It doesn't Look Good...black plugs
 

My #8 cyclinder is turning plugs black.
Went back to Ford to hook it up to their computer. I was hoping it was an injector stuck open, but they ran a injector pulse test and they were functioning fine.
So they are saying it could be a few things.
1. A bad piston ring: I am bringing it back on Wednesday to do a compression test
2. A bad valve: which I guess if it passes the compression test I will have to pull the head.
3. The rocker fell off: which I guess I would see if we take off the valve cover.

I still have miss fire in banks 5, 7. and 8.

Does anyone know if SVT is call to replace a head with a bad valve?

Has anyone experienced anything like this?

did they do a "relative injector flow test"?

they should be able to measure each injector's flow in miliseconds to determine not only is it firing electically, but that it is flowing the correct amount of fuel.

also, have them do a cylinder leakdown test on that cylinder when they do the compression test before they pull the head.

BTW, if it threw a cam follower, it'd likely be noisey as crap, or at the very least probably would have made noise when it came out. having said that. it's kindof rare for that to happen. if've seen other motors do it, but not a 4.6/5.4.

good luck.

later,
chris

I beleive they did the relative test. I saw the computer and it look like it was ready how much each injector was flowing.

However the computer would not let them do a relative compression test. Said for some reason it was not giving him the option


Thanks for the advice, I will have they do that test.

Sucks about you problem but what is the dealer gonna say about all these \/

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WOW, that sucks..... :(
keep us posted ?

It won`t pass the compression test with a bad valve. A bad or leaky valve would cause a low or no compresion condition.

So if the piston ring is bad or a valve is bad, both will fail the compression test??
Thanks

I'm pretty sure thats right. Then you put some oil down the plug hole and check again. If the compression comes up you have bad piston rings. If it doesnt come up, then its somewhere in teh valves. How much are they charging for a comp test? You can do it yourself pretty easy, my tester cost me 30 bucks or something. No worse than a plug change.

Not sure what they are charging me. The guy said if what ever is broke can not cover by warrenty then I would have to pay for 1 hour of their time ($95). So far I have been there twice for about 3 hours total and not paid anything. I am bringing it to them because there is much more wrong than the lean code the computer is reading.

I think I may do it myself. I just pulled my plugs 3 times this weekend trying to figure this out so what is one more time.

One question:
Do I have to remove all plugs to just check the compression on the #8 cyclinder?
Thanks

you should, you should be comparing them from cyl to cyl there was a thread on this a couple days ago.