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My 06 had been idling rough and throwing all sorts of misfire codes earlier this year after having no problems during the previous year and a half of ownership. I had seen several posts about bad coils with accompanying pictures. I looked at my coil packs on several occasions and they never looked that bad. No sludge, no rust, no moisture, no powdery residue. There were a few brownish/black spots, but it just looked like where the plastic shaft had become discolored due to the heat. I tried all sorts of things to try to fix the problem, but eventually took it to a dealer for treatment.

One of the dealer's mechanics pulled the coils and said they looked okay and moved on to other possible causes. Several hours later, the service manager recommended checking the coils again after talking to the Lotus rep on the phone. Upon closer inspection, the small black/brown spots were definitely burn marks and pitting where there had been arcing and intense heat.

After replacing all 4 coils, the car was like new. Since the coil failures were so gradual, I hadn't even noticed the extent to which the car's performance had suffered. Still not sure why all 4 coils had some degree of arcing after only 12,000 miles. The car is garage-kept, rarely driven in the rain, and I take care to cover the engine during washing.

For anyone else's benefit, below are some pics of one of my coils. The first is the coil itself. Looks pretty good, right?

Coil-Entire.jpg

The second shot is of the "primary" arc point near the top of the coil. I have removed the rubber O-ring around the top for better visibility.

Coil-Top.jpg

The third photo is of a very small arc point near the bottom of the coil shaft before it starts to taper down. I point this out because on each of my coils there was a top arc mark and a corresponding lower (but smaller) arc mark. (Electrical entry and exit points?).

Coil-Bottom.jpg

The last photo shows these two points in one photo. The top and bottom arc points were always close in a line with each other.

Coil (2 points).jpg

As mentioned above, after replacing the coils, my P1301, P1302, P0300, P0301, P0302, P0303 and P0304 codes virtually disappeared. If anyone has been having misfire problems and their cams and rockers look okay, it may be a good idea to look at your coils closely. This taught me that the coils don't have to look horrible to be failing.
 

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My coils look like that. i posted about it way back. I never did get replacements. What did the replacement parts cost? Maybe I'll just replace all 4 with a fresh set and call it part of my 50k mile maintenance.

-doma
 

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Discussion Starter #3
My coils look like that. i posted about it way back. I never did get replacements. What did the replacement parts cost?
-doma
I thought I had read all the posts on arcing, but must have missed yours.

The dealer (3 hours away) only had 2 replacement coils in stock when I was there, but they were covered under what was left of my warranty. I picked up the other two at my own cost from the local Toyota dealer for about $125 apiece.
 

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a trick i learned from a guy who has been racing a long, long time to check for electrical problems is to run the car in the dark, and peek under the hood of the car to check for sparks/arcing.
he did this in a garage with a vent for a clothes dryer and used a venting tube connected to the tail pipe and routed out the vent hole. we dont all have this, so I would think that it could be done under other circumstances to reduce the lighted area around the car would work as well.
maybe even just a really dark night and try it.
seemed like a good way to check things out, and a good way to diagnose any issues with the car.
just sharing.
 

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It might be a good idea to cover your new coils with di-electric grease.
Yep. Mine were acting up, and that fixed it. Put plenty of grease in the spark plug socket of the coil. I used 3M silicone paste dielectric grease.
 

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I wonder if slipping a piece of silicone tubing over the upper part of the coil might help, too. Anybody know the outside diameter of that part of the coil (where the arc marks are above)?
 

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Di-Electric grease is about the only thing that will work. The coil to tube clearance is nill. I tried slipping thin shrink wrap over the coil a few years ago and it wouldn't fit back in the tube. Like I said, it's a very close fit...From what I gather, the problem has to do with ionization of the air around the coil making for a very conductive environment.... or something like that:shrug::eek:
Long and short of it is that a VERY healthy coating of di-elec grease around the coil and up in the plug boot tends to solve the problem:up: Make renewing the grease part of normal maintenance and the mis-fires should subside.

Best,

Phil
 

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OK Phil. I didn't realize the tube ID was that close, that may be part of the problem. Be nice if the tube was non-conductive...
 

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Discussion Starter #10
Di-Electric grease is about the only thing that will work. The coil to tube clearance is nill.
+1

I first tried wrapping electrical tape around the shaft as a short-term fix for the old ones, but the tolerance is so tight, I could barely get one layer of tape on. I went the di-electric grease route on the new coils and slathered everything up good. (Okay, no jokes about greasing my shaft).

I didn't think it was possible to re-use the old coils. I figured that if the arcing had already managed to "burn" through the heavy duty plastic on the shaft, what sort of protection would a 1/10 mm piece of insulation or layer of grease provide?
 

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Be nice if the tube was non-conductive...
You could disassemble the head and spray the tubes with an insulating paint or other compound, but there's not really any great need. Keep 'em slathered with di-electric and they're fine.

It's also not a bad idea to put a fine skim of silicone onto the rubber gaskets and attach them to the coil semi-permanently. Helps keep moisture out of the tube, which is a constant issue given the issue of the head, coil cover, and open engine lid. A LOT of water gets into the coil pack area in any kind of rain/washing/etc.
 

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About the grease: I've never bought 'dielectric grease' before. Can I actually walk into a kragans or napa and pick up a tube of dielectric grease? Or is it known by another name?
Any auto parts store will have it. It generally comes in a small pressurized can with a screw-on nozzle.
 

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OK. The 3M claims to be for dielectric use, but I'll try your stuff.

Description
3M™ Silicone Paste is a non-hardening, water resistant, 100% solids, silicone based compound
designed to lubricate, protect surfaces from oxidation and serve as a dielectric compound. It is a high
viscosity paste that will remain in place for a long period of time. It can be applied heavily to help seal out
contaminates and elements that lead to oxidation and corrosion or it can be spread out thin to leave
behind a virtually unnoticeable film. A brush is permanently attached to the can top to make applying it
more convenient.
 

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Thanks Guys!

I've owned my 2005 Elise since March 2009. Only 13k miles. It has always idled rough and lopey. Occasionally, when I would let off the accelerator quickly it would make a popping sound. Especially on the track at 8000 rpm. I couldn't make it do the sound when my Dad was in town (he builds stock cars.) So, I ignored it.

I had no idea what was wrong with my car until the engine light went on. It was a P1302. The guy at the auto parts store cleared it for me. Then I ran home to consult Lotus Talk... :D

I read this post then I pulled each coil and saw the exact same brown spots in the exact locations as your pictures above. I ran out to the auto parts store again...in the truck. I priced the new coils at $69 each, and bought the di-electric grease. I greased each one up really well. The difference is amazing. It idles perfectly and there's no popping sound ever. It's only been a couple days, I'll let you know how long this fix works on my old coils.
 

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Only just found this post.

Had a recent similar problem. Diagnosis was easy. Took out coil pack and while still connected rested it on the main engine block and started the car. If the insulation is damaged you'll see sparks coming out thru the rubber wall rather then just from the spark plug end, expecially if you rev the motor.

An autoelectriction told me you can coat it in any for of silastic, roofing, gaps etc and he's seen lots of cars that come in fixed as so. I was concerned about engine temps and the silastic or dielectric grease catching on fire so ended up just buying a new coil pack.

I also tried insulation tape but the sparks still went through it. Probably too much voltage?
 

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Only just found this post.

Had a recent similar problem. Diagnosis was easy. Took out coil pack and while still connected rested it on the main engine block and started the car. If the insulation is damaged you'll see sparks coming out thru the rubber wall rather then just from the spark plug end, expecially if you rev the motor.

An autoelectriction told me you can coat it in any for of silastic, roofing, gaps etc and he's seen lots of cars that come in fixed as so. I was concerned about engine temps and the silastic or dielectric grease catching on fire so ended up just buying a new coil pack.

I also tried insulation tape but the sparks still went through it. Probably too much voltage?
Silicone grease is good to much higher temps than motor oil, so if the head is getting hot enough to destroy silicone grease your engine is toast.
 
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