Weird noise, please help!

[SIR_LOIN]

Anyone any idea what might be causing this sound? 
Audi a3 1.6. 
I've had the car into Audi for diagnostics after my epc light came on an came back with a few faults. 
One mainly being the brake light switch which was bringing up a number of errors, after replacing that then light went off and the car seemed to run a bit better, (even though fuel consumption hadn't much) 
One of the other errors was an intermittent mechanical malfunction of my oil pressure regulator. 
Could this be a cause? 
Car has also been recently serviced with all spark plugs and leads changed, also all piping has been checked for leakages, and I've even had it compression tested with no issues to be seen . I have also had the exhaust checked twice for holes etc and nothing! 

It's totally baffling me at this stage, local mechanic can't work it out, audi want in excess for €400 for a further diagnosis. 
Any help greatly appreciated!

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[Dan3222]

Your exhaust sounds like it's rattling on something. But there is a girdling noise too by the sounds of it.

can you hear any noise from the air filter housing? Take the lid off and filter out. Start her up and see how she sounds there.

[cliffcoggin]

I agree with Dan about the exhaust rattling against something as one possibility. It also sounds a bit like a loose baffle inside the silencer.

[Luey]

I would suggest going through the basics first.

I too agree it could be something simple such as the exhaust rattling against something, a broken baffle is certainly a possibility.

The exhaust is slung on rubber mounts, when the car is cold if you give it a shake you might be able to hear a broken baffle. 

When it's cold again with a thick glove you could also cover the exhaust (only for a moment) see if the sound stops.

Anything inside the exhaust should in theory only rattle if there is airflow to move it.

[SIR_LOIN]

Thanks for the quick replies guys, appreciated! 

It's been pouring rain all day so I will get a chance hopefully tomorrow morning to check it out a bit more and will report back. 

I thought it might be the honeycomb !Removed! inside the cat but it does also sound like a slight misfire. 

 

 

[Luey]

I had another listen with headphones. It could very well be a misfire. It doesn't mean it's something too sinister however.

As I said definitely go through the basics first.

If you take us more audio we might be able to tell you more.

[Dan3222]

If it is the exhaust, internal, then you could go old school. Have the car safely raised so you can go underneath. While she is ticking over use a large screwdriver, hold it to the exhaust silencers and the handle to your ear. You will be able to pin point literally the exact bit that is rattling. Obviously you would need to replace that silencer.

is it was a missfire you would feel it when driving away, especially at low speeds I would have thought.

[SIR_LOIN]

23 hours ago, Dan3222 said:

Your exhaust sounds like it's rattling on something. But there is a girdling noise too by the sounds of it.

can you hear any noise from the air filter housing? Take the lid off and filter out. Start her up and see how she sounds there.

This morning got a chance to do exactly as you said and no noise coming from the air filter housing or anywhere around it.
Pulled the newish filter out and started her up and didnt notice any diiference at all :(

21 hours ago, cliffcoggin said:

I agree with Dan about the exhaust rattling against something as one possibility. It also sounds a bit like a loose baffle inside the silencer.

Have a quick read below ;)

20 hours ago, Luey said:

I would suggest going through the basics first.

I too agree it could be something simple such as the exhaust rattling against something, a broken baffle is certainly a possibility.

The exhaust is slung on rubber mounts, when the car is cold if you give it a shake you might be able to hear a broken baffle. 

When it's cold again with a thick glove you could also cover the exhaust (only for a moment) see if the sound stops.

Anything inside the exhaust should in theory only rattle if there is airflow to move it.

Hey Luey, so i got a chance this morning to get under the car and check the back box/exhaust pipe up as far as the cat, i rattled it as best i could and checked all the mounts which seem to be fine and no rattling noises coming from inside the box.
Posted a video couple of videos below again, all cold start from under the car.
Thing is it seems to be intermittent, it was making the noise when i started it up, went inside to get a cloth/plastic bag to do mas you suggested by covering it and it seemed to be fine...

20 hours ago, Luey said:

I had another listen with headphones. It could very well be a misfire. It doesn't mean it's something too sinister however.

As I said definitely go through the basics first.

If you take us more audio we might be able to tell you more.

Praying i can find out before trusting in Audi dealership or a local mechanic, its more frustrating then anything else, They wanted 300 euro to just replace the brake light switch which cost me 14 euro and fit myself :0

1 hour ago, Dan3222 said:

If it is the exhaust, internal, then you could go old school. Have the car safely raised so you can go underneath. While she is ticking over use a large screwdriver, hold it to the exhaust silencers and the handle to your ear. You will be able to pin point literally the exact bit that is rattling. Obviously you would need to replace that silencer.

is it was a missfire you would feel it when driving away, especially at low speeds I would have thought.

Id love to that mate but im really busy with work during the week and the only way il possibly get to do that is by paying the likes of fast fit to put it up on the ramp, and those guys dont know their arses from their elbows half the time so getting them to locate the problem might be a problem.
Ive already had it up twice with them trying to locate what i thought was a hole in  my exhaust but they couldnt find anything.
Next step for is is the local mechanic, i guess after getting lucky with the brake light switch i thought i might be able to sort this myself also without forking out a fortune!!
I personally think shes not idling right either, slightly jumpy when stationary but nothing excessive, nothing on the rev counter to show a jump or fluctuation in revs but doesnt feel right if you get me?

Once again, thanks in advance guys! 
Love from the emerald isle ;)

All vids below are this morning from cold start btw....

 

 

[SIR_LOIN]

Sorry for the extra post, still getting used to using the forum :(

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[Luey]

I am honestly stumped if there is no leak and it's not rattling on anything.

I wonder if it's an exhaust valve sticking or something. It may not be anything that sinister.

Have you tried running a shot of Redex through your fuel tank? I recommend it regardless it'll only cost a could quid.

I do it monthly to keep my engine clean, obviously more effective on a diesel like mine but I've seen it make huge improvements in all types of cars.