Funny buzzing sound from idle control thingy ??

[wazman]

Hi all,

I need some help.
I had my adaptronic tuned the other day (only mod being a pod filter) and it all went fine and the car made an extra 7kw.......

But the next day after i drove the car around a bit there came a buzzing sound from the idle control thingy on the throttle body

I just unplugged the electric control valve or what ever it is...... Why dose it make this sound and how do i get rid of it ???

any help appreciated, thanks Waz

[Patty]

Idle Air Control valve?

If it's only there when you turn the ignition to ACC (or was it ON?) then mine's been doing it since I bought her 2 years back. It only stops buzzing when I pull the plug off it which then causes stalling.

Is it possible that it's always been there but you never noticed? Otherwise mine's stuffed like yours. Never had any problems with it though..

Might be good to get other NB8A's to comment.

[wazman]

no , mine has only started since i put in the adaptronic....... you can change the singnal strengh to it but if you turn it down enough so it dont make any noise then the car starts to hunt

So at the moment i start the car with it plugged in then un-plug it and it all runs fine

[ampz]

The buzzing is usually from too low a PWM (pulse width modulated) frequency used to drive the IAC (Idle Air Control) valve.
The Adaptronic has different values for this, unplugging the IAC will only give you the fastest idle available on the car, it doesn't solve the tuning discrepancy you're experiencing.

If the unit has been tuned by a shop, you really should be taking it back for them to adjust the settings to a more comfortable level. IIRC 785 Hz is whe're the NB's run their IAC valve best (it's around there, the exact frequency is escaping me, but not hugely important)...

Clicking or buzzing comes from too low a frequency, NB's hate anything under 500Hz and some are even comfortable around 1000Hz (but longevity of IAC id degraded at those frequencies).

If you want to tune it yourself, read up on the Adaptronic manual on how to tune your idle settings, this is a good guide but i would be holding the tuner to ransom over it, if you have time.

Also, chek your adaptronic plug in harness, to see if the right year model has been supplied for use with your car. For exapmle a 99-01 harness will function on a 02-05 NB, but soem wires are transposed. Same for the early 1.8s (94-95) have a couple of wires in different spots when compared to the 95-98s...

[wazman]

Thanks ampz, I'll take it back and get it changed..... we only did a quick tune as its going back for a final tune once the turbo is on.

Thanks for taking the time to write the explanation, at least i'll know what i'm telling him to fix when i go back.

cheers, waz