Cover less.

andybuzz2u

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I have a 2004 LS 3.9L V8. Today I got a couple of miss fires. Is anyone running there LS without the coil covers? It just seems to me that there is way to much heat for any coil to survive closed in like that and I suspect that is what is killing them. I have already ditched the bulky engine cover.
 
Some people here are running without covers, and that seems to be okay.
The problem doesn't seem to be heat. They originally used the wrong epoxy. I think that some (many?) aftermarket coils still are using the wrong formula. The newer coils from Ford (as of a few years ago now) have better epoxy and seem to be lasting over 100K miles, with the covers on.
I doubt that they actually run any cooler without the covers. The coils are not designed for air cooling and the design of the coil wells doesn't encourage air to flow around the coils even without the covers. I haven't measured temperatures with and without the covers (bet no one else has either), so I could be wrong. I can say that good coils work just fine with the covers, and it gets and stays pretty hot here.
 
Who supplied the COP is the question. A lot of counterfeits on eBay and Amazon. I do know Ford issued a bulletin about counterfeit Morotcraft parts and bags. Myself, I do not work in Dearborn I work in Auburn Hills. Standard, Wells, and Bosch have always been our prime COP suppliers. The ignition coil primary windings failed in my nephews 3.9L #5 and #6 on the last two Motorcraft coils in the car. Now I have to replace all 8 COP's and the PCU. I would like to see some heat soak numbers on the COP's closed up and opened. Once the engine is shut off, even with the little electric coolant circulating pump, the heat soak from the heads has to be well over 250F. I am sure it gets hot.
 
I purchased my LS V8 with 75K miles and almost immediately started having coil problems. Put all new coils on the vehicle, (non-Motorcraft & non-Ebay), along with a plug change... and am now at 205K+ with no coil failures. I did do a coil boot change at roughly 180K when I did VCG's.

I do think that the covers trap heat from the cylinder head below, rather than letting it escape into ambient air. However,,, there is also another issue that will cause coil problems. There is a bulletin through Ford, about the wiper cowl seal failing, which allows water to dump onto the main coil harness going under the cover. The water migrates through the harness and causes coils to drop.

The only issue I have had with the covers off... was driving in a pouring rain on a section of road that didn't normally have standing water. When I hit the water, it was enough to drench the engine. The coils started mis firing, but dried off after a minute or two, (due to the engine heat boiling it off).

I'm not disputing anything else said here. Just offering my experience.

If someone has a VOM with a temp probe option, it wouldn't be too hard to check temps with one cover on, and one off. I'd do it but I'm so busy I'm lucky to keep up on oil changes at this point.
 
Thanks for the answers. Myself I would have kept them off, but my nephew overruled me and it is his car, he likes the engine with all that stuff on it.
 

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