ggenovez

Hi all,

This should be an easy one for those that have gone through this.

Truck was running great. Rained and got a PO303 error. Pulled the plug wire and noticed moisture on the plug. Swapped it with #7 to see if it followed the plug, took her for a spin and she ran like a dream.

Then this morning started rough, missing, PO303 error again. This time not as bad. didn't rain this morning

Is this just a plug wire problem or do I need to find a way to seal the plug hole?

97 F150 4.6

Thx

Frank_Ford

Take a look at your plug wire and see if it is corroded. See if there is any coolant leaking from the heater hoses that are above that number 3 plug. The heater hose have plastic quick disconnect fittings that become brittle when old. Working on your truck and bumping the heater hoses can cause them to crack and start slow leaks. They are not hard or expensive to replace and neither is the plug wire if it is corroded from water being in the plug socket. You can buy just one replacement wire (i recommend motorcraft and make sure you get the correct length) and the heater hoses on ebay.

side note: I put di-electric grease on my plug connections for a better connection and resistance to water. The plug sockets on the ford engine make them susceptible to water getting into the plug socket from rain, washing the engine, or leaking coolant. The die electric grease is less than $5 at autozone or oriely's.

ggenovez

Thanks Frank,

I did swap plug wires with 3&7 and the problem stayed with 3.

Is it possible it's the coil that's at fault or the plug itself? do the coils go bad in sections or does the whole 4 part coil go bad all at once?

Frank_Ford

It is unlikely that it is the coil because there is not much to go wrong with your two coils. I say this but anything is possible. regarding your plug, more likely to be a problem and it may be that it has just come loose. These plug sockets collect a lot of dirt and oil over the years so instead of just changing the plug, I would recommend cleaning the plug socket first. I use a round wire plumbers brush, WD40 and rags to do this. When clean you make sure your new plug is seated properly when you install it and eliminate a potential problem.

Regarding the plug wire, I take a Q tip and run it in the plug boot. If I find a lot of rust on the Q tip, I replace the wire. I was looking on ebay and there are several people who will sell you a new wire for about $15. There are about 4 lengths for your wire so measure your old one and buy the new one for that length.

ggenovez

Frank,

Thanks for your help. It is the wire. It keeps on popping off.

How did you find it on ebay? I searched and all I could find is the plug set. I need the #3 wire

Thanks again.

Frank_Ford

The Motorcraft part number for the number 3 and the number 8 cylinders is WR-5923. It is 28 inches long. Just enter "Motorcraft WR-5923 spark plug wire" and it should come up.

Before you order it is best to double check and make sure the wire you are replacing is 28 inches long so you know you are buying the right one.