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Misfire Cylinder 3 after changing new spark plugs.

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#61 ·
carney714 said:
oh!. and when looking at the spark plugs i notice alot of black around it... Might not mean anything. but since they are a week old, im just curious
carbon?
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Do you mean when you look at the electrode part that goes in the engine? Is it only on cylinder 3 or all of them? If they are all black you're probably running rich. And if you made 415hp I'm gonna assume you're using forced induction? That can damage rings. What happens is if the rings weren't gapped properly and the car was driven hard, the rings will expand and the ends will meet and sieze on the cylinder. When the piston moves them after that they will crack.

And yeah, to do rings, you have to pull the head anyway, as well as the pan.
 
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Discussion starter · #62 ·
yeah all of them are black. They are gapped at .035 which is the right size correct?
Using Ford Racing Spark plugs


And forced induction. Not sure. Got the car already build
can this be done with the engine still in the car?
 
#63 ·
forced induction means supercharged or turbocharged. I'm not getting a warm fuzzy the more we talk about this.
 
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#65 ·
Yeah, at this point it's sounding like you might have a broken ring. From all of the numbers you've provided that would be my best guess. That sucks bro.
 
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#67 ·
Yeah, if you've got a bad ring you're basically pissing fuel in and not using it, so your mileage will suffer. And yes, unfortunately you're pretty much looking at a rebuild. Depending on the mileage on the engine you could just rering it and put it back together, but you still gotta tear it apart.
 
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#69 ·
With that low of mileage I would just buy a set of rings and rering it. Get a gasket kit, pull the motor, pull the pistons out, change the rings, reassemble. Put every part back where it was. It'll be fine. Just make sure to gap the rings with enough room to grow.
 
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#71 ·
I'm sure it will a bit, probably not so much that it's like a kick in the butt though.
 
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#72 ·
I say throw in some rods and pistons while your opening the motor up
 
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#73 ·
Did you hear it out of the dipstick or oil cap, exhaust or intake?

If its a ring its gonna make the oil fill cap/dip stick whistle/howl

If its a stock short block you prob busted a ring land, very common problem on boosted cars with stock short blocks
 
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#74 ·
I cant see a 53% leakdown with the comp number so close. No one has mentioned it but the correct procedure for a comp test is a engine @ operating temp, remove all plugs, hold throttle wide open when turning over, and turning the engine over approx the same number of revolutions per cylinder.

Any detonation on stock rotating assembly equals broken ring lands. This also will mean lower compression, which you do not have, and you will see blue smoke from the tailpipe when under a load accompanied with some oil loss.
 
Discussion starter · #76 ·
I had cylinder 3 at TDC and had a huge leak. Couldnt pinpoint the leakage. Did the test 3 times


Now I can redo the test to try and find the area it's escaping from.

Would I need to remove the other spark plugs to test cylinder 3 only?

Had the throttle open.
 
#77 ·
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