Difficulty to change spark plugs & wires 1999 Ford Expedition

How difficult is it to change plugs and wires caps etc.

IIRC the 1999 Expedition has COP ignition, it doesn’t have a distributor or a distributor cap, or even traditional plug wires. The spark plugs are the only thing you’re going to replace.

First, carefully remove the coils. Then blow out the plug wells with compressed air. They should be dry. Using a 5/8" deep socket, 6" extension and a ratchet, carefully remove the plugs. If they have been in there for 100K miles, be gentle with them, the aluminum heads will not tolerate any abuse. Do not force any that resist turning out freely. If they feel “sticky”, stop, spray some JB Blaster in there and work them back and forth until they free-up. When installing the new ones, apply anti-seize compound to the threads.

The rubber boots and contact spring and resistor can be removed from the coils and inspected, but if the truck was running OK beforehand, that is not necessary. Do not over-tighten the small screws that secure the coils, the manifold is plastic and the threads strip very easily…Put everything back together the way you found it. Now is a good time to clean the MAF sensor and throttle body. Special cleaners are made for this purpose…

On that note, extreme caution needs to be excercised, or so I’ve heard from a mechanic that changed all my plugs. I wanted to do it, but time was an issue for me. This mechanic said that sometimes these plugs on these particular models can break. I think he meant where the porcelain meets the nut/bolt part of spark plug.
Be prepared for your truck to run rough sometime. You may get lucky. We have a 99 Ex. as well. The coils started going out. They seem to be sensitive to the touch. Nothing happened til I replaced the plugs. I’ve replaced 3 coils so far and would like to replace the last 5. It’s such a hassle to have a coil go out b/c not only does your C.E. light come on, but it runs rough and if it’s as bad as when our last coil went out, you could smell the fumes from the exhaust. The light actually started flashing at my wife and she turned around and came home. The mechanic said its a good thing she did, b/c the O2 (?) sensors were sensing an unusual amount of unburnt fuel in exhaust and was trying to alert you to stop and that it could be an explosion hazard given the temp. of converter.

Anyway. The coils are about $40/ea., or at least that’s what they cost here. What I paid to have one done was $150.00 parts included. Needless to say, I started doing it myself. It would’ve been $500.00+ to do all the rest!

Take your time with it. The only difficulty is the ROOM you have to work with. I have big hands so its hard sometimes. HERE’S A TRICK I LEARNED!:

When you’re working in such tight space and trying to put a coil back in (like cyl. #8, right on back of motor drivers side) I kept trying to put coil in and then bolt that holds coil down. It’s such a tight fit I couldn’t get back there with bolt and I ALMOST lost bolt. WELL, I GOT SMART… pulled the coil back out and put bolt through hole of the coil first then weaseled coil back in. WORKED! ALso, I always turn bolts/screws counter-clock-wise until I feel threads “Click” then I go foward with it. This helps ensure that you don’t cross thread.
Good luck.
Let me know if you have other questions on these Exes. We still have ours and I love it. It also helps to have a book. That’s helped me figure out cylinder numbers.


I just wanted to emphasize this line by JPKansas:

“ALso, I always turn bolts/screws counter-clock-wise until I feel threads “Click” then I go foward with it. This helps ensure that you don’t cross thread.”

This is an incredibly valuable line to remember whenever you are working on your car. NEVER force a thread.


If you want to buy a few of those coils in a hurry (they are $69 each in Denver) just clean your engine off with a pressure washer…