Hi, so I've had my S6 FD (US) for about 2 years now) pretty much ever since I got the car I've had issues with my secondary turbo. I've been researching things and checking things for quite a while now with no luck. So pretty much where I'm at right now, my secondary turbocharger only works if it's under 20 degrees Fahrenheit or above 20 degrees for about 15 minutes. After that right at 4500rpms it makes an almost fluttering sound and my boost bounces from 4-5psi (usually 13psi) and at about 7,000rpm the secondary will kick back on and boost an even 9psi until redline. What I'm wondering is if there is any sort of temp sensor that is limiting my car? I've got Greddy intakes, Greddy hard intercooler pipes, tanabe catback exhaust, fluidyne radiator and silicone vacuum lines. Also have CWEST aero kit and vented hood. Engine was rebuilt by Mazda 17,000 miles ago. Sorry if I posted in the wrong section this is my first time on fourms.

 

I'm not sure I understand your symptoms vs. temperature. But you shouldn't be boosting AT ALL until the engine is at full operating temperature.
Your car does monitor intake air temperature, but afaik, it can't restrict boost. I would more suspect a solenoid or a sticky actuator.

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

A couple other links that might help, just in case you haven't seen them....

Turbocharger Overview
https://www.rx7club.com/3rd-generati...tified-841821/

As for the fluttering sound, seems like there are different possibilities...BOV or a solenoid issue. Search in the 3rd Gen. Specific section using terms like "flutter" in titles only and see if anything relates to what you have.

 

probably the typical ripped intercooler hoses, once they soften up with heat then you will lose boost through the tear.

 

Sorry what I ment is once at operating temp I've only got 10-15 minutes before it starts acting up. I've checked most of my hoses I can get to and a couple of actuators. Now that I have my Toyota 4Runner back I'm just going to pull the turbos and check everything as I go. I'll check more into those links. Thank you

 

Have your turbo precontrol and wastegate solenoids been checked? And have they been checked hot? A lot of times they will work cold, but not hot. There's a how to posted on the site

 

I've checked some of the easier ones to get to up top. Going to tear into it here soon. How would you recommend I check those by the way?

 

I would check solenoids E,F,H,I,J






How To...

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

 

I've gotten most of the rats nest exposed. I've checked everything up top and everything has passed their tests. (Thank you for that link btw, that is pure gold). The previous owner redid all of the vacuum lines with nice silicone line about 17,000 miles ago (about 10 years ago). Most of the silicone lines are tearing when I pull them off and the zip ties that are fastened to them are just shattering into pieces. So I defiently suspect a heat issue. I'll make more progress tomorrow but thank you for all the advice so far. I'll keep you all updated

 

There is always a heat issue with the FD. Especially those still sporting the original twins...like mine. The zip-ties get brittle but unless disturbed, they hold just find. And while the silicone will tolerate the heat MUCH better than the OEM rubber lines ever did, they will tear if you're not careful. I've had the same problem when doing occasional work. Can't remember the source off-hand, but some use viton hoses which reportedly are like the best of both worlds.
Underhood heat can be mitigated by a few things. If you're ever able, deleting emissions. It seems to 'unpack" the engine bay and allows a little better air flow IMO. It also reduces those vacuum hoses and solenoids by about half. But mostly wrapping or heat coating your downpipe. And when you pull into the garage you get in the habit of popping the hood.

 

Normal zip ties won't hold up to the heat. You really only need ties on the pressure lines, not the vacuum lines (if they are good and snug). McMaster Carr sells heat tolerant ties, but they're pricey. Make sure you also check your actuators (turbo, WG, & pre-control)