Change the Coils… not always the answer

[2006Lincoln]

I’ve read some very interesting and detailed posts that covered in great detail, the most common failure of the Lincoln LS: Coils. My thread asks the question: Has anyone actually researched and tested for the root cause for these extremely common coil failures?
Most will say… just change all the coils and spark plugs together, not individually as they fail. Check for oil contamination from a leaking gasket or vacuum leaks. Some of which, are the culprit, and fix the issue. But, what if you have no oil leaks or vacuum related problems? You’ve changed all coils, spark plugs and injectors. You’ve checked ECM pulse with a noid light, resistances with a multimeter, fuel rail pressures and bleed down tests, but still experience misfire, especially when the engine reaches operating temperature?
I’ve discovered the true root cause of this issue: Engine design.
One thing that is overlooked in every thread I’ve read so far… how heat affects wiring resistance. For every 1 degree Celsius, copper wire resistance will increase 0.4% (obviously dependant on gauge). But, what gauge wiring runs to the coils/injectors on the Lincoln LS? Approximately 18ga. This smaller wire, combined with engine heat trapped under the “coil cover plate”, ultimately leads to heat-sinking and drastically increases the wires’ resistance. Thus, creating a domino effect that destroys components like the coils and injectors.
The very design of the 3.9litre coil wiring harness is at fault.

 

[Buckie]

I’ve read some very interesting and detailed posts that covered in great detail, the most common failure of the Lincoln LS: Coils. My thread asks the question: Has anyone actually researched and tested for the root cause for these extremely common coil failures?
Most will say… just change all the coils and spark plugs together, not individually as they fail. Check for oil contamination from a leaking gasket or vacuum leaks. Some of which, are the culprit, and fix the issue. But, what if you have no oil leaks or vacuum related problems? You’ve changed all coils, spark plugs and injectors. You’ve checked ECM pulse with a noid light, resistances with a multimeter, fuel rail pressures and bleed down tests, but still experience misfire, especially when the engine reaches operating temperature?
I’ve discovered the true root cause of this issue: Engine design.
One thing that is overlooked in every thread I’ve read so far… how heat affects wiring resistance. For every 1 degree Celsius, copper wire resistance will increase 0.4% (obviously dependant on gauge). But, what gauge wiring runs to the coils/injectors on the Lincoln LS? Approximately 18ga. This smaller wire, combined with engine heat trapped under the “coil cover plate”, ultimately leads to heat-sinking and drastically increases the wires’ resistance. Thus, creating a domino effect that destroys components like the coils and injectors.
The very design of the 3.9litre coil wiring harness is at fault.

I love this comment! Personaly i don't like just throwing parts and money at something unless i know exactly whats wrong and causing my issues, that way when i fix it im not just guessing and maybe i can come up with a way to keep it from happening again.

 

[SteveOwens]

Go invest in a Fluke infra-red thermometer and point it at the exhaust manifold covers when fully warmed up. I'll find those two locations are the hottest parts in the engine bay. The manifold covers have one mica sheet sandwiched by two aluminum shells that are to shield the heat method. That heat from the manifold covers affect the engine mounts & wiring harness covers and connectors. The hydrualic engine mounts have a rubber construction & a white rubber umbrella heat shield to protect the top cone profile of the mount. The exhaust system heat is destructive to plastic and rubber parts that are near in the LS tight engine bay. Also the metal structural frame parts may distort dimensionally.
As for the coils failing due excessive heat, the coill covers hold the heat in when ran pass full engine warmup. Engine soak heat, spark plug heat through the boot & spring wire, and coil operating heat dissipation are acceptable when new. But with age that mica sheet wears and the manifolds begin over heat the engine bay. The way the manifolds over heat is by conduction & radiation. The air is heated below the valve covers plus the exhaust manifolds gaskets are stamped stainless steel units which conduct hot exhaust heat back into the cylinder head face. Heating the aluminum head throughly reaching the coils. This excessive heat first hardens the valve cover gasket material then the spark plug hole o-rings and then hardening the coil wiring sections.
As a temporary electrical coil fix due to the heat, I would use DeOxit D5 deoxidation spray on the connectors followed up with silver paste applied to the connector pins & socket, boot spring end to enhance electrical current flow.
( What are the three best conducting elements ? - Google search )
This analysis is what I found when I performed a complete exhaust system insulation job from the cyl heads face to the back of the mufflers. I can say this approach worked but helped me learn other conditions not revealed before.
If you desire what i did for the insulation job in detail I can re-post it with greater detail.

 

[Buckie]

Go invest in a Fluke infra-red thermometer and point it at the exhaust manifold covers when fully warmed up. I'll find those two locations are the hottest parts in the engine bay. The manifold covers have one mica sheet sandwiched by two aluminum shells that are to shield the heat method. That heat from the manifold covers affect the engine mounts & wiring harness covers and connectors. The hydrualic engine mounts have a rubber construction & a white rubber umbrella heat shield to protect the top cone profile of the mount. The exhaust system heat is destructive to plastic and rubber parts that are near in the LS tight engine bay. Also the metal structural frame parts may distort dimensionally.
As for the coils failing due excessive heat, the coill covers hold the heat in when ran pass full engine warmup. Engine soak heat, spark plug heat through the boot & spring wire, and coil operating heat dissipation are acceptable when new. But with age that mica sheet wears and the manifolds begin over heat the engine bay. The way the manifolds over heat is by conduction & radiation. The air is heated below the valve covers plus the exhaust manifolds gaskets are stamped stainless steel units which conduct hot exhaust heat back into the cylinder head face. Heating the aluminum head throughly reaching the coils. This excessive heat first hardens the valve cover gasket material then the spark plug hole o-rings and then hardening the coil wiring sections.
As a temporary electrical coil fix due to the heat, I would use DeOxit D5 deoxidation spray on the connectors followed up with silver paste applied to the connector pins & socket, boot spring end to enhance electrical current flow.
( What are the three best conducting elements ? - Google search )
This analysis is what I found when I performed a complete exhaust system insulation job from the cyl heads face to the back of the mufflers. I can say this approach worked but helped me learn other conditions not revealed before.
If you desire what i did for the insulation job in detail I can re-post it with greater detail.

All that heat build-up you are talking about is the reason i put a toggle switch on the black/white wire running to my LS's fan so i can keep maximum air flowing through my engine bay at all times. I believe that running my fan at high speed and a couple of other minor things i have done is why i haven't had much trouble out of anything under my hood. The only cooling system parts i have ever had to replace was a water pump a bad thermostat and the thermostat housing piece that holds the thermostat because one of the little ears broke off. Everything else is OEM and never been replaced even the degas bottle is the one that came from the factory.

 

[SteveOwens]

I'm glad you had good service from the plastic cooling parts and improvising an override fan swirch. The thermostat retaining ear can be reinforced with a countersunk 4-40 screws which seal fine with a #42 drill. As for the plastic cooling parts they're all 6061 aluminum now. When the mystery leaks start look under the engine, the middle engine leak is most likely the hot coolant feed from the from v of the block and around driver side rear fendor may be the de-gas tank.

 

[RADSLS05]

Tell me where to get an aluminum thermostat housing for 2005 LS with the 3.9l engine

 

[RADSLS05]

I love the look of the covers over the ignition coils, but I think they trap heat causing the failures. last summer I decided to drill several 3/16" holes along the sides of the covers were they are not seen. Don't know yet if it will work, but worth the try.

 

[SteveOwens]

Tell me where to get an aluminum thermostat housing for 2005 LS with the 3.9l engine

Call Peter at (613)4838186

 

[2006Lincoln]

All that heat build-up you are talking about is the reason i put a toggle switch on the black/white wire running to my LS's fan so i can keep maximum air flowing through my engine bay at all times. I believe that running my fan at high speed and a couple of other minor things i have done is why i haven't had much trouble out of anything under my hood. The only cooling system parts i have ever had to replace was a water pump a bad thermostat and the thermostat housing piece that holds the thermostat because one of the little ears broke off. Everything else is OEM and never been replaced even the degas bottle is the one that came from the factory.

Buckie, I think you may be on to a type of cure for dissipating the heat buildup. How exactly did you wire in a manual fan toggle switch? Any issues while using the A/C and the high pressure switch cut out?
My own attempts went a different route, where testing wiring resistances from the ECM plug (passenger side firewall) to coil and injector connections, I found them to be well above specs for length and gauge of wire. I chose to re-pin both connections, run new wire and replace connectors on both coil and injector ends. I used thermal sleeve over the wire loom and left the “pretty”coil cover plates off. I completely removed the plastic skid plate under the engine, in hopes to allow cooler air to enter the engine bay. So far, the car runs great… but I do try to avoid long idling in hot weather.
This engine bay is simply too restrictive for adequate airflow and as one post commented, is destroying more than just wiring.
Your idea may just be the solution to avoid endless repairs. Please keep us updated and pictures of your manual fan switch install would be great!

 

[SteveOwens]

Any photos of the re-wiring the coils & injectors ?

 

[04_Sport_LS]

for the coils failing due excessive heat, the coill covers hold the heat in when ran pass full engine warmup.

That's not true. I have a good DVM that has a lead that measures temps. I tried coil covers on... and coil covers off. The difference was negligible.

 

[04_Sport_LS]

That's not true. I have a good DVM that has a lead that measures temps. I tried coil covers on... and coil covers off. The difference was negligible.

That test was done over a decade ago.

 

[Buckie]

Buckie, I think you may be on to a type of cure for dissipating the heat buildup. How exactly did you wire in a manual fan toggle switch? Any issues while using the A/C and the high pressure switch cut out?
My own attempts went a different route, where testing wiring resistances from the ECM plug (passenger side firewall) to coil and injector connections, I found them to be well above specs for length and gauge of wire. I chose to re-pin both connections, run new wire and replace connectors on both coil and injector ends. I used thermal sleeve over the wire loom and left the “pretty”coil cover plates off. I completely removed the plastic skid plate under the engine, in hopes to allow cooler air to enter the engine bay. So far, the car runs great… but I do try to avoid long idling in hot weather.
This engine bay is simply too restrictive for adequate airflow and as one post commented, is destroying more than just wiring.
Your idea may just be the solution to avoid endless repairs. Please keep us updated and pictures of your manual fan switch install would be great!

Hey man i apologize for the late response. I dont get notifications right away. I will post some pictures later today of how i have my LS fan switch wired up. I agree 100% with pulling anything off that will allow that engine to run cooler. Coil covers,engine cover,plastic skid plate all act as a oven. If you live where its real cold all the time then it makes sense to keep them on so the engine reaches optimal operating temperature quicker. And No i haven't had any problems out of my AC or Heat or anything. It runs like a champ!! The only negative thing about having you're fan running all the time is its loud sounds almost like a jet turbine lol i like it. It sounds pretty cool to me. I will post those pictures for you after work today.

 

[Buckie]

Buckie, I think you may be on to a type of cure for dissipating the heat buildup. How exactly did you wire in a manual fan toggle switch? Any issues while using the A/C and the high pressure switch cut out?
My own attempts went a different route, where testing wiring resistances from the ECM plug (passenger side firewall) to coil and injector connections, I found them to be well above specs for length and gauge of wire. I chose to re-pin both connections, run new wire and replace connectors on both coil and injector ends. I used thermal sleeve over the wire loom and left the “pretty”coil cover plates off. I completely removed the plastic skid plate under the engine, in hopes to allow cooler air to enter the engine bay. So far, the car runs great… but I do try to avoid long idling in hot weather.
This engine bay is simply too restrictive for adequate airflow and as one post commented, is destroying more than just wiring.
Your idea may just be the solution to avoid endless repairs. Please keep us updated and pictures of your manual fan switch install would be great!

Alright sorry its late but i work all day then come home and work on my Aerostar Van that im restoring. Heres the pics i promised. I pulled the toggle switch off to show you exactly which wire i cut and hooked the toggle switch into. You can see in the picture where i put the black n white wire back together. If you need a picture of the toggle switch hooked up i can post that for you as well.

 

[SteveOwens]

Thanks!

 

[04_Sport_LS]

Tell me where to get an aluminum thermostat housing for 2005 LS with the 3.9l engine

Won't work. 2005 is gen 2. Gen 1 housing is completly different.

 

[RADSLS05]

Thanks!

I didn't call Peter, I already had done quite a bit of research and was pretty sure that the only thermostat housing for the gen 2 was plastic, but I sent out the post just in case I had missed something.
I might be wasting my money on a 20 year old car, but my LS Ultimate has every option available in 2005. I picked it up in 2008 for 20K with only 9K miles on it. Some guy in Arizona never drove it so the battery kept going dead. He complained so much that Ford bought it back from him and it ended up at a dealer here in Minnesota. I baby it too much, It gets stored for the winter so it doesn't get the the crap salt they put on the roads here in Minnesota. The only upgrade I plan to do is replace the the fantastic sounding factory Pioneer THX/navigation receiver with a Kenwood that has all the new bells and whistles. With a lot of patch rewiring required to keep the 2 power amps, I'm just going to replace them with new ones.