after i replace my spark plugs i used motorcraft plugs and used the old wiring which were bosch i believe and probably in august 3 months after plugs replaced i was driving and truck had a misfire and CEL was flashing happened to be a loose plug cable. and it would happen here and there. just today i was driving on highway and noticed it came off so i pull of the road and saw which i believe was the second or third cable off bank 1 but the whole cable was up it wasnt too far from the whole thing coming out the hole. but the first time it was a loose cable from bank 2. so im stumped could there be blowby escaping through the plugs

 

sorry forgot to mention its a 97 with a 4.6L with almost 140k on it

 

Since you have wire on plug design, you may have to take and squeeze each wire end where they go on the plugs. It sounds like the connector inside has stretched a bit, so it doesn't hold itself on the plug end. It's very common. When you pulled the plug wires off the old plugs before they were probably stuck somewhat and yanking them loose tend to make the ends wallow open causing this problem you are describing. Just be careful if you use plier without a piece of cloth around the outside rubber, so that you don't cut the silicone boot and then get a plug arc to the head. Just do it easily and just hard enough to bend the inner aluminum or copper connector to that they are a bit smaller. They should click when they go over the plug end and are fully down. Good luck.

 

I have been having this same problem with my 4.6 since I changed spark plugs a few weeks ago, only on cyl 3. I'll have to try cramping the wire end. Thanks!

 

so today was even worse the same cylinder. i started engine this morning and as i was leaving for work i could tell the boot came off cause it was running like crap. checked it was the same put it back on i was driving i past three or four houses on my street and again. so i turned back went home. i tried tightning the plug kinda a bad move cause it was fairly warmed up engine but i had no choice i had to get to work. i also tried crimping the connection and after about 30 mins in freezing weather it seemed to be fine. after 40 miles that i drove today it held up

 

Why would you tighten the spark plug if the boot was coming off?

 

i was thinking myabe the plug was loose and it could be leaking combustion through plug and causing it to pop off.

 

So are they staying on now or what?

 

they actually are i drove probably a little over 100 miles and they running good.

 

Glad to hear it.