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Old 09-08-2010, 12:36 AM   #1
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Default Intake Hum Following install

So I just finished up installing my MS-1 I purchased from another member here, did the MAF deletion and all that stuff. Now I have this ( for lack of a better term) hum coming from my intake. Its loud enough that is hurts your ears and occurs at idle the loudest but dissipates the hight the RPMs are. I did figure out it is coming from the Idle air control unit and is magnified by the intake pipe ( Old school Rspeed intake). I am running the base map provided on the DIYautotune site until this weekend when I have a chance to actually do a bit of adjusting on the Dyno. had anyone ever experienced this before and is there a fix? BTW its a 1994 1.8 with header, intake and full exhaust. I am running tunerstudio if that matters.
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Old 09-08-2010, 12:53 AM   #2
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adjust idle stepper motor frequency
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Old 09-08-2010, 12:57 AM   #3
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I tried that and it didn't seem to help much, I guess I will dick around with it tomorrow when its not so late. Any other ideas?

Last edited by eraser; 09-08-2010 at 01:11 AM.
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Old 09-08-2010, 01:06 AM   #4
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Make sure your intake hardware is tight and not buzzing against anything.
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Old 09-08-2010, 01:11 AM   #5
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That was the first thing I check was all the hardware and misc stuff I had fiddled with. I am 100% sure its the IAC valve, I actually pulled it from the intake pipe and the sound became much more bearable ( intake was acting like a megaphone), but the noise is still present.
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Old 09-08-2010, 04:05 AM   #6
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Some buzzing is normal, I even had that with the stock ECU. To get it as low as possible, you need to run the valve at a frequency of 500Hz, using Jean's PWM multiplier board.

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Old 09-08-2010, 07:25 AM   #7
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I believe the NA has a slightly lower frequency than the NB, just under 400Hz IIRC.
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Old 09-08-2010, 05:59 PM   #8
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Got it fixed, kept playing with the frequency utility it went away, now it just idles high. Lol
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Old 09-08-2010, 06:12 PM   #9
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Dammit, had a smartass response all ready to go when I clicked on the thread and you've already fixed it.
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Old 09-08-2010, 07:18 PM   #10
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Quote:
Originally Posted by mgeoffriau View Post
Dammit, had a smartass response all ready to go when I clicked on the thread and you've already fixed it.
Glad I beat ya to it
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