I'm at my wits end with my 99 JDM FD, it has never boosted right since I've owned the car. The secondary turbo was not operating initially so I stripped the black box & found 2 dead solenoids. Instead of replacing these I replaced the whole black box with new from Mazda and at the same time replaced all vacuum hoses & one way valves. After this the primary turbo stopped working and secondary started working (5psi max up to 4,500 and then full boost after). After taking the car for a long spin it reverted back to the previous of full boost on primary & loses all boost over 4,500 making a strange "wooo" noise when you let off.

So far I have:
- Checked all hose connections against diagrams
- Checked vacuum & pressure holding in tanks over night
- Tested actuators operating under vacuum/pressure
- Tested pressure relief valve opening under vacuum
- Tested operation & resistance of green solenoids under UIM & swapped around just in case
- Checked CCA pulling in on start-up and working after multiple KOKOs
- Cable-tied CCA closed (when only secondary was working, still no primary)

I have videos of both problems, just need to figure out how to put them up here.

I'm lost now as to what else to do. Any advice?

 

Video of primary not operating (up to last night):
https://www.dropbox.com/s/89n2nrajbv...03131.mp4?dl=0

Video of secondary not operating (started again last night):
https://www.dropbox.com/s/1ib8xo71en...13100.mp4?dl=0


Sorry quality is pretty bad but you get the idea...

 

Damn that is a shame. I've got no advice apart from double checking everything again. There are some guides such as Troubleshooting but I guess you've seen that.
I know of someone who spent $3k at multiple workshops with similar issues. No luck until they took it to a Mazda dealer, who found two hoses incorrectly fitted.
The twins are great when they work properly!

 

Wow, a Mazda dealer that could trouble shoot a FD, I'm impressed!

The whooo is probably a BOV venting to the atmosphere. Is your intake stock?

It sounds like you have checked everything. Like PeloNZ stated, recheck everything. I did mine and had a check valve in backwards. Also check the new solenoid valves you bought. They may be bad, even new. And check all your solenoids hot as well as cold. I had some that checked ok cold but would not open hot. Here's a how to (for USDM)

https://www.rx7club.com/3rd-generati...-stuff-802060/

Good luck.

 

You can fix electrical problems with a hammer!

 

I had a similar problem with the primary not making boost and fixed it by replacing the turbo control solenoid.

 

Cheers buddy, have checked the turbo control solenoid and seems to be operating correctly. It's a brand new one inside the black box and the vacuum one attached to the LIM, I swapped for another & same.

Took another 2 videos earlier if it helps anyone

 

I hope this troubleshoot information helps:

Troubleshooting