03gt04mach1

First time I've ever heard of this. But, there is ALWAYS a first time for anything.

stealth_GT

I no longer have the Vortech on though...

not saying that the loose terminal nuts would cause the misfire necessarily, but it was idling pretty badly. I also found one broken and one right about to come apart

contentsunderpressur

Yes now being broken or cracked will surely cause those problems. It only takes a small crack for the fire to jump out the side of the plug.

stealth_GT

I wonder how long they've been bad.. I hadn't run the blower since October. Had them on the car since summer of 09. First time I checked them.. I will make it a routine to at least check the gap every few months, as well as the over all condition...

Detroit427

No, you found the issue. It was loose terminal ends. Certainly improper gap can cause problems but this can too. Loose terminals reduces the surface contact/connectivity, like an mini air gap between the threads which reduces the strength of the spark getting to the cylinder.

I just discovered this with the Brisk plugs in my car. Since fall last year I started noticing I'd get an intermittent miss especially at cruising speeds or just lifting the gas slightly and it was getting to the point where it was starting to do it on acceleration too. When I first installed the plugs a few years ago I noticed the ends were loose right out of the box, so I tightened them as much as I could by hand and I thought that would take care of that, apparently not.

I re-checked the gaps a couple months ago and they were ok .035" so I re-set them to .032." The plugs looked fine. That seemed to help but never totally cleared the miss then it got worse but never enough to ever throw a code. I was starting to think I had a COP going bad.

So I decided first I'd replace the plugs since they had about 15k miles on them and they were due to be replaced. When I removed them (this time removing them from the socket) I noticed almost every terminal end was loose.

Replaced them with new Brisks (this time the terminal ends were tight out of the box), set the gap to .032" and it's running great now. I'll be checking for loose terminal ends everytime I check the gap from now on!