O/T Spark plugs

Oh yeah, that rear plug on the right side is about two feet back under the cowl and that much further back than my arms are long.

The factory original plugs were different for each bank having platinum only on one side of the gap but on different sides because the coils fire one bank with the opposite spark polarity of the other bank. The shop manual says replacement plugs with platinum on both sides is just fine and Ford garages only stock that one kind.

Its the larger Triton engines that mostly have the problem with spitting out plugs but aluminum heads and plugs kept in for many years can be a problem with stripped threads.

Ford admits the plugs can need to be replaced at 75K miles if the engine is driven hard.

The Ford garage thought the check engine light came from a contaminated mass air flow sensor and a slow to react exhaust gas oxygen sensor. I wanted a new serpentine belt, plugs, and wires. The total cost was around $1K. Runs fine now, no check engine lights, no running lean.

Gerald J.

Bosch plugs do not belong in the Ford modular engines. I learned the hard way and so have several other people.

Do not get caught up in the hype of their 2 or 4 point platnum plugs, a case of marketing over engineering.

Does your 1998 have Coil on plug? Here's the instructions on how to change.

Link

You must use a torque wrench when changing these plugs no matter what type of plug wire. The aluminum heads will strip the threads and you won't even know it until you blow the plug out the hole a mile from home.

For ideas on what plugs to use look here:

Link

The mechanics I've talked to say the manufacturer's recommended plug is usually the best for a 4.6/5.4. If you have problems with misfires after installing the new plugs the problem is usually in the ignition system and the best, most exotic, most expensive plugs in the world won't cure it.

Go for the best and forget changing them in the long run they are a lot cheaper.
Walt