The car is a turbo Miata with megasquirt.
The turbo is a TD04H.
I've got no boost. The car has been sitting for a while.
I'm reading a reasonably healthy 18 in-Hg of vacuum at idle. If I no-load rev it, it will move to about 5 in-Hg of vacuum.
If I rev it under load, it will max at 0. This is a standing still load- I have not launched it on the street. With the brakes applied and car strapped down, I cannot develop boost at any rpm.
OK, so I started searching. I found significant leaks at virtually every joint in the piping. Fixed them. No improvement.
Turbo spins freely. No play in the shaft, no grinding noises. No scraping, or metal shavings.
Boost gauge works. I disconnected the tubing, pressurized the line, and read boost.
I disconnected the piping from the turbo, and held my hand over the outlet while running. I could feel air flowing, but not at significant pressure. I could seal it with my hand, including when revving.
So, I am thinking waste gate. I can move the actuator rod with some resistance, but I am hearing a lot of rattling inside the housing. I am waiting for the car to cool down to pull apart the exhaust, but I am betting on the waste gate being broken/ loose/ stuck open/ etc.
Any other thoughts? Any other ideas on diagnostics?
I know I should launch it on the street under a real load, but shouldn't I be able to create SOME boost standing still?