Turbo noise & shuddering

[sydoggkdy]

Hello, My brothers Altea 1.9 tdi makes a sound like turbo chatter when you lift of the accelerator to change gear, sounds like this:

http://www.youtube.com/watch?v=dbc170fuIBk&feature=channel_page
http://www.youtube.com/watch?v=7CYalUxuYHk&feature=channel
http://www.youtube.com/watch?v=AySkvbp1zNQ&feature=related

I don't think it sounds right, as my old pd100 or current vRS never made any noise!


also, sometimes when in 5th gear the car seems like its juddering when accelerating

I thought that maybe the first issue could be a boost leak of some sort, but I don't know where to begin looking, any ideas?

and also whether or not the two issues could be related, as I'm hoping it isn't the DMF on its way out as its only done 45K miles.

thanks in advance, Si

P.S I made a new thread as I had no replies on the Altea section and couldn't just move it over.

 

[MJ]

i can quite confidently say that i have never ever heard that sound on a dielsel before... ever!

 

[Seatmann]

Holy ****, sounds like a crappy dump valve. I'll have to ask someone else about this one. Wierd.

 

[irishmanr26]

I hear this noise all the time around where I live on Boras and Golfs. Its usually a straight through exhaust that makes the noise.
I had it on my old ST Mondeo with a Powerflow exhaust on it.
Did the car always make this noise or has it just started to?

 

[sydoggkdy]

i can quite confidently say that i have never ever heard that sound on a dielsel before... ever!

Holy ****, sounds like a crappy dump valve. I'll have to ask someone else about this one. Wierd.

I've never heard it before either but it does sound like a crappy dump valve, believe it or not the forums where I found the links to the videos all love the sound and think its the best sound in the world

I hear this noise all the time around where I live on Boras and Golfs. Its usually a straight through exhaust that makes the noise.
I had it on my old ST Mondeo with a Powerflow exhaust on it.
Did the car always make this noise or has it just started to?

All the cars on the vids have straight through exhausts etc. but the Altea is bog standard.

It has always made the noise when we got the car at 37K miles but now at 48K we think its getting louder and happening lower down the rev range which leads me to believe its getting progressively worse.

Thanks, Si

 

[irishmanr26]

Have you got any vids of your car making the noise?
I had my Mondeo for a couple of weeks and the noise started to get louder until the exhaust blew off at the manifold

 

[Ptar64]

I heard a lorry today doing this went it drove past me, very loud! A really strange noise but it seemed to be driving ok :S.

 

[markyboy76]

Did you ever fix this my leon fr 1.9 tdi is doing it too its doing my head in, it isnt stuck VNT or DMF or broken exhaust hangers, i also decat it and no change. I put a foam filter in and now its even louder which means its definately chatter.

Puzzled, some have said they all do it but mine is pretty loud

 

[Seatmann]

This is all I've heard from someone so far.

"My dad has a ford 7.3 L Powerstroke diesel and it has no method of purging the intake of charge air when you lift your foot off of the accelerator pedal abruptly upon high boost, so the pressure inside the intake becomes higher than that of the pressure in the exhaust. this tries to spin the turbo backwards and makes the whistling noise when the air flows over the fins backwards inside the turbo as it is still spinning at +100,000 rpm. it kinds sounds cool on my dad's truck... but some say it could really damage the turbo."

No idea if it's helpful though

 

[markyboy76]

This is all I've heard from someone so far.

"My dad has a ford 7.3 L Powerstroke diesel and it has no method of purging the intake of charge air when you lift your foot off of the accelerator pedal abruptly upon high boost, so the pressure inside the intake becomes higher than that of the pressure in the exhaust. this tries to spin the turbo backwards and makes the whistling noise when the air flows over the fins backwards inside the turbo as it is still spinning at +100,000 rpm. it kinds sounds cool on my dad's truck... but some say it could really damage the turbo."

No idea if it's helpful though

Thanks for the help. No disrespect but I kinda know how it all works and why the noise happens its just a question of do they all do it? and if not why does mine? Im down to the valves that control waste and boost action of the VNT, VNT actuator not adjusted right or possibly a bad ECU map not working the VNT correctly but thats a long shot!

I have checked thus far:
Boost pipes, no splits or leaks found
VNT Vanes which are lovely and free
VNT actuator which seems to be moving fine when the car is revved
Decat to allow better exhaust flow, made it faster but did not change noise
Pipercross panel filter which has made the noise louder
VAG COM read no faults
VAG COM boost map shows a bit of a spike, slightly higher than spec boost

Other faults fixed which did not affect the noise before/after
New cam and followers beecause of some wear
Full service all filters and cam belt with water pump

 

[Seatmann]

You can try swapping the n75 with the egr solonoid for testing which could help with diagnosis but no they don't all do it. Did it do it before the remap? It might be worth asking some of the performance companies on the home page for more advice but I'll email someone I know who's fairly clued up on tuning etc.

 

[markyboy76]

You can try swapping the n75 with the egr solonoid for testing which could help with diagnosis but no they don't all do it. Did it do it before the remap? It might be worth asking some of the performance companies on the home page for more advice but I'll email someone I know who's fairly clued up on tuning etc.

I don't know for sure if its been mapped I haven't owned it long and can't contact the previous owner.

 

[Seatmann]

Well I've sent an email off to a guy I know who seems to really know his stuff so hopefully he can shed some light on it.