Coil 2 Answer 0

Last Saturday my car developed a sudden misfire @ 3000rpm. At first opportunity (1/2 mile) I stopped, switched the engine off, & checked the plug leads. Set off again & misfire still there, & after a further 300 yards engine died. To my horror, the coil pack had literally statrted to melt, with “stalactites” of melted plastic on its underside

Fortunately I was only a couple of hundred yards from LRV (where I was headed), so with a bit of help the car was pushed to their workshop.

New coil pack arrived yesterday, & LRV fitted it late afternoon. BUT it wouldn’t start, & it would be checked out today. So, at around 3.30pm this afternoon I pop up to LRV to see how they’re doing - technician had just recommenced work on the car, so I join him in the workshop. He finds a dodgy fuse, replaces it, & the car starts, but only firing on 3 cylinders. Diagnostic tool reveals fault on fuel injector, cylinder 3. Engine is switched off, & diagnostic tool reset. Engine fired up again, but is still running on 3 cylinders - for next 2 minutes, technician studies the diagnostic tool whilst sitting in the car. All of a sudden I see smoke coming out of the coil pack Engine is immediately switched off, & head scratching mode invoked!

It’s now just after 4pm, nowt I can do except leave them to check the wiring etc tomorrow & hopefully find/cure the fault!

Any pointers from our resident experts, apart from perhaps a dodgy ECU, or faulty wiring to No 3 injector?

Anyway, whilst I was there I had a poke around in the yellow S2 Exige thay had just taken delivery of. Looked a damn sight better looking than the black one at Donington recently. Nice road car etc, etc, etc, but it really is just an Elise Coupe.

Fingers crossed.


Have they checked the plugs ?


Yeah, the plugs were out when I got there - nice & clean & the gaps were checked before refitting.

I’m hoping that it’s something simple - but it’s so damn time consuming isolating it!


If the coil goes into meltdown as you describe I’d conjecture (at this stage) that it is nothing to do with the LT side of the house ??

Therefore it would have to be the HT so… … given that you have replaced the coil and the problem still exists - and infact cost you another coil - its gotta be something to do with leads and or plugs… so i’d remove your magnecors… borrow or buy some new standard leads (infact you prolly still have some ehh ??), replace the plugs with new ones regardless of how good the current ones look and replace your coil again !!

I’d then make sure the plugs get torqued to 25Nm, check all the fuses and fire him up… wait a few minutes and see what happens…

I think the #3 injector is a red herring for the coil meltdown problem anyway… i mean how could a faulty injector do this??

If the coil feeds into an open circuit or an incorrectly earthed plug then the stored energy would have to be dissipated somewhere… it would discharge within the body of the coilpack…this would heat the coilpack up… I don’t know the numbers but we could be talking lots n lots of Kilojoules here, and thinking about it this is the only place i can imagine that would generate enough heat to melt the bleeding thing down yeh ??

keep us in th eloop. and awerabest

BTW what fuse was it that blew??


Excellent point, well made I have relayed your thoughts to LRV, who hopefully will be able to continue work on the car this afternoon - that bloody S2 Exige is being PDI’d this morning!!!

I believe it was the coil pack fuse (left hand one in bulkhead/ECU compartment), which was really to be expected.

Thanks for your input.

Rob hope the experts get it sorted pdq, don’t want you to b looking over that new Elise Coupe too much

Rox I reckon that’s a superb bit of diagnosis - am well impressed - reckon you should b charging LRV consultancy fees if turns out to be cause

Bad news mate, hope you get it sorted asap. Don’t you go letting that new coupe thing (that even my wife would like to drive) distract you. After all you’d have to re-jig the sunstrips and everything

I can assure you that the new coupe has zilch appeal for me. I quite like the looks of the Elise 111R & can understand it’s market placement, but the coupe…nah, not at all.

I can assure you that the new coupe has zilch appeal for me. I quite like the looks of the Elise 111R & can understand it’s market placement, but the coupe…nah, not at all.

LRV have not had chance to do anything to my beloved today, cos they have the official opening of their Manchester showroom (literally a shop window!!!) this Saturday & Sunday. I shall be on their backs on Mondsay to get the damn sorted within 48 hours

Just had the phone call I was waiting for

Apparantly a wire had chaffed as it passed through the bulkhead from the ECU, & was shorting.

Setting off now to go & collect my little beaut - pity it’s crap weather compared to yesterday, Oop North.

Hey, congrats!

How long did it take them to find it?


Hey, congrats!

How long did it take them to find it?


Cheers, mate.

Total time charge was 4.5 hours, coil pack (1 only!!!) was �95 - all plus VAT of course

At least all’s well again, & the smile driving the 20 odd miles home helped ease the financial pain.

Glad it’s all sorted…Suppose it could of been worse financially

great news Rob, glad to hear it’s all sorted

Thanks for the support chaps - much appreciated

What is it about these cars which gets us all excited Only kidding

Rob, glad it wasn’t too major…but concerned that there was a chaffing wire through the bulkhead - was a grommet or some other form of protection missing off yours because if not then we could all be next…


Sorry, don’t know the answer to your question, but I do know that the wires are now well protected by a sleeve made from some old rubber hosing.

It is probably a good idea for everyone to check their’s out, & add some extra protection (cue Uncle Mike!). I reckon it was probably a result of transverse engine “rocking”, even though I’ve got nylatron engine bushes which considerably reduce it.

PS I’ve some “Elvington specials” (cheap as chips)waiting for your collection - so give me a ring - are you coming to the Watermillock on Weds 5th May?

Bang goes another of my theories…

Glad you got this fixed Pesky… so it was the low-tension side of the coilpack… by the sound of it? I wonder exactly what was happening… did they give any explanation.


Your theory was taken seriously (once again, thanks) - all the plug leads were checked (& a different set used for testing) - but the misfire continued.

The wire through the bulkhead was shorting, which was cocking up the signal to the coil. As usual, I didn’t ask for a technical de-brief of the resultant problem, cos I wouldn’t understand it anyway! I was just happy/relieved that they’d found the cause & it was something simple - I was dreading being told I’d have to fork out for a new ECU! Obviously, if I had needed an ECU I would have wanted an Emerald (plus verniers), so the logistics of going down that route with the dealer would have been interesting - I think!

The lads at LRV did a good job given the nature of the problem, & the fact that their workshop is extremely busy at the present time

Cheers Pesky

another one for the encyclopedia