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Discussion Starter #1 (Edited)
Hi,
Wondering if anyone has any suggestions on this.

Just this week, I've noticed a noise on my 159 (1.9 16v) that I've never noticed before (though it may just be that I hadn't noticed it)!

It's not quite a buzz and not quite a rattle, but something along those lines. It's fairly low frequency and seems to be coming from the front right of the car. It sounds like resonance

It manifests itself between 1,000 and 1,500 RPM, especially on a trailing throttle. If I slip into neutral and coast up to the lights, it almost always happens as the revs settle through that zone. Now that I've noticed it, it's driving me bonkers!

Does this sund familiar to anone? Any idea on what might be resonating, or should I just open the bonnet and listen? The problem is that just revving from idle doesn't always seem to trigger it.

I'd appreciate any help!
Thanks.
 

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I had something similar to this. It drove me mad. It strangely came from the fuel filter (bolted to the bulkhead under the bonnet in front of the driver).

For some reason the fuel lines to and from the filter seem to buzz/hum. I (on advice from this forum) put a plastic cable tie around the two fuel lines and it stopped it dead.

Worth a try!

James
 

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It sounds like the same problem I had which apparently can be cured with an updated fuel line made of a different material. I havent had it changed just moved a few pipes about under the bonnet near the bulkhead and it seems to have stopped...

you can test this because if you sit at tick over with the noise present as soon as you touch the throttle (fuel pump speeds up, resonant frequency changes) it stops, thats why you dont get it on a trailing throttle.

Thats the theory i was told anyway....

Problem i found is finding the cause as you cant hear it under the bonnet....
 

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Discussion Starter #4
This morning I did what I should have done first - opened the bonnet. I discovered that the plastic engine cover had detached from one of its clips. Popped that back on, thought 'great, problem solved'. Except - it isn't.

The noise has definitely decreased, and the rattle component seems to have gone. It's now kind of like a snuffle, if that makes sense - I can't think of a better way to explain it. Not fuel pump, I think - lines there seem fine. I'm wondering if it might be an exhaust bracket?

On the front of the engine, to the left (as I face the engine) of a metal cover with a do not touch warning on it, a large black pipe connects to the engine. there seems to be some oilyness around the connection. I'm wondering if that might be the source of the problem.

As always, help appreciated. I'm driving myself mad coasting up to traffic lights just to replicate the problem!
Thanks!
 

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The fuel pump issue is hard to find, i cant find it now, just know that if i disturb the pipes it disappears.... of course it could be an entitrely different issue... it does sound like a heatshield maybe, had something similar on my 156
 

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I Had a similar noise ended being to little grommets in air filter box bottom front left edge. superglued them in noise now gone. :)
 

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I have that air box noise too.... awful, dealer got rid of it for about 18months but now its back... i thought they were flap valves for the air flow and that you couldnt seal them though?
 

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I think the clips are to allow water to drain out of the airbox and stop dirt entering, I have put a couple of O rings between the head of the clips and the housing to stop the rattle. I was reluctant to glue them in in case water did enter the housing and couldn't drain out. I think removing them all together might be a better option, they are easily taken out once the cover is off.
 
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