Leon Cupra 1.8T rattle/strange noise on boost

[Col]

Just this week my Leon Cupra 1.8T has developed a strange noise on boost under load. It doesn't seem to happen in first gear, but does in others and seems to be over 2k rpm and while under load.

The way I'd describe it, it sounds like a boost leak and rattle together, but I have checked all hosing and can not see any tears or perished hoses. I have changed plugs and recently coils.

Having also scanned it with my VW scanner, it did give a knock sensor high voltage p0328 fault months ago, but when I cleared it that never came back. No other fault codes are present and it appears to be still pulling ok although I'm reluctant to give it much.

It has only 95k miles so it's not like it's done huge mileage.

Anybody any ideas?

 

[DrewCole]

My advice would be to just strip the boot lining and double check for any loose connections, or make sure the tools aren't moving around with the spare wheel.

I bought some thick foam and have it stuck behind various panels to prevent rattles!

On a 14 year old car... you will always be chasing rattles.... always!

 

[mty12345]

Hard to say without hearing the noise mate, but it could be knock from the engine if it only happens under load and on boost!

Do you have vagcom/vcds? If so. run some logs and see whats happening with boost and fueling etc.

 

[DynamicD]

Do they have engine covers? My 8L S3 engine cover used to rattle under load, so i removed it and replaced with a newer one/better gromits.
Dave

 

[Col]

Thanks for the replies guys and apologies for the late reply.

I had a friend with VCDS scan it and nothing came up at all to worry about. The only thing he could see was that my throttle position sensor was off, I think he said it was running at 85% but cant remember exact figure. Otherwise he couldn't find a fault.

The noise now I feel is coming from the turbo/down pipe area. I will try to get a video with some sound.

I ordered a crankcase breather pipe and changed it out, still the same but the old one wasnt great and had a small bit of sludge in it.

Could a blow in the down pipe or exhaust in general cause a rattle and boost leak kinda sound at certain revs only? The turbo still feels like it pulls generally fine, but it does feel down on power.

 

[Col]

Just to update this. The sound did get a little worse, so finally I managed to get a contact who could give me access to a lift.

As I suspected, the flexi part of the downpipe was blowing.

So a trip to an exhaust centre and €120 later and it's fine again. Although it's a tough one to get to with limited access.

Either way it's sorted now and pulls again just fine : )