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branouxx Netherlands

Wed Feb 28 2018, 12:49pm

Joined: Nov 12 2017

Member No: #3334

Location: amstelveen

Hallo,
Since september 2017 I'm the happy owner of a C6 3.0 exclusive petrol and recently I had a problem with a coil (or bobbin or spool, I'm Dutch so not sure what's the right word:).
The (official and reliable Citroendealer) service station told me that this could have been caused bij poor petrol quality (budget 95). They advised me to use only 98 or 102 petrol quality.
Does anyone have an opinion on this subject? Thanks for a reaction.
Best regards Luke

ps I had them replace all the coils, all of them about 10000 miles old.

markp

Tue Jul 10 2018, 03:51pm

Joined: Jun 10 2014

Member No: #1746

Location: Somerset

Sorry for the late reply.

Yesterday I replaced the second coil on my 3.0 petrol C6 since I took ownership at 35,000 miles. This is at 62,000 miles. Looking at the coils I would say that it is very certain that none were replaced before I owned the car.

The first failure was on the rear bank under the inlet manifold. The second (yesterday) was on the front bank and happened on a *very* hot day (for the UK) - 29C.

Petrol quality should make no difference at all (I mainly use LPG and it uses a little 95 Octane). All that a coil does is "step up" the voltage going to the spark plugs from 12 volts to over 12,000 volts. The petrol quality shouldn't affect the resistance of the air/fuel mixture across the two spark plug electrodes and therefore shouldn't affect the current drawn - a higher current drawn would potentially make the coil hotter and cause it to fail.

Heat is what kills coils (hence mine failing on a very hot day). Clearly coils can last a long time.

If your first failure was, for example, at 50k miles, then replacing all of them *may* make it more likely that you will get a failure, as it may introduce a poorly made coil, which your existing coils have proved themselves not to be by making it to 50k miles.

What really confused me, when I replaced the coil, was the cylinder numbering system used on the car! Imagine standing in front of your petrol Citroen C6, with the bonnet open, looking down at the engine, with the belts and pulleys at the left end of the engine and the gearbox at the right. The order is, as you look down (rear bank is the first line of numbers, front bank second - closer to you):
6 5 4
3 2 1
which is utterly bizarre!
So 6 5 4 are hidden under the inlet manifold.
3 2 1 are easily accessible under the clip on plastic engine cover.

I got this numbering from here (and it matched my Lexia diagnosis):
- Click Here -
(which is confusingly written) and here (from Thug Pug's comment):
- Click Here -

Cheers,

Mark

arconell3 Germany

Tue Jul 10 2018, 06:09pm

Joined: Jun 28 2012

Member No: #922

Location: Kalkar

Hi Luke,
The failure of the ignition coils have nothing to do with fuel quality. The reason is that they get very hot because of their position right on top of the spark plugs. It is something all 3.0 V6 owners will have to live with. Best to have one or two spares ones on board. No need to replace coils that are still functioning, you never know in advance when they reach their Waterloo, sooner or later they all do. Most owners say they last anywhere up to around 60.000 Kms. Since you are Dutch, you may want to read these pages: - Click Here -

Regards, fijne avond,
Robert


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