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First of all hi all, im a new'ish owner of a c5 rs6 and after buying the car in October ive just started seeing a few issues with it. First of all a misfire on start up from cold. Its not noticeable that much whilst its on the enrichment but as soon as the revs drop off it starts to run rough. No eml and it seems to drive fine once its warm with no noticeable misfire under load. Im getting 4 fuel trim faults (2per bank) a misfire on cylinder 6 fault code and random multiple misfire code, so my plan was to start with some fresh plugs and maybe try a coil on cylinder 6.

I just wanted to ask your advice on if there is any preferential plugs to use in these motors?

Thanks
Matt

You need - NGK PFR7Q

FON and welcome along.

Most of the info you'll need while owning your C5 RS6 has been put into a guide by some rather helpful gents - viewtopic.php?f=2&t=15229

Have a read through there mate

Sounds like a vac leak. Unlikely to be plugs if you're getting trim issues, but probably worth changing anyway. You have to change them every 20k miles on the RS6. Have a search on here for vacuum leaks.

Could be fuel pressure related.

Post up your codes. Might help diagnose.

Also, FON.

I did my plugs recently as I had misfire UNDER load (which the plug change sorted). It also had a bit of a rough idle.

Also just to note, from my observations the EML flashes on the occasional missfires and then we stay on permanently once it has logged a sustained missfire.

It does sound like it something more like what Shopp suggested.

Im not getting the EML coming on just an annoying rough idle. It seems to pull well with no hesitation in terms of a misfire. I will have to get a smoke check on i too. Its only due to a misfire on cylinder 6 i thought i ould need to start with plugs and coils.

Just wanted to see what plugs people recommended so im not changing them twice.

Matt

Plugs are simple. ONLY NGK PFR7Q

On a turbo motor it's very important to have exactly the right plug.