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The mkiv Supra Owners Club

Fog horn noise when backing off


Steve Cargill

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Just got my car running and am getting a very strange noise now - it didn't make it before the rebuild.

 

If I blip the throttle then as the revs are dropping and get back to tickover I get a noise coming out of the air filter. It sounds like a fog horn crossed with a kazoo.

 

I've done a search and there are a couple of possibilities as to the cause and it seems like it's possibly harmless.

 

Anyone got ideas on this?

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Originally posted by Ian C

About the only bit that has to do anything on overrun is the BOV so it sounds like suspect no.1 to me :) You'll hear it's internal noises easily due to having an aftermarket air filter.

 

-Ian

 

I used to get a good noise from the BOV, out of the filter I assume, when coming off boost. As I've new engine and turbos - about 40 miles so far - I've done no more than spin them up, no +ve boost yet. I get this even after a slight blip from tickover.

 

If it is the BOV from memory it's just a few pipes clipped on so should be easy to change.

 

I guess that could well cause problems when I start boosting, depending what it's actually doing.

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Congrats on getting the car back - about time! :p

 

Anyway - mine has always done that since I had my HKS mushroom fitted, I just assumed it was normal.

 

I previously had a Blitz SSBOV (old shape) and have recently had that plugged and reverted back to the standard BOV as the Blitz was dodgy/leaking - not noticed the noise since, not saying it hasn't done it though, just that I've not really listened out for it specifically.

 

I'll try on the way to work tomorrow and let you know if mine still does it.

 

....not that any of that explains WHY! :blink:

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Guest Terry S

Steve did you change to Stage 3 turbo's. I have heard a few cars make this noise all with JPS stage 3's. Just a function of the turbos.

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Originally posted by Terry S

Steve did you change to Stage 3 turbo's. I have heard a few cars make this noise all with JPS stage 3's. Just a function of the turbos.

 

Errrmmmm, yes :innocent: I'd be surprised if that was the case as it does it after a very short blip. Open bonnet, gentle blip using throttle butterfly - fog horn.

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Guest Martin F

I would check your BOV first but if that is OK, then it's most likely to be a problem with the reed valve. As somebody previously mentioned the americans suffer from this a lot and my car also does this on occasion when coming to a halt.

 

As far as i can tell it's not a major problem, but do a search on Supraforums for 'Frog sound' or 'reed valve'

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Originally posted by Martin F

As far as i can tell it's not a major problem, but do a search on Supraforums for 'Frog sound' or 'reed valve'

 

Agreed. It's deffo the reed valve that stops pressure from No1 turbo going into the inlet of No2 when only on the No1 turbo.

 

It's often heard when opening up the induction and/or fitting a BOV. Nearly all of the time it's nothing to worry about. I've never changed one yet anyway.

 

Regards,

 

Nathan

TDI PLC

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Thanks, I've had a search on Supra Forums and they seem to have had mixed sucess changing the reed valve. The consensus does seem that it's not a problem though.

 

I was just a little concerned as it happened after the rebuild.

 

Just one more way of frightening pedestrians :p

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  • 1 year later...
Originally posted by Terminator

Nice one Steve so now it must be Barrrppp, whoooosh ptttisssssss croak.

 

 

Classy;)

 

Hmm I noticed this after removing the stock BOV (already had a blitz on it). Now before the BOV dumps I get the whiffle whiffle or fwshfwshfwsh flapping noise from the right (confirmed its the hks 'shroom), then after a second I get the low moan.

 

aaaooooohhhw. Just like that kinda frog noise i guess.

 

I'm told this is an echo on the turbos (I think they are stage 2's,. def hybrids, and capable of 1.4 bar). I favour the BOV straight FWSHH noise tho.

 

Anyone confirmed this is just a noise and nothing to worry about? As I said it wasn't there with the stock BOV that I could hear but now I hear it whenever I back of the throttle. Long as it isn't serious, and/or doesn't sap my power - the car;s already running .2 bar under what it should :(

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