Good day gents, my Foz has suddenly been making an irregular burping burbling noise in the engine bay, when I had a closer look it seems that the IACV is letting irregular bursts of air through the return to the inlet pipe, the presence of the stock air filter box seems to amplify the noise by resonating.
I'd been worrying that the inlet valves have been leaking and causing the noise, but the RPM stays rock solid throughout all of this, and so does the manifold vacuum, also I noticed that it does not do this once the throttle is revved at all, and only when it is at 700-750rpm idling. So i'm sure its the IACV's fault, but what is it? I've never read of a IACV issue that caused a noise such as this. Perormance isn't affected at all, the only other 'event' that has happened to the engine in this timeframe is the stock radiator blowing, which I caught early without running the car any distance, shortly after the rad replacement and resealing the cam covers, this noise started, any ideas?