Hi
My FiL's Scenic petrol (2002) has had 6 sets of coils replaced since new. What are coils, what is their function and why are Renault coils in particular so unreliable?
{Slight edit to subject header - DD}
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I don't believe they were any more troublesome than the VAG coil saga. Badly engineered batch, later ones were OK. Six sets seems a bit excessive.
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They are electric and they are Frnech and they are in a car! A triple whammy!
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cos they are a nice serviceable item after warranty time
you need 4 sir
a tip for doing a job so well?...........well thank you sir
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our friends at Wikipedia give the following definition:
'In modern systems, the distributor is omitted and ignition is instead electronically controlled. Much smaller coils are used with one coil for each spark plug or one coil serving two spark plugs (so two coils in a four-cylinder car). These coils may be remote-mounted or they may be placed on top of the spark plug (coil-on-plug or Direct Ignition). Where one coil serves two spark plugs (in two cylinders), it is through the "wasted spark" system. In this arrangement the coil generates two sparks per cycle to both the cylinders. The fuel in the cylinder that is nearing the end of its compression stroke is ignited, whereas the spark in its companion that is nearing the end of its exhaust stroke has no effect. The wasted spark system is more reliable than a single coil system with a distributor and cheaper than coil-on-plug.
Where the coils are remote mounted they may all be contained in a single moulded block with multiple high-tension terminals. This is commonly called a coil-pack.'
and see HJ's own write up on this car for the known issues.
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Fortunately I'm unfamiliar with Renaults, but as someone else has pointed out, there have been a history of coil pak failures on VaG petrol engined cars too with a bad manufacturing run from the factory. However from an engineering perspective, as in many cars the coil packs are mounted on the engine or very near/on top of the plugs themselves. I suspect that subjecting something relatively delicate such as a finely wound coil to these extremes of temp and vibration cannot be a good thing, as compared to the old style bulkhead mounted units which hardly ever used to fail.
Its interesting that someone mentioned the shared coil or wasted spark system, this is the way Harleys did their ignition and probably still do 50-60 years on.
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I have to take issue with " as compared to the old style bulkhead mounted units which hardly ever used to fail."
I know we tend to look back with rose tinted etc.. but I recall 2 coil failures - one Mini and iirc one a Mini...:-) I mean the original Mini....
But iirc most makers eg SAAB had coil problems..
Having said that Renault electrics are notorious for being carp and deservedly so ....
madf
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in the 'rose tinted' days I recall that placing a hand on the coil to check its temp was a common fault diagnosis technique. I had at least three coil failures, a 3l 'Sweeny' Granada, a Mk2 Escort and a Datsun 160J SSS - loved that car, dogleg 1st gear and all but it had the rustiest floorpan ever.
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I recall that placing a hand on the coil to check its temp was a common fault diagnosis technique
>>>>>>>>
>>>>>>>>>>>> and if wired the wrong way you could cook an egg on it,i always remember scare stories of them exploding but never seen one gone,i never got round to cutting one open either although i often thought about it to see how much oil was in them
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bb
I have seen a couple that have gone bang: nothing dramatic - but miles of fine wire to untangle from everywhere in the engine bay. [And one just had to be on a TK horsebox...!]
There's about a cupful of transformer oil inside; it contains PCB, so is very nasty stuff indeed.
Oh, and getting back to the OP's post. Scenic 16valve coils sit in deep wells directly under the scuttle lip and get flooded every time it rains - another example of brilliant French design!
Still; nice little earner.
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