Originally Posted by BrianW
I just had the plugs on my 98 5.4 replaced by the dealer at 89,000 miles. I wondered at the time if I should have proactively replaced the coils, but decided against since I have had no problems to date. Is this a "if it ain't broke don't fix it" scenario, or am I on borrowed time? We're likely doing a month-long XC trip this summer from east to west coast and back, and I'd rather have my local shop do it than some random guy in the middle of Kansas. Thoughts? Are they hard to do yourself if the plugs have already been done?
Taking my own experience into consideration OEM or equal quality COP's aren't subject to short lives, repeating one of my E250's has just over 275K miles and still using original COP's. Were it me (and it has been) I don't proactively replace every COP because one has gone bad or a certain mileage has been reached.
Replacing the COP's and their boots is fairly simple but of course that's subjective pretty much 100% dependent on your DIY skill level and tool compliment. The only real challenge is access to the parts as they reside in or on the engine somewhat buried and difficult to see the first time. Various plumbing and electrical wiring run close and in some cases right over top; the fuel system rails (fuel lines for injectors) are extremely close too.
I have and do change COP's with nothing more than 1/4" drive tools, specifically normal ratchet, 6" or 8" extension & 7mm shallow socket. Optional tools to have around would be a universal joint and a 3" or 4" extension as well. Ahh yes----an extendable magnetic pick up tool would be pretty invaluable too.
Over on FTE I posted a bit of a tutorial showing how to address access to the #8 plug/COP/boot on the 97-03 5.4 motors. That particular plug has just about every restriction and impediment in one spot while the other plugs have one or two of these issues---its a good learning experience. By comparison the remaining plugs are quite "easy".
My first forays into changing these parts was the learning curve for me but that's long ago past. Today when a COP fails my biggest hurdle is overcoming laziness to make the simple swap. (I have two different E250's so there's always something to drive.
I'm not a genius, not a full time mechanic so in short if I can do it and you're sufficiently motivated changing plugs and/or COP's is reasonably within the doable range for most van owners. Anyone looking to do this is more than welcome to contact me for specific info about the modular motor plugs. Small warning though---I'm more familiar with the V8's although the V10's are similar enough in this area that the info transfers well.
I'll add if one only reads all the what can go wrong, instances of difficulty some have experienced and only look at a modular motor from the perspective of attempting repairs it does seem quite daunting. In truth once you've done this just the first time the learning curve is pretty much over, the mystery and fear of DIY also disappears. In the medical world (Grey's Anatomy for me) its said "watch one, do one, teach one..........." and that applies to COP's and plugs in our beloved Ford motors.