Hello all,

I recently noticed a faint siren sound similar to being followed by a cop car. I have had my car for a year and a half and I am very familiar with all it's noises and I know for certain this is a new development and not in my head.

The whirring sound comes on exactly between -1 and 6 psi of boost. It is most noticeable in the cabin with the windows closed. when the windows are open it is not as noticeable(maybe its the added wind noise?). I can drive with on-off throttle to induce it specifically in that boost range.

2 theories. 1, my downpipe was butt-up-against my lower tie bars and may have caused stress cracks on the downpipe, exhaust manifold or turbo housing? But i think that the cast manifold and housing are hella tough so I am thinking, hoping that the bolts holding the flange just stretched and now allows a leak between the flanges? I can't feel any exhaust leak. But I would think that would cause more of an exhaust pulse sound than the turbo spool siren.

2, my boost gauge is leaking in the cabin, but once again it would be more of a spray can than a siren sound.

It truly is a weird phenomenon, especially since it seems to eminant from inside rather than out.

If there is someone who has seen this problem first hand I would greatly appreciate advice for a fix.

Thanks

 

ummm more specifics please. mods done, year, etc...

 

I have just a buschur stage 1 with larger intercooler. The funny things is that the car runs perfect. Boost comes on fine, the power is there, there is no loss of boost. Just a siren-like sound.

What-the-??? could amplify the trubos noise?

 

1st and easiest thing to do is.............
http://www.vfaq.com/mods/ICtester.html

 

Thanks matt55:

Confirm your system will hold at least 15 psi for at least 10 seconds without dropping down to 13 psi and if it passes leak test we will go from there.

Good luck

 

this may sound stupid but you do this while the car is running? so that the turbo wont seize up? or with the car off?

 

yea , car off

 

I think I know the sound you are talking about. I have heard it on my car. First time I noticed was a while ago and I have gotten used to it. The first time that I heard it was the first drive after I installed some new parts, one of which was a new MAF pipe on my intake so I assumed that the new part was allowing me to hear more of the sound the turbo makes as it begins to spool up. The car ran fine, just like it did before I installed the parts so I didn't think anything of it. I am into Buschur stage 3 by the way.

 

matt55 double check your sig...i dont think you have only 255hp...i think you have a 255lph walbro... lol

 

It's probably related to the LICP connection (or lack thereof).