Surprise fix for my dead '02 XLS

[Drewmcg]

Last October I was driving to Chicago on I-94 for a conference when my 'sploder lost power and bogged down on a slight uphill near Kalamazoo. I pulled off the freeway. I looked under the hood, saw nothing amiss. The truck (4.0L) seemed to idle normally. I cautiously continued west on surface road for awhile, before trying the freeway again. It got worse; I pulled off. Trying to start the car in business parking lot resulted in strange clangs and noises. I had the truck towed home and rented car for the weekend.

My regular mechanic recommended "tearing into the engine" to figure out what was wrong (after charging me an hour's labor). I had the truck towed home (again) for the winter, and bought a used '10 with a newly-rebuilt transmission (which I enjoy a lot).

I'd replaced the engine in the '02, and changed the timing chains & guides with quality Cloyes parts, with a lot of guidance from this forum. I'd also replaced the fuel pump assembly, and much of the wiring due to mice damage. New exhuast from the manifolds back (including cats), suspension components, front end parts, alignment, new brakes, new spark plugs and wires, new (aftermarket) coil pack, fuel filler neck, etc., etc., meant I did not want to give up on this truck too soon--but I lack an indoor, heated garage.

A few weeks ago I managed to get it started again (after a fair amount of clanging noise and fits), and did a compression check. Good cylinder pressure convinced me that the timing had not slipped. So I concluded it must be the transmission and/or torque converter, and towed it to a shop that quoted me $2,500-$2,800 for a quality rebuild.

Two days later the mechanic called and said he had diagnosed a failed coilpack, that was cross firing! The coilpack was an aftermarket one installed by my regular mechanic (in lieu of the OEM part, that I don't think was bad, in hindsight). He installed a Motorcraft coilpack and the truck ran great (again).

I'm blown away. How the heck does a coilpack just up and fail after a few thousand miles running down the freeway at 75 MPH on a moderate temperature day?

I wanted to share this just in case anyone here might find this useful. Thank goodness for sharp (honest) mechanics! Drew.

 

[Joe in NY]

Wow... Glad you're enjoying the '10!

Frustrating isn't it??? What happens is the heat, age, and voltage degrade the insulating properties of the dielectric materials in the coil pack. So, a long continuous drive on the highway brings along a good bit load (more air & fuel in chamber which raises the voltage due to the higher gap impedance), age as it's an '02, and heat from baking under the hood from a long drive. Normal wear and tear item but boy does it cause trouble...

Our 1992 Supra used a special electronic ignition by PCM and they are know for failing after 20+ yrs. Our boat would erratically idle, miss fire, and go into limp mode. All due to failing coil packs and the computer trying to protect the engine.

 

[miker104]

I've fixed three Subaru's with OEM coil packs after the original owners spent $$$$ in parts trying to fix them.

 

[TechGuru]

I'm blown away. How the heck does a coilpack just up and fail after a few thousand miles running down the freeway at 75 MPH on a moderate temperature day?

Simple, it was a non-OEM (probably Chinese) one...

 

[Drewmcg]

No doubt. But still, so random! And the OEM part it's made in Spain. I don't think I've ever even seen an auto part from Spain before....

If I needed a coil packfor the 4.0L SOHC, and couldn't afford a new Motorcraft one, goiI'd recommend going to the junk yard and getting a used OEM part cheap. I don't believe they fail very often.

 

[TechGuru]

No doubt. But still, so random! And the OEM part it's made in Spain. I don't think I've ever even seen an auto part from Spain before....

as a MBenz owner I've seen a few Spain parts...

If I needed a coil packfor the 4.0L SOHC, and couldn't afford a new Motorcraft one, goiI'd recommend going to the junk yard and getting a used OEM part cheap. I don't believe they fail very often.

Yep, Junkyard OEM > New Chinese...

 

[410Fortune]

aftermarket coils that are cheap to purchase........ are cheaply made

I had a triton V10, I thought I was doing great when I could buy 10 new coils for under $100!! Well not so much....those 10 coils mine as well have been trash to begin with I was lucky to get a couple of weeks form one of them. Money down the drain.
Cheap ignition coils are not worth it!

 

[Drewmcg]

I recently reviewed one of FordTechMakuloco (sp?)'s videos from about a year ago about re-programming junkyard PCMs as replacements. In it, he briefly mentions the possibility of a bad PCM frying a coilpack. I sure hope that's not what's going on with mine!

Its been running fine for a few weeks since the repair. I took out the new Motorcraft part and swapped it into my 2010 (130k miles); and swapped in an OEM from the donor vehicle for the '02's engine. That part had 116k miles. I don't expect any problems.

BTW, when doing the swap, I managed to break off the tab that holds the four-wire harness onto the coil pack. Its hard not to, as it sits up there above a very hot engine for years and tens of thousands of miles. Fortunately Motorcraft makes (and RockAuto sells) a nice pigtail, complete with but connectors and glue-infused shrink tube insulators, MOTORCRAFT WPT1421. About a half-hour job, for which it is very helpful to have quality crimp tool and quality wire strippers. A heat gun is nice, too. (I had to do this on the '02 a few years back, so I've gotten good at it.)