Detonation at idle? Or coolant lines making noise?
 

When my car has been off for a 5-7 minutes and everything is heatsoaked, I sometimes hear a noise that sounds like a cavitating pump (like tiny pebbles going through the motor). It happens at a greater pace when stepping on the throttle a bit, but goes away by the time I pop the hood and try to listen. I highly doubt it's detonation, but is it something I should worry about? With the way my turbo sits the supply water line is the highest point in the system and I've heard water flashing over in there after the car is off. I'm thinking it's related. Any thoughts?

I'm running a DIYPNP with idle timing at 15 degrees, 13.2 afr

With those settings and no load there is no way you would be detonating unless something was messed up in a major way.

Check the static timing at 10*

I did that and got it right. I haven't flashed any firmware since doing that so It should be fine. I haven't heard any knock at WOT or just cruising either.

Now go confirm the balancer didn't slip like it has on my Miatas.

Det is almost impossible at idle.The load is just too small.

Do you have an fpr? Is it mounted to the fire wall? Do you have a man sized fuel pump? If so, its the fuel rushing through the fpr.

Do you have more info on this? Answer to all these questions is YES and it makes some cool noise. Perhaps I should un-mount from firewall as I mostly hear it inside the car...

Basically On my setup I can hear the fuel flowing through the regulator. I have the AEM regulator and I'm sure if I went to the larger orifice I wouldnt hear it. Start the car up and bust out the mechanics stethoscope or just a long screw driver and see if the noise is coming from the regulator.

I know that it is the fpr (Vortech), I am just not sure that I am supposed to hear all the transformer movie noises it is making. Perhaps I should make a video.

Miata Transformer Sounds - YouTube

When I tap the throttle transformer sounds appear!! :rofl:

???