3 and #4 are involved, you have to pressure test the coolant system. That's because in MOST cases, the Heater Core lines leak intermittently and at certain pressures (when conditions are met). This type of leak, very often leaves no evidence visible in the engine compartment. So unless your familiar with these engines, you won't know what to look for. This is what most likely is going on now and has been in the past.

 

You paid them $888 to fix your truck, customer paid repairs at Ford dealers are guaranteed for 12 months/12000 miles. Take it back.

 

^^^x2

 

Great! I didn't know that, yea take it back. Pressure test for coolant leaks, specially over #4 or most likely you'll have to bring it back again.

 

Could also be rain water from the back hood channel. If it's loaded up with leaves and tree droppings, clean it out. Check the gasket between the back of the hood and the body.

 

Thanks for the advice. Taking it back Monday.

 

Thanks, GLC. Gasket clean and pliable.

 

Thanks JBREW. I'll mention the heater core lines to them when I take it in Monday. Definitely sounds plausible.