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Registered
2001, MY02
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6 Posts
Discussion Starter #1
Hi All,

After several mechanics had told me the only way to diagnose a new ‘whine’ from the engine bay was to start wrenching, I thought there had to be a better way.
An engine bay is a very busy and noisy place, making it difficult to work out exactly what is the cause of the sound
As an audio engineer/programmer I already had a ’Sound Recording’ program on my phone, so I recorded 4 samples (all from front of engine):
top left, top middle, top right, lower mid

The results are as follows.
Using the free software Audacity:
car-engine-bay-left-middle-right-right-bottom-audacity.png


As you can see, the ‘loudest’ section is the one recorded from ‘lower-mid’ - but not exact enough for a diagnosis.

So I loaded it into one of my pro music programs to show a lot more detail:
car-engine-bay-left-middle-right-right-bottom-iZotopeRX7.png


As you can see, the ‘lower mid’ section is way louder in the oustanding frequencies, so it had to be that location - which just happens to be the A/C pulley.

A/C pulley replaced by best mechanic on the Northern Beaches of NSW ([email protected]) and car fixed.

Also note that this problem caused not just a whine from the engine bay, but erratic RPM's on cold start.
Also fixed.
 

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Registered
1995 EZ30 Coupe
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799 Posts
Also note that this problem caused not just a whine from the engine bay, but erratic RPM's on cold start.
Also fixed.
Huh, that's interesting. Can you soon the old pulley by hand?

Great work with the audio stuff!
 

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Registered
1995 EZ30 Coupe
Joined
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799 Posts
I swear I typed spin not soon! But you got it...
 
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