Engine Coils-Prophylactic Replacement??

[JOD]

I'm getting ready to do the plugs on a Ford w/a Duratec V-6. This involves removing the UI manifold to get to the rear 3 plugs--which involves removing a fair bit of other stuff, and will probably take me a couple of hours to do the whole job.

The car has 75K on it and is nearing 5 years old, so it's definitely time to get the plugs out of there. Here's my question: should I just replace (at least) the 3 rear ignition coils while I've pulled everything apart? Do ignition coils (coil-on-plug on the Ford) actually 'wear out'? I was figuring I could just test them with a multimeter (though I can't find a voltage spec anywhere), and if they're all close to each other, assume they're fine.

I don't want to do this just to then pull the UI manifold off again 2 months later--but I don't want to needlessly replace parts either. I was under the impression that it took an event to ruin a coil, but that they really didn't wear--so changing them in anticipation of trouble would be a waste. I don't really know if this is true or not, so if someone has more knowledge on the subject I'm all ears.

Thanks for reading, and for your advice!!

 

[The_Jeff]

On the 4.6 V8s they suffer from cheezy chinese coils. I would go motorcraft or go home.

Sometimes the boots rot while the coils remain electrically fine. They just short to ground when they get wet. IDK if they're seperately replaceable on your coils.

If it were me I'd leave it alone. You'll be better able to do the manifold a 2nd time if necessary with experience from the first time.

 

[JOD]

Originally Posted By: eljefino
On the 4.6 V8s they suffer from cheezy chinese coils. I would go motorcraft or go home.


Funny, that's the other question I had, but I didn't want to overload with stupid questions! I was wondering if there was a difference between the Motorcraft coils and the no-name coils. I was wondering if they all came from the same place, re-branded, or if there was a difference.


Originally Posted By: eljefino

If it were me I'd leave it alone. You'll be better able to do the manifold a 2nd time if necessary with experience from the first time.


HA, funny you say that. I was actually kinda thinking the same thing. It's mainly an issue of disconnecting a lot of stuff, so it probably would be easier the second time around.

Sounds like a plan. The boots are integrated on these, so I'll visually inspect them, test them on a multimeter and probably stick them back in if they look OK.

Thanks for the response!

 

[ForestGrump]

What year is your car?

anyway I have a 2003 Mazda MPV (Duratec 3.0 V6) where one of the coils went out. At first I would get a slight misfire and eventually it threw a code. I replaced the spark plugs and things were much better. Thought I fixed the misfire problem..until it rained.

So the day it rained it threw a misfire on cyl 6 (i think). So...I bought new spark plugs and 3 new coils. Gapped the plugs, put them in. Put 3 new coil packs on the back (no point having to take the manifold off to get to the bad coils right?). Anyway, it no longer misfires and I have 2 spares for when the other coils go out.

so yes, I would buy 3 new coils. Put new ones in the back so you know they're good. Keep the old ones to replace the ones in front as they wear out.

 

[JOD]

It's a 2005, so I think our engines are pretty similar.

I should mention I'm having no known issues right now--no codes, and it's running great. While the plugs aren't 'due' until 100K, I'm thinking it's time to get them out of the head before they become permanent equipment....

 

[Christian_89LSC_96XJR]

I would. On our Jaguar S-Type (Duratec related V6) you also have to remove the intake manifold to reach the right bank spark plugs and coils. I already purchased a set of three updated original Jaguar coils (3rd version - the earlier ones had problems) and will install in place of those coils. I will leave the left bank coils in place (and have the other 3 old ones as spares) as these are easily accessible and can be changed in a few minutes.

 

[ForestGrump]

Well, the van started acting up around 60k. It's a common problem on the Mazda MPV for the COP to go bad from moisture. Later revisions of the part had a little hole to vent moisture out.

Now, I know Ford and Mazda have lots of parts sharing and wouldn't be too surprised if both our coils are bin parts. However, they do have their differences even within the same platform (look at the Mazda6 and Fusion engine components). And your car is 2 years newer, so there could be yet again another round of parts revision/refinement/component cost cutting. Take what I say with a grain of salt.

I would suggest trying a car specific forum and see if these coils routinely go out between 50-100k. If yes, then might as well put new coils in there and just have to replace the ones in front, which is easy to do (yay no manifold removal).

 

[JOD]

Originally Posted By: ForestGrump

I would suggest trying a car specific forum and see if these coils routinely go out between 50-100k. If yes, then might as well put new coils in there and just have to replace the ones in front, which is easy to do (yay no manifold removal).


Well, that was the great thing about owning a Volvo V70R, and the bad thing about owning this car.

I've probably learned more about the Duratec engine from reading the Mazda forums, even though they aren't identical (particularly the heads). A Ford Freestyle just isn't a car that brings out the car enthusiasts, and I think Ford sold about 30 of these, so there's a real dearth of information out there...

Your experience goes right to the heart of my question, though: you had something go wrong that led to a coil going bad. Wouldn't it be possible though that the same event could affect a brand new coil the same way? And would having new coils in there really help the situation? Basically I was wondering 'how do they go bad'. If it's moisture, then I guess inspecting the boot would be a biggie. They seem like binary systems to me--they're working, or they aren't. That's why I'm wondering if a multimeter test (and inspecting the boots, as another poster mentioned) would suffice. Or, could the internals actually be subject to wear of some sort?

I did note one Freestyle owner mention a coil going bad early, but honestly I don't think there are many high-mile Freestyles out there to get a good read on whether or not these things start failing @ 100K.

 

[ForestGrump]

lol. ford sold maybe 30 of them. Very true. I don't know when the last time I saw a Freestyle is.

Speaking of inspecting them, I did try to compare the coils with a multimeter (continuity/resistence) etc. No idea what I was doing and just gave up on finding the difference.

As for the COP failing, I've seen some theories:
1. Moisture kills them.
2. Heat/heat cycling kills them.
3. You drove on worn/improperly gapped spark plugs too long and it overloaded the coils (maybe that's what killed mine!)
4. I can't remember. (memory has been going bad since I was ~12)

If you're that afraid of infant mortality on the new COP, I would put them on the front first and drive around for a week. No misfire, no CEL then unbolt the manifold and move them to the back.

 

[JohnBrowning]

When it comes to OEM style coil on plug coils Ihave had good results with NAPA's brand. I know they used to be made in the USA but I am not sure if they still are. On top of that most of their Toyota parts for instance are geniune Denso parts often marked Toyota onthe part butin a NAPA box for a fraction of the price Toyota wants for the same part!

 

[JOD]

Thanks for all of the responses. I'm leaning towards buying some coils to have on hand, then inspect the old ones, testing them--then re-installing the old ones if I can get readings on them. Then, maybe on the next plug change a couple of years down the road, I'll have some new coils to put in at 120K. If they don't look good, I'll have some coils on hand now.

So, on to the next part. What coils? There's a guy selling a set of 6 'Genuine Motorcraft' (allegedly) coils on fleabay for $160.00. The same seller is selling 'aftermarket' coils for $100.00. Of course, these could come out of the same factory and I'm paying $60.00 for some stickers. They both could be fine--or junk.

OTOH, the NAPA coils look to be about $100.00 a pop. The Motorcraft coils from the dealer are around $100.00 as well.

Last option, I could check out some fancy-fly 'performance' after-market coils from one of the many Ford Freestyle tuning places out there. Oh, wait...scratch that....

Decisions, decisions..

 

[ForestGrump]

I would avoid aftermarket/fleabay coils. Aftermarket "performance" because you just don't know its quality. Fleabay because there are too many fakes and I wouldn't trust a critical component as coils to save a few bucks. Maybe blinker fluid, but not ignition coils.

What if the bad coils may leave you stranded? but you should be OK because you can make it home on 3 cylinders (disclaimer DO NOT ATTEMPT).

As for NAPA or stealer? Do you have an extended warranty etc? If yes then Stealer. that way they can't say you bought [censored] parts. Otherwise, whatever is more convenient.

 

[tom slick]

I wouldn't replace them but Rock Auto has 4 name brand listings at $65-70 including motorcraft.

 

[mechtech2]

If you can get a set of Motorcraft coils for $70, go ahead and buy them. Use them now or in the future.
A coil may test OK with an Ohm Meter, but it may leak in other ways.

 

[JOD]

Originally Posted By: mechtech2
If you can get a set of Motorcraft coils for $70, go ahead and buy them. Use them now or in the future.
A coil may test OK with an Ohm Meter, but it may leak in other ways.


Well, that $70.00 is for each coil--so we're talking about almost $500.00 just in coils. That's one of the reasons the $160.00 'genuine Motorcraft' coils on fleabay are appealing, and why I'm questioning changing them out when they're working fine.

I guess the last thing I'm wondering is if there's a potential issue changing just the (hard to reach) rears. I'm wondering if the resistance needs to be somewhat matched among all of the coils?

 

[ForestGrump]

I have no issues on the MPV with 3 new ones under the manifold and 3 old ones up front.

 

[JOD]

Originally Posted By: ForestGrump
I have no issues on the MPV with 3 new ones under the manifold and 3 old ones up front.


OK, that's good to know. Thanks!

 

[tom slick]

Unless these coils have a history of failing, the chances of having a defective coil are just as great as one of your current coils failing. New components don't equal higher reliability.

 

[Vikas]

I am not a native English speaker, can somebody explain me the usage of the word "prophylactic" in this context? I thought he was talking about how not get the coils wet

I actually did buy an extra coil after one of the coil died on the road on my 99 Honda Odyssey minivan. I am keeping the new spare coil, and hex-key needed to replace it, in the van. On Odyssey forum, many people have lost a coil but have not come across anybody who have lost more than one so far. Even the parts store stock only one or two.

- Vikas

 

[mechtech2]

$70 each?
I'd pass.
Coils normally last a long time.
Unless your car is known for eating them [usually from a lot of heat] , or has substandard types from the factory, leave the old ones in there. Clean them really well and use boot grease where needed, and to protect the electrical connections.