FD Boost issue.. please help
 

okay so I asked this same question last year, but here goes again,

I bought my 93 jdm rx7 and it would boost to .05 bar and them bog and jolt the car pretty hard, at first it was only under heavy load, then one day i started it up and it would boost fine almost to a full bar, I pulled the car out of storage a couple weeks ago and its doing the same thing. I thought it might be fuel cut but the check engine light doesnt come on and it will allow me to rev as high as I like (I have no experiance with rotary cars, Ive owned turbo'd toyotas all my life) I cant see it being any different between brands as far as fuel cut is concerned. so my next guess was bad by-pass valves I pulled the vacuum lines off and blocked them off but it still does the same thing. I honestly have no idea what it could be. so I turn to the experts on this site.. if anyone has any ideas on what it could be please let me know. I really appreciate it! as far as i know the engine is stock just a re-amemiya intercooler. other then that it looks pretty stock.

Thanks,

Enver.

Boost issues are a challenge to diagnose.

In the 3rd gen FAQ thread:
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/
Scroll down to the T section where you will find a link:
http://www.autosportracetech.com/RX-...erOverview.htm

Spend some time reading the troubleshooting procedures on there. The CEL won't illuminate on fuel cut. Also be sure that your boost gauge is accurate.

yeah i know it sucks. im going to put an hks ssqv on it and see if that helps.

Have you thought about making it non sequential?

No that won't help. Read the turbo troubleshooting link I mentioned. unless you enjoy pissing away money.

UPDATE!

after taking the car to RX7 Specialists here in calgary, they found my mid pipe was toast, and that a coupler wasnt connected properly, so $700 later, the car ran great!... for about 2days and now its doing the exact same thing! i took the couplers off and checked them for cracks there fine. so i put it all back together and took a video for you guys im hoping someone on here has had the same problem, rx7 specialists say the only thing they can do is put a power fc on it and hope that helps.. which really doesnt make much sence to me. im interested to hear what you all think!

http://www.youtube.com/watch?v=f2VwY9yha1s

Thanks,
Enver.

Its difficult to diagnose that kind of issue. You need to get under the hood with a Mityvac and the procedures in the link I posted and try and diagnose the issue.

Installing a PFC won't fix a problem with boost control.

It's unlikely that a PFC will help. I would be willing to bet the issue is with solenoids.

Is there any correlation between how hot the car is and boost issues?

I have the same problem from cold to running temp. Im really hoping its not a PFC. Im going to go back and look at it myself because rx7 specialists arent going to do anything they said all they can do is install that PFC and hope it works.

my fd does the same thing too, I think its either a clogged vac line or broken vac line. Or bad solenoids. My car hits 5 lbs of boost and cuts off and boggs and back fires. I havent gotten time to chase the issue but I have fixed twin turbo problems before like this and it is quite easy if you remember the diagram of the twin turbos. When I figure mine out I will post what I found but if your willing to take the challenge I would tell you to start at taking your UIM ( Upper intake manifold) off and looking at your vacc lines making sure they are all good and not cracked or brokem Then after that check your solenoids that activates the turbo systems. I would recommend looking at the vacc diagram and solenoid diagram so you know which ones to look at or test out. You can test the solenoids to see if they are giving the correct resistance. Look in the mazda rx7 book for resistance for the solenoids. Im sure the issue is some where under the UIM.

How did you fix this problem? I'm having the same issue with my rx7
 

Depending on how baked the engine bay has gotten, you could have a problem in the rats nest as well, Getting a tool that goes over the front of the turbo then you can hook compressed air to it, it will reveal a leak very easy, you can find tons of videos on this method on youtube.

Gus...
touturborx7 hasn't been on the forum since last September. The chances of an answer are slim. Try reading through this ---> Mazda RX-7 3rd Gen Stuff

Thanks you! I have replaced all the vacuum lines from the rats nest and tested all my solenoids but I'm still having this same boost problem.

There's a lot to go through and you need to be meticulous and double check everthing. Are you on the stock ECU, are the check valves in the right direction, are the hoses installed correctly, did you check your solenoids hot, have you checked your actuators (all of them), O2 sensor, MAP sensor, etc.

Bump Please engine cut under boost
 

touturborx7 since you're more active than the OP, can I ask what solved your issue? I'm also experiencing a bog at the same boost range. The car can rev all the way to redline in gear but as soon as it goes to the .4/.5 bar or 6psi it feels like a boost leak or fuel cut