C5 rs6 engine misfire

[james85]

Hi chaps
wondered what peoples thoughts are or if you had similar problem?

Was driving along the m1 felt a little bit of hesitation under acceleration , about 10 seconds after accelerated at about 50% throttle and then had a misfire , pulled over no smoke or anything . Oil and water look ok.

Ive checked the codes , I have cylinder 4 and cylinder 8 with misfire.


Is it looking like coil packs? injectors? hopefully nothing worse




thoughts
?



cheers


james

[Scotia]

Not to sure if it’s worth just checking before you go changing coil packs , check your external transfer fuel pump underneath the car as if this if this is on its way out it can throw up all sorts of fault codes . Had this fault recently had a few fault codes so changed Mafs but nothing ,so checked external fuel pump it’s underneath the car you can feel it when you lie down around rear passenger door area on driver side of the car . Have the car running and feel if the pump is running ok or noisey. Changed mine and fuel filter which sits next to this pump myself and car runs better than ever ,smooth power and throttle response better . Anyhow only an idea my friend.

[james85]

Yes could well be that just had a quick look and it does look as though it could have been leaking.
I was thinking could have also been some shitty fuel as I had filled up about 30 mins prior.

anyway hopefully nothing too major its going into the garage Friday

[james85]

Found out what it is. A spark plug has blown out and also knackered the coil .

Its all blown out so nothing has gone into the engine

not sure how that happened

[Shoppinit]

Holy <beep>. You dodged a bullet.

Rule 1.

[V!per]

Heard that before with Friends S6 - after replacing plugs to new ones. Sometimes they tend to unscrew and then get blowned out. Something to do with the gasket on them. Nied to screw it in tight , unscrew them and screw in again or better yet do that with a nut outside engine to get the gasket. Or after changing the plugs check them again after wa week or two and tighten them up a bit.

[james85]

The good news is she will live to fight another day.

The bad news is the thread where the spark plug screws in is damaged, so the head has got to come off which is quite a job.

[james85]

Back in business! Was certainly thinking the worst at one point.

The thread was sorted without taking the car to bits thankfully.

Got the coil packs changed and a full service and shes pulling like a train again.
Next job wheels need powder coating.

[Shoppinit]

How'd you sort the thread?

[Mɐʇʇ]

Also - about torquing plugs up - with new plugs I always use a torque wrench to make sure I get the right crush on the washer. TBH, even on used plugs I do tend to that these days, but if not, the old 1/2 turn once the washer has seated comes out about right.

When I was a kid in the on my old mini with an iron head, just ram it in as tight as it'd go - but I'm not keen on having to helicoil spark plug threads on ali heads, so I'm a bit more careful these days.

I did JB Weld a spark plug in once on a knackered old motorbike we were messing around with. It was so knackered that even JB Weld seemed a bit posh for it.

[Ben_r1]

Did the JB weld work though?

[Mɐʇʇ]

Hell yeah!

It's actually a very good epoxy, IMVHO. Pretty much the best mainstream stuff you can get without going super specialist and ££££

[james85]

The thread was sorted with a helicoil , I didn't do it myself got the garage to sort it.

The spark plug that caused the issue we still don't know 100% why it did that but yes its possible even too tight or not tight enough. Everything else was fine except the coil on the knakered spark plug.