1997 4.6. I keep getting code po307. Misfire cylinder 7- always because of water in spark plug well. I replaced the wire and boot- that seemed to help for 400 miles. Recently it started again. So I bought a new spark plug.

That seemed to fix it. The old spark plug was only 3 months old and let me tell you it looked like OE.

What could cause me to have problems with only this cylinder? Im sick of tearing the thing apart and replacing parts since it always seems to start back up again.

Should I just never drive in the rain?

 

Just to be clear where is the location of the plug that you are calling #7? Passenger side, driverside and how many back from the front? Not trying to be a smart *** but just being sure that your #7 is the same as Fords #7. Usually #4 on this vintage 4.6 is the problem. Also have you checked the other plug holes for water as well? Sometimes a single code won't tell you the whole story. Also driving in the rain normally won't cause a problem but washing the engine often can. Take care.

 

7is a problem for me as well. Must be on some trucks that one gets allot of road water. Make sure you use dielectric on the wire..

 

jethat why didn't you jump on this sooner, could have saved me from writing a short novel

 

4 8
3 7
2 6
1 5


? Right? I never wash the engine. Hell it hasnt even rained hard in forever here...

I heard it could be one of the hoses leaking onto it, is this true?

 

you have it right 1 on the passenger side. There arnt any hoses above it. gotta be road water or a leak in the intake manifold gasket.

 

Yep, that's the right order. Also the leaking hoses is usually #4 like dynotech said I believe. That's right below the heater core hoses, that can leak sometimes. I would take jethat's advice and dielectric grease the boot to seal it against water.

- Erik