Exhaust rattle on cold start

[RossDagley]

As I understand it, the start up rattle is pretty normal, it's to do the emission regs. My 2012 one does the same.

An increased noise from the front of the car is normal - it's air being drawn into the exhaust to speed up cat heating for emissions / efficiency. A rattle from the back is not normal.

[S4WON]

Hard to tell where mine is coming from to be honest maybe ill do a vid

[johnnydog]

I'd agree with Ross on this - on cold start up the noise is most likely to be the secondary air pump which forces air into the exhaust to reduce emissions until the cats begin to warm up. It stops after about 30 secs, and the noise goes and the initial increased tick over speed drops. On mine, it actually sounds a bit rough to be honest, but Audi say its normal.

[carsarecool]

I'd agree with Ross on this - on cold start up the noise is most likely to be the secondary air pump which forces air into the exhaust to reduce emissions until the cats begin to warm up. It stops after about 30 secs, and the noise goes and the initial increased tick over speed drops. On mine, it actually sounds a bit rough to be honest, but Audi say its normal.

+1. Most cars do it....with a noisier exhaust it does sound a bit rough. My Milltek sounds like it's about to spit its innards out if you pull away very soon after start up!

[S4WON]

Here it is lads (and Lady P if you are still around)..

https://youtu.be/me1aXXlmSZY

also, if you love Beanie Boos, please do check out the rest of my videos! some have over 50k views!!
There is also my old B7 on the rolling road day hidden in there somewhere... not that you'd be interested in that sort of thing though!

[Snotsicle]

That does sound different to mine - the initial whoof/clatter/induction noise is normal, but yours sounds like there is a rock or something metallic rattling around in there as well.

[S4WON]

Which bit is it likely to be stuck in? And where is it?

Please also assume I know less than nothing about mechanics when responding!

[rspj]

Yep about same with me on start up

[Snotsicle]

No idea, sorry. My knowledge of such things is probably similar to yours but I was just observing that it doesn't sound quite the same as mine!
No doubt someone else will chime in shortly with some practical suggestions.

[CRSRS]

Mine sounds exactly the same, was going to get Audi to have a look it next time I was in. Anyone had a response apart from.... ' they all do that''

[Brooner]

they all have a rough start up then settles out after about 30 seconds that's what mine is not a rattle after i checked again

[Rallyz]

Sounds like mine too. The sound is just like a loose heat shield near the engine, but isn't, if you see what I mean. If the rattle carried on after the initial start up, i.e. after the revs drop and you get that nice "whoofle" sound, then there would be a problem.

[RossDagley]

Sounds exactly like mine. Don't sweat it.