locorider21

ok, so the other day i was switching spark plugs, 5 of the 6 went in fine with no problem. the sixth one went in half way before stopping.. after looking into it some more, the thread was all stripped inside. so i had a mobile mechanic come out and re thread the hole. He tapped it and re threaded it and cleaned up the shavings and put the new spark plug in.. when i started the car, it starts now and idles, but it idles rough, and the second i switch it in gear, it idles even rougher, and if i push the gas to move, it boggles , it moves, but it sounds like its gonna shut off.. what could have happend? ive checked all the spark plugs, there tightned correctly and the cables are connected right.

Whitehorse10

What kind of spark plugs did you use?

2005Redfire6

So you have shavings in your motor now?

locorider21

well the mechanic who did the rethreading, cleaned out the cylinders pretty well, he used compressed air to at the end to get it all out, so i dont think there is ... BUT it is a possibility.

and i used bosch platinum spark plugs

have been without a car for a week now, finally broke down and had the car towed to ford today.. i know its gonna drain my pocket... ill find out whats wrong for sure tomorow

2005Redfire6

How could compressed air pull shavings out of a spark plug hole? I'm not busting your ***** jw.

locorider21

tru.. well i guess if ford comes back and says that they found metal shavings in a cylinder, or a cylinder was damaged, ill go after the mechanic who rethreaded the hole.... but would metal shavings in the cylinder cauase the engine to act up that fast?

Whitehorse10

I have read other threads about Bosch spark plugs having issues after installing them in the 4.0 engine. As far as the shavings go, yes they absolutely can cause damage in the engine. The larger the shavings, the more damage they will cause as they get ground into the cylinder wall during engine operation. I would never have tapped out a spark plug hole with the head still on the engine personally. Also, anytime you change your plugs you should have a can of compressed air on hand to blow debris away from around the plug before you remove it so that it won't fall into the open plug hole once the spark plug is removed.


The fact that the plug messed up your threads leads me to wonder if the problem with the Bosch plugs is that they don't seat exactly properly into the plug hole opening and as a result just enough air is pulled past the plug into the chamber to cause a rough idle. Just a theory, what do you think redfire?

Whitehorse10

By the way locorider, check this thread out. Sounds like your problem.

https://mustangforums.com/forum/v6-s...ugs-annnd.html

2005Redfire6

I've always heard about the 4.0's being tempermental with the spark plugs you put in there thats why when I replace mine I'm going to replace them with factory ones...