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Discussion Starter · #1 ·
This is on a 2002 Focus SE wagon with a ZETEC motor.

The car is showing a P0304 code, cylinder 4 misfire. This morning I measured the resistances on the coil and the plug wires and all are within specs.

My next step was to check the #4 plug. I usually use a T-handle spark plug wrench to remove and install plugs. The plug is too tight for this wrench to turn it, even with a bit of extension. I tried another plug and had no problem removing it. I've read that the misfire might be related to the over tightening.

The plugs were installed at a shop about 2-3 years ago. The threaded part of the plug is fairly long, so I don't think there's much of a chance of it being cross threaded, just over tightened.

So the question is- What are to odds that I can just use a bigger wrench and remove the plug without any damage? Or is there a better way to try to loosen and remove the plug?

I would really hate to remove the plug and find the threads in the head damaged and not be able to install a replacement plug. I don't have the capability to repair that.

Thanks for reading,
George
 

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Discussion Starter · #3 ·
I wouldn't put anything else in that hole. Adhesive Teflon, thanks for the reply. I'm thinking that that's probably what I'll do, just try to loosen it and see what happens.

What do you mean by "I wouldn't put anything else in that hole"
 

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When I had one like that, I sprayed liquid wrench into the hole and let it soak overnight. Then with a hammer, I tapped counterclockwise on the end of my ratchet handle to shock the plug loose. With some patience it finally worked.

When removing plugs, it's hard to control your arm strength with a short ratchet handle. I use a 2 foot cheater pipe with mine. The extra length makes it easier to "feel" a safe level of torque.

When installing plugs, I use the ratchet handle (alone) with three fingers until snug. A torque wrench would be better but I've not broken a plug yet. Or had one work loose on its own.
 

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It's an angle torque plug with no selaing washer. They don't have to go in very tight and one of the characteristics of the plug angle seal is that many will self tighten in use, they come out much tighter than what you originally tightened them to. The heat cycles of engine operation do it.

Anything OP read about overtightening a plug making it misfire is bunk unless the overtighten damaged it, one can always crack the insulators. That comes more from using the wrong kind of socket at installing them.
 

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Discussion Starter · #10 ·
It's an angle torque plug with no selaing washer. They don't have to go in very tight and one of the characteristics of the plug angle seal is that many will self tighten in use, they come out much tighter than what you originally tightened them to. The heat cycles of engine operation do it.

Anything OP read about overtightening a plug making it misfire is bunk unless the overtighten damaged it, one can always crack the insulators. That comes more from using the wrong kind of socket at installing them.
Thanks, amc49. The idea that the plug self tightened over time makes me less concerned about trying to break it loose.

I had read that over tightening could crack the insulator, or could cause the insulator to separate from the metal of the plug.
 
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