VE Anomaly
 

My VEs under boost show an interesting anomaly. It seems that between 4200rpm and 4400rpm the VE is lower than in the areas around it. Of course I don't have a data-point at 4300rpm in my VE table, so tuning it out with my current setup is not really possible. I have data points in my VE table at 4100rpm and 4600rpm.
This leads to a rather funky looking VE table:
https://www.miataturbo.net/attachmen...ine=1377872347
And I still get a dip in AFRs:
https://www.miataturbo.net/attachmen...ine=1377872347
I can run under boost all day long and get the exact same result. Virtual Dyno really shows a beautiful overlay.

I know I can tune it out by changing my rpm-scaling. That's not the question here.

But does anybody else see this? Is it just my car, and if so, is there something wrong with it? Also Virtual Dyno reports 185hp at 12psi. I'm running an old T28, but I still think there should be more hp from 1.8l at 12psi.

Year/mods/other info?

Mine ('96) has a high plateau through that region with a dip on both sides but no dip in the middle, but a VICS/VVT or some other intake gadgetry could conceivably cause something like that.

Details:
- 95 bottom end
- 99 head with +1mm valves
- VICS working and controlled by stock ECU (I believe it switches around 3000rpm)
- ancient FMII setup

why are you switching vics at 3000rpm?

and why would a stock ecu be switching it there if youre running MS?

I'm not switching VICS- I thought that's where the stock ECU switches it
Because lazy

so you're running parallel?

Yupp. Need to pass stupid emissions. MS3(X) is running spark, fuel and controls boost. Stock ECU takes care of idle, AC, VICS, EGR...

How does stock ECU control idle when the MS is controlling spark and fuel at idle?

Sorry- stock ECU is just controlling the idle valve.

So VICS switches around 5,250rpm. Some say 5,500. No difference- it's not the VICS messing with my AFRs at 4300rpm.
Anybody else see this behavior?

some other magical helmholtz phenomena?