The funny thing connected to my coil

[lesliehedley]

Next to the coil on my 400SE is what looks like a large capacitor. One end is earthed and the other end goes to the -ve low tension connector on the coil. Is this for radio interference suppression or does it have an effect on how the car runs? My car has developed a hesitation or random misfire when the throtle is opened although it idles evenly. I was wondering if this item could affect the running or whether I might have a coil on its way out. The coil is a french make (Decellier I think). Has any one ever heard of them? Should I replace it with a Bosch one from ACT?

[lesliehedley]

Here's a picture if it works:

Edited by lesliehedley on Sunday 8th October 00:08

[Mr Jenks]

Ducellier are a French company and have been in the business a long time, supplying o.e. parts to many manufacturers.
It looks like a radio supressor fitted to your coil, it should however be fitted to the +ve side of the coil and not the -ve. I have seen coils which are correctly wired but marked up wrongly on the casing, causing all sorts of running problems. I would certainly change the coil for a genuine Bosch one.

[adam quantrill]

Doesn't the capacitor absorb some of the back EMF generated by the coil when it's fired (i.e. disconnected from the LT supply). In the old days this prevented arcing at the points but I suspect these days it is there to protect the ignition amplifier from the voltage spikes.

[dickymint]

Could try the bag of frozen peas on the coil trick.

[l33]

dickymint said:

Could try the bag of frozen peas on the coil trick.

WTF? - What does this do apart from gently simmer the peas?

[GreenV8S]

The capacitor used to generate the spark would be in parallel with the points rather than between coil +ve and ground. I would guess this one is something to do with RF supression.