My Ford 302 was misfiring.

[Iron Woode]

My 1987 Ford Crown Vic was misfiring and I figured it was a bad sparkplug. So I went and got some new plugs (NGK) for it.

Since it is easier to change the plugs on the Driver's side, that is what I did. Lo and behold, I found the bad plug on cylinder #8.

Now, this is the third time that that cylinder had a plug go bad. Is there something peculiar about #8 cylinder in 302s? Anyone else have issues like this?

Thanks guys.

 

[DaTT]

From what I understand, or once heard, number eight plug always fouls. I heard it was because no one changes it because it is the hardest one to get at....but reading your post tells a different story. I also thought #8 was on passenger side.

 

[Subbaculcha]

Oil fouled? Could be a valve seal.

 

[Iron Woode]

Ford numbers their cylinders from the bank that sticks furthest towards the front of the car. The banks are slightly offset. The one closest to the front starts as #1 and so on.

 

[Kadarin]

Originally posted by: Subbaculcha
Oil fouled? Could be a valve seal.

Or piston rings.

If the problem persists, as a temporary fix you could try reducing the spark plug gap.

 

[Iron Woode]

Originally posted by: Subbaculcha
Oil fouled? Could be a valve seal.

It was hard to tell because the plug had stopped firing for a little while.

I had thought about valve seals too. I don't have the proper tools to replace them, so I wll look around to getting someone else to do them. With the compressed air adapter to hold the vavles up, the seals can be replaced easily.

I would rather not have to remove the heads.

 

[cavemanmoron]

hooray!!

I had a car once,that was running crappy.
it needed exhaust,so I took to a muffler shop had Dual exhaust put on;
sounded worse.
Put new plugs and wires on,one plug and wire at a time. No help.

Tokk the heads off,tok to a machine shop,found the heads were bad.
Bought set at junkyard,and took them to machine shop,
had them redone,reinstalled "new" heads.

Still had misfire!
Turns out that 2 plug wires had been swapped by the previous owner!
Arrggghh. :|

 

[nakedfrog]

What did the plug look like when you pulled it? Pics?

 

[nakedfrog]

Originally posted by: cavemanmoron
hooray!!

I had a car once,that was running crappy.
it needed exhaust,so I took to a muffler shop had Dual exhaust put on;
sounded worse.
Put new plugs and wires on,one plug and wire at a time. No help.

Tokk the heads off,tok to a machine shop,found the heads were bad.
Bought set at junkyard,and took them to machine shop,
had them redone,reinstalled "new" heads.

Still had misfire!
Turns out that 2 plug wires had been swapped by the previous owner!
Arrggghh. :|

DOH!

 

[TwoBills]

If the plug is fouled w/oil you can always move to a hotter plug in#8. Or widen the plug gap. That'll give you more fire, thus burn a little hotter.

 

[Ornery]

How do you know it's not a bad wire, or distributor cap?

 

[Linux23]

Originally posted by: cavemanmoron
hooray!!

I had a car once,that was running crappy.
it needed exhaust,so I took to a muffler shop had Dual exhaust put on;
sounded worse.
Put new plugs and wires on,one plug and wire at a time. No help.

Tokk the heads off,tok to a machine shop,found the heads were bad.
Bought set at junkyard,and took them to machine shop,
had them redone,reinstalled "new" heads.

Still had misfire!
Turns out that 2 plug wires had been swapped by the previous owner!
Arrggghh. :|

YIKES!:Q

 

[So]

Soon to be simply 'on fire' :evil:

 

[Subbaculcha]

Originally posted by: Iron Woode

Originally posted by: Subbaculcha
Oil fouled? Could be a valve seal.

It was hard to tell because the plug had stopped firing for a little while.

If it was valve seals or rings plug would be oily. If not oily Put a new plug on and check for spark, could be electrical problem.

Yup, seals are not that hard with the right tools.

I'd also do a compression test for the hell of it if it's oily.

 

[kponds]

I had the same problem on an 86 CV - replaced the plugs several times. Come to find out, it was a leaking intake manifold gasket which finally solved the problem. I put about 200K miles on the car and I bet I went thru 6 plug changes and 2 intake gaskets. Not sure that this is the answer for your problem but it was for mine.