Question about spark plugs and coils

[chrispwill]

Hi,

I have a N54 335i, which is misfiring on cylinder #3.

Reading online I should replace the spark plugs coils, and possibly injectors. I want to start with spark plugs and coils to see if this fixes the problem, but had a couple of questions:

1) Regarding a spark plug change, should I change all the spark plugs at the same time, even if just #3 is potentially faulty?
2) same question with the coils, or can I just change coil #3? If I can just change the one coil, does it have to be the same brand as the other coils present?

Thanks, apologies for potentially nooby questions, not done this before.

[Penelope Stopit]

You're jumping the gun
Swap plug and then coil if need be with a working cylinder and see if that cylinder now misfires and the no 3 is ok, you can do the same with the injector if you need to

[Krikkit]

Since it's coil on plug I'd swap the coil between two cylinders, see if your misfire moves. If so then you could replace them one at a time, but a set of 6 of the improved-design coils about £110 (Delphi), so why not do them all?

I'd be astounded if it's the plug, what's their age on the car? Generally plugs last a ridiculous amount of time.

[chrispwill]

Fair enough, that actually makes a lot of sense. I'll give that a go tonight.

Car is on 92k, 2006

[chrispwill]

Krikkit said:

Since it's coil on plug I'd swap the coil between two cylinders, see if your misfire moves. If so then you could replace them one at a time, but a set of 6 of the improved-design coils about £110 (Delphi), so why not do them all?

I'd be astounded if it's the plug, what's their age on the car? Generally plugs last a ridiculous amount of time.

In case I did need to replace coils, where did you find that pack? I can't seem to find it on google.

[Krikkit]

These were the ones I found, came through a BMW forum's guide on the best plugs/coils etc searching for Delphi GN10571.

https://www.cartech-one.co.uk/en/product/3650500-d...