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My Ford 302 was misfiring.

Iron Woode

Iron Woode

Elite Member
Super Moderator
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.

 
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.
 
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.

 
Originally posted by: Subbaculcha
Oil fouled? Could be a valve seal.
Click to expand...
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.
 
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. :|
 
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. :|
Click to expand...

DOH!
 
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.
 
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. :|
Click to expand...

YIKES!:Q
 
Originally posted by: Iron Woode
Originally posted by: Subbaculcha
Oil fouled? Could be a valve seal.
Click to expand...
It was hard to tell because the plug had stopped firing for a little while.
Click to expand...

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.
 
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.
 
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