RS6 C5 Coil pack question

[chimjim]

Afternoon all,
I am quite new to the RS6 owners club having chopped in my S4 for one. I have a intermittent misfire, usually when warm and travelling, ahem, at speed. The engine also feels lumpier than normal. I am hoping it is the coil packs and I'm looking to change. The car has been revo'd and a knowledgeable friend suggested ditching the stock coil packs for Beru ones. Does anyone have an opinion on this and even a part number for them? The stock ones are 2-bolt type and all the Beru ones seem push on, would they still fit?? Are there any better options??
Thanks in advance!

[Dr G]

I'd have someone interrogate ECU for codes before shelling out on 8 coils. If it is indeed a failed/failing pack it will log a fault.

[chimjim]

Thanks for the reply, I scanned it and it came up with cylinder 1 & 2 misfire detected and also multiple cylinder misfire detected. The car has done 65k miles and there is no record of them being changed at all.

[k20erham]

99% will want the inlet decoking too I had one coil pack that went intermittent on my S8 V10 changed that and was fine still got random misfires that was the dreaded FSI coking, did it my self the coke was horrendous!!

[chimjim]

Doh! Thought that may be an issue... Any pointers on de-coking? is it straight forward enough?
ta

[k20erham]

It's involved lets say, but doable if your handy with the spanners, I'm sure there is going to be a really good market for a guy going around and doing this for those that don't have the Audi warranty and don't fancy spending £1500.00 with an independent to put right something that is actually a design fault and going to plaque FSI engines for ever.

[chimjim]

Well, I've got a spanner! Might do some phoning round....
Do you think its worth checking/changing the coil packs?

[Adrian E]

Assuming it's the 4.2 C5 it won't suffer FSI related coking, as it's not FSI

If you want to rule out coil packs, clear the codes and swap the suspect coil packs with cylinders that aren't reporting a problem and see if the problem moves too. If it does, great. if it doesn't the problem is elsewhere.

Coil packs were changed on a recall by Audi on cars of this era - our 2004 A6 had them done FOC when I spoke to my local dealer. They have it in and check if any are dodgy based on part number and replace any that haven't previously been done. If you can see part numbers on the tops of the coil packs compare all you have and you'll see if some have been done before. If they're all the same part number then they're either all original, or all replaced and should be fine.

[chimjim]

Thanks Adrian E, It is the 4.2. I know its bad but I wasn't sure if the C5 had issues with coking. I'll definitely give my local dealer a call and see if the car qualifies for the recall. That would be great!

[chimjim]

Turns out the screw in type weren't affected by the recall.... Are there any coil packs recommended for the C5 4.2 with a remap?

[Dr G]

I'd be tempted to go genuine as they have a 2 year parts warranty.

Carbon build up is an issue that can affect (almost) any direct injection petrol engine.

[daniel1920]

Swap coil pack from cylinder 1 & 2, do a couple of miles then scan for faults again, has the misfire changed with the coil packs?

Also does it misfire at idle? If so you should be able to hear a difference in running if a different clynider misfires.

Do you have an EML on? (maybe a bit of TL;DR)
Had a misfire problem myself on an Audi, the list of potential things to rule out is a joke, but you can get pretty far with checks yourself before talking to a garage

[chimjim]

I'll have a good look over the weekend. I cleared the faults yesterday and there aren't any there this morning. As I said, the faults seem to log after driving 'aggresively'. It also isn't as smooth on idle as it was. My thoughts were 1 or 2 coil packs were on there way out and when hot were struggling?

[daniel1920]

chimjim said:

I'll have a good look over the weekend. I cleared the faults yesterday and there aren't any there this morning. As I said, the faults seem to log after driving 'aggresively'. It also isn't as smooth on idle as it was. My thoughts were 1 or 2 coil packs were on there way out and when hot were struggling?

Ok, I guess heat would affect them. Also, its 2 cylinders, according to the codes anyway, should rule out MAF and O2 sensors, manifold and chain issues as they would tend to affect a full bank of cylinders at once

[chimjim]

that was my thoughts Daniel, also forgot to mention a slight smell of petrol when running! There are no obvious leaks under the bonnet. Like i said, it only really starts missing when, ahem, making good progress.....

[chimjim]

It was the injectors! 2 off needed. Thanks to Quattro tech in St Ives for sorting it out!!

[Adrian E]

chimjim said:

It was the injectors! 2 off needed. Thanks to Quattro tech in St Ives for sorting it out!!

Good stuff - that or a mapping related issue were potentials in the absence of coil pack problems.

They can be refurbished usually - they can spray test them and ultrasonically clean the nozzles. If a couple were bad it's one of those 'should I do them all' type jobs where the cost isn't small, unfortunately....not aware of it being a common problem although DrG will have seen many RS6s over the years!

[chimjim]

Well, it was fixed. Running great then, after a boot full on the way to Le Mans, missing! Checked and 'missfire on cylinder 4' was now coming up. Have asked the garage to order another 1. TBH, they are £129 each so thought its easier to replace rather than re-furb. Hopefully that will be it for a while...
I can't see if it is on a different cylinder now that it could be mapping related????

[Adrian E]

By mapping related, I meant if the injectors weren't found to be the cause.

If you've got a Bosch service centre near you ring them for a price on a refurb. Sounds like they could all do with checking over. If you're now up to 3 you're going to continue to have poor running issues, and the worry for me would be a poor spray pattern even if they're not throwing fault codes.