paperjam

I had a boost issue where sometimes the turbos (primary and secondary) would come on sometimes not. When I wouldn't get boost and I would release throttle the air pump make this terrible winding down sound (not the BOV). When I would get boost I wouldn't hear this sound at all. I have a microtech ECU also and the air pump is unplugged (don't know the full details but that's the why the mechanic did it). To cut a long story short the "sometimes boost" issue was driving me nuts and I was considering a single turbo conversion. Apparently it will cost almost as much to diagnose the issue and fix it than to do a single turbo?

Anyway, I was cruising through the country side, nothing different, no changes to the car, no services or anything and I got the "sometimes boost" and "sometimes not" issue on the way there like usual. Took a winding ride (about 3 kms) down to a dam, seemed to get good boost. On the way back hammered it through the curves, got boost everytime. All the way home (highway), full boost everytime, even in 1st gear which _never happens. Was thinking this won't last. Later on that night, full boost. On the way home, full boost. This morning took it for a drive, started cold, full boost. Woah, did it fix itself??!

Anyone know how I went from having the problem to it being virtually cleared now? 95% of the time now get boost instead of around 30-40%, and when I don't get boost now the air pump makes the sound _with the BOV not a delayed second after. Did something clear out? I had the vacuum hoses changed over a year ago but that didn't fix it. What could have magically fixed it? I hope it doesn't come back.

Mahjik

iTrader: (1)

Sounds like you have an issue with the TCA (Turbo Control Actuator). It's controlled by two solenoids which supply pressure and vacuum. Both are required to move the actuator for proper turbo system control.

I would start by checking those first. Depending on the year of your car, some of the US based troubleshooting tips may or may not be of use to you.

paperjam

Thankyou for the response. It is a series 7 (97 model). It's a funny problem because it would come and go only it would be more on the no boost side. Now it seems it's fixed and on it's own.

I found these pages -

http://www.autosportracetech.com/RX-...leshooting.htm
http://www.fd3s.net/boost_problems.html

Could a constant drive with boost and WOT somehow 'flick a switch' to make it work as it should? Just trying to find out what's changed to make it good. When I take it in I'll get them to check those things first. Could a boost controller help also?

paperjam

After a week of having full boost at all times and figuring out the best revs for gear changes with max acceleration the old boost issue came back and without any reason I can tell why. It's like something is blocking air flow.

If I replace the Turbo Control Actuator and the solenoids that connect to it is that something worthwhile doing? I still get boost but it is intermittent. The air pump is making a whooping sound again when I don't get boost. What role does the air pump have when I'm not getting boost and making this sound?

Mahjik

iTrader: (1)

Check this thread and see if your issue is similar:

https://www.rx7club.com/3rd-gen-archives-73/weird-boost-issue-685269/

paperjam

Thanks mahjik. BTW, I have a microtech LT8.

paperjam

Just wanted to post the solution to the problem I was having in the event someone finds it useful....

Before the boost issue I had a hesitation issue a long time ago and ended up getting a microtech to fix it. I got fed up not having my car for so long that apparently that would fix the problem (albeit an expensive one). I still had the boost issue after the microtech but the hesitation was gone. After about 1.5 years took my car somewhere else (Rotary Motorsport, Brisbane), Ben fixed it in about 3 hours. Hope I remembered this right, found one of the valves wasn't getting enough ohms and was likely causing the stock ECU to go crazy (hesitating). Also found a broken hose under the manifold that was replaced. I probably didn't need a microtech either and apparently not recommended for a twin setup? Anyway, boost issue fixed and cause of the hesitation discovered. Been driving well for more than a week. Couldn't be more happier or thank Ben enough.