Coz84

I have a 1997 4.6 f150 with a vortech supercharger it had a misfire, I changed the plugs and wires and the check engine light went off and drove great but when I floored it at the top of the Rpm's it started to clatter and it stared missing again and the light came back on. The clatter stopped and it idles fine but is still missing I'm wondering if a bad coil could cause the miss or if there is a more severe problem that caused the clatter

Frank_Ford

I never say never but, those coils on your truck don't usually go bad. More likely you have a bad connection somewhere or one of your spark plugs has come loose. I have found that often those spark plugs from manufacturers other than motorcraft will often come loose.

First, I would check the codes if the check engine like is on and find the cylinder where you have the miss. Then check the spark plug and the wire connections at the plug and the coil. I like to use di-electric grease on the plug wires both at the coil and the plug to make sure I get a good connection. (cost less than $5 at Autozone or others).

If it is a loose plug and not a motorcraft plug, I would buy a motorcraft plug and put it in that cylinder. You may have some threads that are a little worn and allowing that non-motorcraft plug to come loose.

Those plugs like Bosch etc are good but I have found that will come loose in the heads of the 4.6 V8. I have never had a problem with the motorcraft plugs coming loose. I have mixed bosch and motorcraft in the same engine without noticing any difference in performance so I don't think you need to replace all of them if you have just spent money to change all your plugs.

totarella

Yes the coil could go bad, I've replaced four on mine in the past 6 years owning my 97 5.4 . I heard the 4.6 engines had one or two coils but mine has 8; one for each plug. They go bad over time like anything does. Good luck, if you need to test them I'll get you the procedure I used for my truck.