Whistling sound from cold air intake

[FBD]

24 minutes ago, TobyB said:

These 3 bolts have the ability to make all sorts of noises if they're loose, too short, too long, or not sealing completely.

 

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Interesting, I shall check

 

[FBD]

I did a smoke test to test for any vacuum leaks, all good. I decided to pull out the throttle body and air intake plenum to see what might be causing the whistling sound (which by now was driving me nuts and distracting from the great driving experience of these cars!)

A number of causes, a couple I should have picked up on when I was putting it together!

First, the adaptor plate for the larger 325i TB, left the sides of the original mount slightly exposed, short work for the die grinder to rectify, next the TB itself had the unwanted ports neatly plugged, but on the inside of the TB there was plenty of  whistling opportunities! So I filled them with JB Weld then sanded smooth.

It could have been one or all of these things contributing but as I had it apart I did everything that looked like a potential issue.

Test drive successful, whistle gone! I put it on the dyno for a final Megasquirt tune and got 105HP at the rear wheels, hurrah!! 

 

Edited April 18, 2018 by FBD