I am a new member from Escondido, California, looking for a bit of help from the experts. I am a stock 5-speed 1994 FD owner since new (see pic below) with about 68000 miles. I am a fair "backyard" mechanic and I have been studying the complex details of the sequential turbo system because of a new boost problem. I wanted to give fixing it a shot before taking it to someone so if anyone here recognizes these symptoms I'd greatly appreciate a hint of perhaps where to look first. Here they are:

When I first start the car I always bring it to operating temp before driving it. Out of the garage, it runs perfectly - boost in primary and secondary phases in every gear just as it should be (at least it feels that way!). After about 7-10 minutes of driving, the boost suddenly becomes intermittent. Specifically, on some gears there is boost and on some there isn't any at all. I seem to often get boost in first and lose it in second. It often comes back in third gear. Other times I have it in second gear. Regardless, it just about never has boost in sequential gear changes.

Also, any time I am in a gear where there is no boost, after I let up the gas pedal for the next shift I can clearly hear from the engine area a sound of a rush of air perhaps releasing out of something. Kind of a "whoaaaag" that lasts a few seconds. Next shift there is typically boost again. Was that my lost boost pressure?

Heat build-up problem? Waste gate not closing? Actuator sticking? Solenoid? Vacuum? Check valve? When it works, it works well and probably half of all accelerating gear shifts have boost, and when it doesn't, well, it just doesn't and I get the noise after I let up on the gas.

Like I said, any help here would be most appreciated! I am a professional guitarist and singer (Google me if you like) and have helped countless folks with free lessons and consultations over the years. I guess I'm hoping to get a little of that "paying forward" back from the fine and knowledgeable RX-7 community here.

Thanks so much!
-Alan Iglesias

 

welcome to the board, Alan.

for your problem, you should check the boost solenoids and wastegate controls you can locate. maybe take a look at the bypass/blow-off valve too, for good measure.

here's a link to a thread that may be helpful: https://www.rx7club.com/3rd-generati...-turbo-765515/

and here's a link to the search results (in case any other threads can help): https://www.google.com/search?q=rx7+...hrome&ie=UTF-8

it might do you some good to get a copy of the FSM. you can download one from: Foxed.ca

you will need it because my guess is you may need to go through and replace all the vacuum hose that control the turbos.

 

Thanks so much, Diabolical, for your welcome and reply! Everything you say makes sense and thanks for the links, too. Yes, I have DLed all the relevant manuals.

Yeah, I know it's likely that it's time for the silicone vacuum hoses. I do everything I can to keep the heat down under the hood, but you know how hot it gets in there!

Also, if anyone knows a good FD mechanic in Southern California that you trust (mine passed away), please let me know!

Thanks again for everything and I'll keep the thread updated with anything that happens.

-Alan

 

The "whoaag" sounds like the Charge Control Valve is open when it shouldn't be. This allows the Primary turbo's output to go backwards through the Y-pipe and out of the Secondary Turbo's inlet. Anyway, a Vacuum Hose job doesn't have to be "complicated" or "difficult". It can be done as a DIY if you take it one hose at a time. Also, to help keep things organized, I'd suggest using a different color of silicone hose so you can tell what you've already done.

If you're stuck, Mazdatrix is probably the closest "expert" despite being 90 miles away. Racing Beat is about the same distance.

 

Fantastic stuff, Akagis - thanks so much! First thing I'll do is check the CCV to see if it is sticking or not and if the vacuum is in the right place at the right time.

Also, thanks for the mechanic referrals - I really appreciate that!

You guys are great!

-Alan