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Discussion Starter · #1 ·
Hi there,

As mentioned in another post I've noticed a louder than normal whine from the engine of my 02 MCS (75,000 kms).

I'm not sure what's creating the whine but I thought I'd see if anyone had any ideas. The whine is related to engine speed and would not be described as rough or harsh although I suppose it could be a bearing on its way out (belt tensioner or water-pump).

Strange thing is that the car seems more responsive, and dare I say, faster. It could be my imagination, but it feels like the supercharger is working harder; hence the title of my post.

The car is bog standard and whilst it was never slow, it did have problems getting off the line fast. Now it's much easier to drive.

I'm just wondering if I've had problems with the by-pass valve (always suspected it to be the cause of the yo-yo effect that I occasionally experience). Could the valve have been partially open allowing boost to "escape" and now it has closed allowing the supercharger to do its job properly?

Apologies for the vague assumptions; we're in the middle of major house renovations and I haven't had time to investigate this properly; I have to fight various trucks for spare driveway space :). I'll post again when I find out what's happening.

Hoping some of the experts out there have come across this before.


Cheers,

Dave
 

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dyno-mite, might not....
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just a guess

lost the lid of your airbox, or paper filter broken?

or if CAI, pipe come loose
 

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Discussion Starter · #3 ·
Thanks for the suggestion Alski.

I'm fairly sure I would have noticed these, but I'll have a closer look, especially the suggestion of a damaged air filter.

BTW, has anyone done a little drawing of how the intake system of the MCS is plumbed; where the bypass valve sits and where the excess boost is vented to. It would help me understand how it works.


Cheers,

Dave
 

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Discussion Starter · #4 ·
Carried out an oil change over the weekend and at the same time fitted a boost gauge to start my investigation of what the hell's happening with my MCS.

Whine had not got worse over the last two weeks, so I doubt a bearing problem now. I'm more and more suspecting that the bypass valve was stuck open for a while and has now "fixed itself".

Whilst I was fitting the boost gauge I checked the actuator lever on the bypass valve and everything seemed OK.

Can anyone tell me what boost I would expect to see on a standard pre face-lift MCS?

I'm seeing about 5psi boost whilst taking off briskly at lights and a maximum of about 11psi at wide open throttle.


Cheers,

Dave
 
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