Noise from air intake

[Johan G]

I have searched through other threads to find some information regarding noise from the air intake. On my S3C I get some noise from the air intake. Sounds a bit whooshy, like a vacuum cleaner maybe (like air flowing through a hose... which it obviously does too, but...).
I have checked that the air filter is correctly in place, which it wasn't but now is. Still got the noise though. Is it normal to have a bit of whooshing from the air intake? I have a Pipercross air filter fitted. Maybe I shouldn't worry?

(Will buy the Bible soon, guess lots of my questions get answers in it...)

Cheers
Johan

[roy_allen]

As far as I know this is completely normal provided it isn`t all that loud, 'cos if it is there may be an air leak somewhere. I know that air filters such as K&Ns make even more noise. You`ve heard of the term 'induction roar' I`m sure.

Roy.

[Psychobert]

roy_allen said: I know that air filters such as K&Ns make even more noise. You`ve heard of the term 'induction roar' I`m sure.

Roy.

True.. My K&Ns make a lovely noise.. Difficult to hear over the pipe mind you..

[tonystiny]

Psychobert said:

roy_allen said: I know that air filters such as K&Ns make even more noise. You`ve heard of the term 'induction roar' I`m sure.

Can also be heard on Novas with the air filter removed!

[Johan G]

I feel less worried now. Many thanks!
This sound I have is present already when the engine is idling. It doesn't change very much if I rev the engine up to say 3000 rpm. Guess it is a normal sound when thinking of how thin the Pipercross air filter is, not much material there to silence noise from the air intake hoses. Well I will still look for leaks to be sure that nothing is wrong.

Cheers
Johan (by the way, got my door locks fixed soon, will update that thread when done)

[Johan G]

Thought I'd pick up one of my old threads since I've been looking into this a bit again lately.

After removing the air intake hoses to inspect them for leaks, I started the engine and it was then obvious that the air intake noise I have on my S comes from inside the small hole in the throttle body leading air to the idle speed control valve. Since there are no airflow meters on my S this noise gets out through the air intake.

Does anyone have the same noise? Maybe it is a matter of TADTS? Anyway I'm going to remove the idle speed control valve and clean it and have a closer look inside the small air channel leading to the valve to see if anything is wrong in there. Is there any precautions I should take when removing the idle speed control valve, apart from getting a new gasket to make the seal air tight when putting the valve back?

Any help or advice would be much appreciated.

\ Johan

[andyf007]

It sounds as though it is sticking. I have a fault on mine and I have it disconnected, but if I reconnect it with the engine running, it creates the same noise you describe for a couple of seconds or so, then settles down to nothing.

Yours may be stuck open slightly?

Andy

[Johan G]

Yes, that's what I hope has happened.
It gets more quiet when the engine warms up, but the noise is still there. And it has been awfully annoying ever since I bought the car. Can't wait to get rid of it.

Edited to add: And the car is sometimes a bit hard to start when warm which I suspect might be caused by the same problem. It's like if the idle control valve doesn't move enough.

Johan

>> Edited by Johan G on Wednesday 30th June 12:53

[andyf007]

Sounds about right then. When the throttle pot tells the ecu that the throttle is closed, it should then open the idle control valve to allow a small amount of air to bypass the butterflies and enable smooth idling. There is also a small hole in the butterfly in throttle no.2 which allows air in too, but this is an uncontrolled amount and would only maintain a lumpy idle if the control valve fails. By also using the information from the coolant temperature sensor (and the MAP sensor on S3's), the ecu will determine the amount of idle valve opening required to maintain fast idle and the mixture for cold starting etc.

Hopefully it's just stuck open or the gasket has gone and not the ecu opening it too far. You could test by unplugging it and see if it stops the noise. If it does then the ecu is causing it to open.

Andy

>> Edited by andyf007 on Wednesday 30th June 13:16

[Johan G]

Many thanks, Andy!

I'll do some testing, probably sometime during the weekend. Will post results here afterwards.

\ Johan

[kentishS2]

You're not alone!

Mine only makes this noise whilst cold.

Or, it did prior to going in for the engine rebuild but I'll see how it is when I get it back. If it's the same I'll check out the test procedures mentioned here.

[Johan G]

Just want to mention that a new gasket for the idle speed control valve has finally arrived at the local Ford dealer. Will go and get it later today and hopefully I'll investigate the noise further tomorrow.

Johan

>> Edited by Johan G on Monday 12th July 08:35

[Johan G]

I have now removed the valve and had a look inside it. It needs to be cleaned inside. But what should I use to clean it? Would some sort of spirits be the right thing to use? Maybe something based on etanol?

\ Johan