faulty 2005 C5 V6 ignition coil...

[AlvinCitroenC5]

Hi, I have recently have issues with my 05 C5 V6 456 rear bank ignition coils. I have replaced the original Sagem (made in France) ones with Delphi (made in Portugal) ones and also changed the connectors. However, when the vehicle is driven hard, cylinder 4 still misfires. In addition, I scanned the engine fault code and checked the energized time of the coils: the Sagem that are still in the vehicle in bank 123 all average at 1.7ms, while 4 is faulty with a energize time of 1.9, 5, with 1.9, and 6 with 2.2. I have checked the plugs, power from alternator, and ground, all is well. Does someone have any idea as to why bank 4's coil is still having problems? And why bank 6, although working without a fault, as to why the energize time is so much slower than the rest? In your experience, are the Sagem coils better than the Delphi coils? Thanks.

[jamescarruthers]

Delphi are well regarded over at the Avantime owners forum where they share our 3.0 V6 engine; they recommend avoiding Sagem. So you’ve made the right choice at least!

Have you considered that the new coil may be at fault? It wouldn’t be unheard of. Maybe move it somewhere else and see if the fault follows. Not the nicest advice I know as the rear coils are surprisingly time consuming to get to.

Different car, same engine: when my Avantime had a misfire I changed all of the coils but it didn’t help. The culprit was a multi plug that was a bit dirty. I unplugged, cleaned it and reconnected and it drove perfectly after that. Maybe the C5 has a plug with the coil/ignition signals going through that would benefit from similar treatment?

[AlvinCitroenC5]

James,
On the last paragraph of your reply, you express that the bottom of the camshaft camber/case that meets the cylinder head can also leak, and state that applying sealant can solve the issue. Can you clarify if you have removed the chamber/case entirely to apply the sealant, which is quite a big job, or just cleaned the area and applied the sealant? Thank you.

[xantia_v6]

I think that you might be referring to my reply in your other topic about oil leaks. Yes, I removed the camshafts and the block they sit on. Not a small job, but not much more than a timing belt change.

[AlvinCitroenC5]

Yes. I was referring to my other post. Thank you.