I have no service manual, but i do know i have a code p0304. I would like to replace the plug but dont know which cylinder is #4. It is a '99 F150 with a triton 5.4L. Also, in doing searches on this forum i hav enoticed allot about plug wire resistance, it seems to me there is no "plug wire" so to speek. It looks like #16 gauge normal wire going to a plug on the coil.

 

Cylinder arrangement
Ok I found out that cylinder 4 is rear, passenger. I also found out that on 1999 there is a heater hose leak problem that can fry the coil. I don’t see any anti-freeze at the present time there so I doubt that is the problem, but I may be wrong. Is there a way to test this coil? After reading I found I have a COP (coil on plug) new to me. Where is the distributor cap(J/K)? I also recently ran out of gas (almost) so it may be clogged injector, ouch. Is there any way to self clean the injector if it is clogged?

Thanks in advance,
i am used to working on older engines

 

I haven't messed with the COP system yet since I have a 97 4.6. If all the cylinders use the same coil you could just swap #4 with #3 or some other one.

 

You will almost never see coolant on plug #4 because it evaporates so quickly. But I would bet money/beer that the hose is leaking on your coil.

Just look right above the #4 coil and you will see a rubber hose attached to a aluminum hose. If you have a factory style "Pinch" clamp you need to replace that with a "screw" type hose clamp to stop the drip.

There is no distributer on any of these trucks. The COP and the plug and wires on the 4.6's are run by the computer which knows when to fire each plug based on many different sensors. But mainly fires off the crank position sensor.

Don't waste your time trying to test that coil just replace it. (After you fixe the leak of course)

 

What type of connction does the hose have to the fire wall? It seems to pivot like it's loose, and I see no clamp on it at all, but there is a screw clamp to the other end of this same hose from an aluminum elbow to the engine block that is very strong. Is the connction at the firewall called a crimp connection? If so, seems very loose for such a critical system.

Checked #4 plug and it had rust all over it, so I suspect a coolant leak from this hose from the firewall. I changed the plugs less than 6 months ago? What do you think ???

 

Valk1500-

Did you ever find out if the coolant is what caused the rust. I replaced my spark plugs last night and my #4 was completly rusted.

Thanks!