Turbo whine on decel?

[Talondvr]

‪Turbo whine‬‏ - YouTube



This noise is only there when the turbo is winding down after i let off the gas. It sounds loudest coming from the air filter so that's what I was trying to point the camera's mic at.When boosting or cruising it sounds/works fine. I am still breaking in clutch (and rear brakes) so I'm not getting on it much. The turbo should be getting oil fine -no leaks- (how to verify this?) checked for boost leaks (all sealed up real tight - k, maybe a little through the Throttle shaft seals, on the fix it list).

Got bout 350ish miles since the new Head gasket and clutch. Noise there for bout 50 miles tops. Its pretty consistent cold or warm, the car was +80% normal temp in the vid. Between shifts its fine if i boost 5 psi or so (bout the most i've pushed it) but only makes the noise when letting off the gas when i have low to no boost (2 psi or less) right around when the engine is about at idle speeds.

Any advice on how to verify what needs to be done W/O just throwing parts at it and praying (### im broke for a bit) is MUCH appreciated.

profile up 2 date

 

[gofer]

Its your bov and thats normal, just make sure the spring is tight enough in it.

Wobble's Guide

 

[red92tsi]

My Greddy S sounded like that too.

 

[uberswede]

I had that EXACT noise. It was driving me absolutely nuts. I just finished swapping a 1G into my '97 Talon.

As gofer mentioned above, we ended up finding the noise coming from the BOV. I don't really know exactly why it was making the noise... maybe because the BOV I used hadn't been used for quite some time, and I can only guess that it wasn't oiled up or something... but after putting some mileage on the car, the noise has since stopped. I'm at almost 1300 km's on the new motor, and haven't heard that noise for quite some time.

My best advice then is to just give it some time and see if it stops on its own, rather than ripping your hair out trying to fix it (if that ends up being the case). Chances are, since you have a DSM, there are probably other problems you could be spending your time worrying about.

 

[Talondvr]

Thanks for the link gofer. I haven't seen that one yet. I have been trying to get the bov adjusted lately. I have recently done the 1 spring mod and cleaned and greased the bov. This was done right before the noise came about, now that i think of it.

It seems to flutter no matter what i do. Tried it soft, hard, w/ 2nd nipple and without, 1 spring mod, 2 spring stock, and every combination of the settings. I got it to release ok but it still has a slight flutter (2-3 times) before it "pops off" (both nipples connected, about half way adjusted between sft/hrd). The noise does seem to be coming from in the filter (seems louder with my ear to the filter than next to the bov). That plus its only been doing it since I took off the gm maft and went back to the 1g mas w/recirc (a day or so after actually). Thats why I was thinking the turbo. I did check for shft plat and there was none. (supposedly a brand new turbo when i got the car )

I'll post back any updates when i get some things tweaked. (like the breather hose needs to be plumbed back to the intake - today hopefully)

Keep the thoughts coming and THANKS!

 

[gofer]

How do you have the vacuum line routed going to the bov?

 

[Talondvr]

I have the top nipple going to the underside of the intake mani, bottom nipple plumbed to a tee between the j-pipe and the ebc. Going to remove the Tee and make the adjustments per the link you posted. I'll post back after i give that a try.

to: red92tsi -> did your noise "just go away" like uberswede stated?

The breather hose of the valve cover is just hanging down by the trans. I still need to put a nipple on the intake pipe. My vacuum is affected (22.5 inhg at idle right now) with it like that. I'm assuming and should correct that in order to get a proper bov adjustment or am I thinking about that wrong?
________________________________________________________

Well I got the breather going back to the intake (I also put the smaller spring back in the bov) and adjusted the bov according to the above link. Well.. The whistle/whine is gone. The plunger/seal on the intake pipe side of the bov seems to not open with the screw all the way out then in a bit past contact.
I think i will try W/O the 2nd spring and adjusted properly. It seemed to adjust fine before like that, I just had it all out so i put the other spring back in before road testing (glad its easy to rip it all out again)

Big THANKS for all the help!!