Soft puffing sound on deceleration

H

hppyd1and2

Member
Hello everyone. Second time questioning my car. 2009 e89 35i. I have only owned the car a year. I just noticed a puffing sound during deceleration. It sounds like it’s coming from the turbo area. Is this normal?
Second question. In sport mode I went to accelerate fast. The car didn’t do anything at first. Once rpm’s increased it took off like there wasn’t anything that would hold it back.

Thank you all for the help that I have received.
Dale
 
The n54 can suffer from turbo waste gate rattle but that wouldn’t really be a puffing sound, regarding the acceleration, is yours a manual or DCT, you may feel a slight turbo lag but normally it should pull well and then warp drive engages 😁
 
Thank you Chippie. It is the dcs transmission. That’s exactly what it accelerated but then just took off. Would the waste gate cause the puffing sound during deceleration?
 
Sorry. I didn’t read close enough. Any idea what the puffing sound would be? It’s only when you let off the throttle. I would think it would be louder if it was an exhaust leak.
 
hppyd1and2 said:
Sorry. I didn’t read close enough. Any idea what the puffing sound would be? It’s only when you let off the throttle. I would think it would be louder if it was an exhaust leak.
Click to expand...

It could well be the exhaust as when you let off the accelerator it does produce a slight burble/pop from the exhaust, it’s quite possible that what you are describing is normal, if you are in 7th gear and floor it, the transmission will drop a couple of gears and you will feel a slight acceleration as the boost builds and then you will feel the turbo kick in and away you go.
 
Also there’s a valve in the exhaust that is normally closed during normal driving but opens more when in sport and sport+
 
When you say 'puffing' sound.....is it like a quiet 'whoosh'?

I would be looking at it being turbo pressure escaping from the wastegates on lift-off. I am not sure about the N54, but most turbo engines these days have recirculating wastegates, so there should be no air pressure escaping if all is normal.

If you can get the codes read, there could be something showing up if there is a mechanical issue.
 
hppyd1and2 said:
Second question. In sport mode I went to accelerate fast. The car didn’t do anything at first. Once rpm’s increased it took off like there wasn’t anything that would hold it back.
Click to expand...

And that sounds like massive turbo lag, which would be a consequence of one (or both) wastegates leaking.
The wastegates direct the unused air pressure back into the turbo impellors to keep them spinning on lift-off, to reduce 'turbo-lag' when the power is applied again.

I would recommend getting it looked at pronto, as anything turbo-related in the N54 is very very expensive. wastegate problems are bad enough, but it can destroy your turbos, which is much worse; financially.
 
Pondrew said:
hppyd1and2 said:
Second question. In sport mode I went to accelerate fast. The car didn’t do anything at first. Once rpm’s increased it took off like there wasn’t anything that would hold it back.
Click to expand...


The wastegates direct the unused air pressure back into the turbo impellors to keep them spinning on lift-off, to reduce 'turbo-lag' when the power is applied again.

That’s not actually correct, the wastegate dumps the boost pressure to reduce turbo possible damage to the turbo from over spooling
“A diverter valve in a turbocharger protects the turbo from damage, specifically from compressor surge, by releasing excess pressure when the throttle is closed or when the engine is under certain conditions. By diverting the compressed air, the diverter valve prevents the turbo from spinning backwards or being overworked, which could lead to damage”
Click to expand...
 
Thank you all. It sounds like air releasing. It only does this when the car is moving and you let off the throttle. Especially noticeable coming down hills at slower speeds. I talked to someone and found a mechanic in our area. He only works on European cars. I guess I’ll just have to sell the wife to pay him.
 
Pondrew said:
When you say 'puffing' sound.....is it like a quiet 'whoosh'?

I would be looking at it being turbo pressure escaping from the wastegates on lift-off. I am not sure about the N54, but most turbo engines these days have recirculating wastegates, so there should be no air pressure escaping if all is normal.

If you can get the codes read, there could be something showing up if there is a mechanical issue.
Click to expand...

Thank you. I did get a code for low turbo pressure a while back. I didn’t have this happen then. It just did had the delay yesterday once and hasn’t happened since.
 
Chippie said:
Also there’s a valve in the exhaust that is normally closed during normal driving but opens more when in sport and sport+
Click to expand...


Umm, no one on the forum seems to know exactly when this valve opens or closes. I asked the question a number of years ago.

A couple of responses were: "It opens when the roof is open." "It opens only when the roof is in the closed position", etc, etc.

You'd have thought there was an actual formula published by BMW that shows when it open and closes. Nothing to do with sport and sport+ modes, as far as I can ascertain.
 
SV8Predator said:
Chippie said:
Also there’s a valve in the exhaust that is normally closed during normal driving but opens more when in sport and sport+
Click to expand...


Umm, no one on the forum seems to know exactly when this valve opens or closes. I asked the question a number of years ago.

A couple of responses were: "It opens when the roof is open." "It opens only when the roof is in the closed position", etc, etc.

You'd have thought there was an actual formula published by BMW that shows when it open and closes. Nothing to do with sport and sport+ modes, as far as I can ascertain.
Click to expand...

You are correct that it’s not just sport and sport+ when it opens, it also opens during normal/comfort mode, seems to be more when the throttle is fully open, there’s just more exhaust noise, burbles and pops that I thought could have been what the OP was hearing in sport+.
 
You must log in or register to reply here.
Back
Top Bottom