Hissing sound possible vacuum leak

[fieldy107]

My Leggie is making a hissing sound when I give it a bit of foot. When I first bought the car it was doing this but It was fairly quiet and I thought it was just the sound of the turbos working, but it seems to be getting louder and Im only having to give it a bit of gas to hear it...

What could this be? A boost leak?

 

[naughtika]

BOV is probably leaking..

*edit* rephrasing my question..

question.. when you plant your foot on the accelerator quickly when and boosting (lo or hi).. does it feel like its surging, as if the motor would like to stall or just normal?

 

[mills_88]

I had a kind of hissing noise once and that turned out to be one of the vacuum lines running to the "110 degree elbow before the manifold" had come off slightly. May be the case here, may not but could be worth a try.

 

[frozen]

one of my O Rings had a bit of a crack, causing a boost leak, that made the sound you're describing. Ive also had the sound when my muffler colapsed, but that also went hand in hand with mass power loss, where as the boost leak not so much - the car felt almost as good as always.

I would almost bet money that you have a leak in one of your pipes, as in the ones between the turbos and your throttle body.

 

[fieldy107]

Yeah doesn't feel like its gonna stall or anything, it still goes alright. If there is loss of power its not huge...it feels ok. Its fairly loud though, like someone is blowing in my ear

Also it might be increasing my fuel consumption, after a full tank it was sitting at 110kms at 3/4 full mark on the fuel gauge, then the hissing sound got louder and my fuel gauge is now sitting at the 1/4 mark with only 220kms on the trip.
So 110kms out of my first quarter of a tank and 110kms out of half a tank, seems like its doubled fuel usage. Cant be sure of this until next time I fill though

 

[Guest]

Do you have a boost gauge or controller fitted in the cabin?

 

[fieldy107]

nope

 

[frozen]

check your soft pipes for a leak, as in if a hole has appeared, the fact its louder now might mean it got bigger.. they balloon quite a bit under boost, so that would make the hole get gradually worse.

I can still almost guarantee its going to be a boost leak. I had one when my seal was stuffed and it didnt feel really any less powerful, but yeah, fuel usage will take a fall, and it would definately be losing at least a little bit on power.

Run over all your pipes for leaks, and check the clamps are all tight. Start at the turbos and work your way around. Also as others have said, vacuum lines if they have popped off, though by the way you're describing that its not stalling, lacking much power or anything like that, id probably assume a much smaller leak like mine was. Still loud as hell hissing sound though, no matter the size of the leak

Definately sounds like a boost leak though.

 

[happymatch]

how do you check the leak? i mean how do you check for the small crack?

 

[frozen]

soapy water?

 

[deadlast]

Hi All,

Fuel economy has been worse since the mods done recently. The idle screw was adjusted out as well by the mechanic and now it hisses quiet loudly. What position should the idle screw be in? Screwed all the way in? Is the hissing normal? Cheers all.

 

[VOLK]

No, hissing isn't normal. Idle screw shouldn't be all the way in and can only be adjusted if the ISC is disabled.

 

[Guest]

Hi All,

Fuel economy has been worse since the mods done recently. The idle screw was adjusted out as well by the mechanic and now it hisses quiet loudly. What position should the idle screw be in? Screwed all the way in? Is the hissing normal? Cheers all.

Yes the o-ring on the idle screw is stuffed.. very common boost leak there. Idle screw should on average be 2 -3 turns out but it varies from car to car.

One important thing to not is that you cannot simple adjust the idle by turning the screw, because the ISC will try to counteract your adjustment. It's recommended to disable the ISC using EvoScan or a Mitsubishi MUT tool. Alternatively, turn the car off and do the adjustment then restart to check.

Right now you will need to replace that o-ring, disconnect your battery to reset the ECU, adjust the idle screw 2 turns out, restart the car, let it idle 15 mins with air con on to relearn itself, then go for a drive for a bit, and after that do the adjustment procedure as mentioned above.

 

[deadlast]

Where is the best place to source the o-ring, any mechanic/car place?

When I got the car, the screw was wound all the way in, after all the recent work, the mechanic wound it out, so I gather it being all the way in isn't normal from the above. In the interim, should I leave it all the way in until I get the o-ring, car was driving fine this way before?

 

[Guest]

To be sure it doesn't leak again you need to get the correct one, send me a PM.

Being wound all the way in would mean you had leaks somewhere that it's trying to counteract.

 

[deadlast]

Hi All, below is a link with the noise i'm hearing from my engine bay, is it normal? Cheers

[video=youtube_share;bsLoAP2h1VA]http://youtu.be/bsLoAP2h1VA[/video]

 

[fieldy107]

Hi All, below is a link with the noise i'm hearing from my engine bay, is it normal? Cheers

Not really the thread for these questions and couldnt tell much from the vid but if you have hissing coming from that area it might be rear injector seals, a worn gasket or a leaking vac line. Maybe try spraying some soapy water around while someone revs the engine, see if you get any bubbles.

 

[deadlast]

Cheers mate, reason I posted was that I was trying to ascertain why my fuel economy is worse than before I got a lot of stuff fixed. Cheers

 

[Guest]

Posts moved to a more appropriate thread...

Soapy water won't work very well under vacuum with engine idling. Do a proper boost leak test to find the source.

Also check that your throttle gasket has been fitted correctly. You should see a small tab sticking up as shown below.

 

[deadlast]

Gasket is definitely correct, so another boost leak test it is.

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