Heavy breathing

[bernhund]

So I spent £3.5k at Mole Valley a couple of months back, 3 weeks later lots of smoke and another £3.1k. New rear turbo, stainless manifold, gaskets and bolts etc. So now the car sounds very smooth compared to before, but is there an issue? Because it sounds like I've got an old man behind me fast asleep! Heavy breathing sounds.... in.... and out.....in......and out......in......and out. I hear this when the car is idling or if I'm cruising gently. Boost gauge reading -0.5 at rest. When I turn the engine off, one long sigh and then silence,start her up...... nothing, then gradually it builds.... in.... and out!
The car seems to be running ok apart from this noise, except since getting it back it occassionally lurches/kangaroos all of a sudden like the engine dies momentarily twice in about 2-3 seconds.
Your thoughts and opinions gentlemen please.

[R0162]

My car makes the same breathing sound when idling, you hear one filter breathe and then the other, i personally like the sound, the noises give it character.

Momentarily dieing is not something i encounter though, sounds like tickover could be too low, my car ticks over at about 750 - 800.

[Gadgeroonie]

did it happen after the new turbo was fitted

could be the actuators are not the same pressure and one turbo works harder than the other

[daddysumo]

Gadgeroonie said:

did it happen after the new turbo was fitted

could be the actuators are not the same pressure and one turbo works harder than the other

Mike..... its at idle......
Mine does the same, as do others I know of, its a kind of compressor surge I think, as one turbo spins slightly faster and stalls the other and then the process reverses.

Don't hold me to this explanation tho.......

[hollowpockets]

Sounds like a reasonable explanation Steve, something to do with the length of the air filter-turbo pipes. Could it be that all the people who mention it have the air filters located on the bulkhead making it more audible?

Also could be that one turbo (the newer one in your case) is turning more smoothly than the other and the resistance or sticky spindle in the other speeds up/slows causing the noise.


G

Edited by hollowpockets on Thursday 4th August 12:23

[Gadgeroonie]

does it go if you raise the idle

could be due to the mass of the turbo being higher than normal and it just starting to spin at idle

[bernhund]

Sorry for the disappearance, I'm in LeMans!
The breathing sound doesn't bother me, it's just something I've not heard over the last 4 years before. Wondered if the kangarooing was to do with unequal pressures or something. Or, more likely the fuel pump fuse carrier!