StanglovR02

I had a bad coil couldnt figure out which one despite using multiple tests so I went to pick and pull and snagged 8 out of a mountaineer. cost me under $80 for all 8 of course the guy said they were all compatible with all 4.6L. car runs well but just checkn im good

school boy

yes the coil packs should be the same.

DeathRattle

Here is a good way to check your COPs...for future use:

1st) Have the ECU scanned. Even if a light is not on you still may have a code in there.

2nd) You can isolate the bad COP by starting the engine, popping the hood and listening to it run. Then disconnect one COP and listen to see if the engine starts to stumble or run rough. If it does then that coil is fine. Reconnect it and move on to the next coil. If you remove a coil and there is no change in the way the engine runs, then more than likely that will be the bad coil. But just to be sure, you want to go through all the coils. Disconnect each one (one at a time) and take note of engine changes. Once you have isolated the coil(s) that had caused no change in the engine when removed, then you replace the coil(s) and see how the engine runs.

This is a good test because if your engine is running rough due to a bad coil, then removing that coil will cause very little to no change in the way the engine runs. If the change is very little, then you can still isolate the bad coil by comparing the engine change to how the other coils affect the engine. The good coils will have cause a significant change in how the engine runs when they are disconnected. The bad coils will only have a small change or no change at all.

Also, while you have the coils out you might wanna look at and/or replace your spark plugs.

StanglovR02

thanks for the advice Deathrattle. I did actually run this pior to replacement. also pulled all the plugs which were only 8k mikes old and checked the gaps all checked out. thr problem with that test is theres 8 cylinders and its difficult to determine when 7 are still firing. must easier and effective on a 4cyl. did run the OBD and determined it was a COP but not which cylinder. i noticed some cracking at the base of a few of the boot which would cause a ground

cliffyk

Cracked boots will allow the coil's output to arc to the plug well which causes misfiring as well as causing the COP to overheat and burn out.

The COPs are not designed to ever repeatedly dump their full charge, in fact using a bench tester of my own design I can burn out a OEM COP by rapidly firing it across a 5/8" air gap. After 12 to 15 full dumps it will be so hot you cannot hold it in your hand, after 20 to 25 the smoke comes out. The aftermarket COPs I have tested can only withstand 18 to 20 full dumps before they burn out.

For more than you probably want to know about COPs click here--from the Mods for Beginners sticky...