I just changed the spark plugs on my 2000 6v mustang w/ 90000 miles. The plugs I pulled out were motorcraft, so they very well could have been the original plugs. I've been told that the gap will widen as a plug ages. The gaps on the plugs were around .076 as opposed to the spec .054 for the new plugs. Not only that, but when I pulled the plug wire off of four of them, the end of the plug came with it. The break in the metal was rusted so these were not new breaks. Some how the mustang was actually running with this.

Needless to say, the stang seems to run a little better. I assume that I will need to put at least a hundred miles on it for the cpu to adjust to the changes. Just wanted to share this story and see if others have had the same experience with spark plugs.

 

I have a better one. When I got my 5.0 a couple of years ago, first thing I did was a tune up. Now a little info on my engine, it's laid out almost exactly the same as a V6, however, with the extra two cylinders in the front and it being a little wider it is a little harder to work on/with. The drivers side of the engine, which is easy to access, was all newish plugs/wires, but they had platinum tips, and those are generally a no no for Mustangs, so I replaced them with copper tipped motorcraft plugs. Now the passenger side has the EGR system, which makes the back two spark plugs on cylinders 8 and 7 nearly impossible to change. So cylinders 5/6 were also simi newish. Cylinder 7 had serrious corrosion where the spark plug jacket covers the plug, and the plug deffinitly had more wear on it than the rest, however it was still a platinum tipped plug. Cylinder 8, that was the fun one, the spark plug wire basically fell apart as soon as I pulled it off. The spark plug was considerably worn and took about 30 minutes of hair pin turns on my socket wrench to get out (the rust didn't help). The spark plug was the original copper tipped plug that came in the car right out of Detroit back in October of 94, needless to say, it was fried.

But yea, 6 newish plugs
1 old plug/wire
1 original plug/wire

 

I had a hard enough time with the back plug on the 6v, I imagine the 8v back plug would be even more of a bitch. At least I have some cut up hands to prove that I don't just sit at a desk all day.

 

Update === Some how I have lost 3mpg since I changed my plugs. This is the opposite responce I was expecting after installing new plugs. I did not change the wires, but I did lift the hoodle in a pitch black warehouse and did not see any fireworks from the engine.

Any suggestions as to why I would actually lose mpg. from around 23 to around 20.

 

i would recommend replacing the plug wires, and if you haven't change the air filter and fuel filter and then unplug the battery for 5 min and then replug in so that the computer relearns everything and that should help with the mpg's

 

So you changed the plugs and during the whole thing FOUR of the ends from the wires came off and you didn't replace the wires...??? You're not getting all of the spark to the your plug if the ends broke off and you simply shoved them back on.

 

No, the guts of the plugs came out with the spark plug wire. I had to use a leathermen to remove them from the wires.

 

I have a clean air filter on a CAI that I added a few thousand miles ago. I have not replaced the fuel filter although I have been meaning to do so.
With the battery, I thought it would reset by its self after 100 miles or so. Was I wrong about that?

 

you changed plugs and not wires? i always do both at the same time.

 

i changed mine at 70k, original plugs in there, two snapped just like yours, lol

i didnt have trouble getting to my plugs at all, took off my cai and passenger side is open, the rears werent hard at all to get to, just different size extensions