Liehry

I recently got by FD rebuilt and ever since then the second on the twin turbos will not engage. I got the mechanics to look at it and they stated they could either turn it non-sequential (poor mans fix) or order new parts costing an arm and a leg (this the only way to get it sequential). Now I'm no rocket scientist but to me they're **** arsing about, something doesn't sound right.



So I'm after suggestions on getting it fixed (will eventually get a single turbo conversion but not just yet). I have the '93 service manual (is this generally good enough for maintenance?) and have read through it and gone through the hundreds of posts in this forum to gain a better understanding.



The boost kicks in around 2k at about 6-7 psi then drops off as the rpm increase past 5k until there is zero boost at redline. Also when punching gears boost drops off until I back off and get back on the gas. From what I've read the second turbo wont engage unless the primary is getting at least 8 psi.



I had a chance to look over most of the lines for potential gas leaks with not much luck. I did find what looked like an actuator just under the metal air pipe that goes from the top of the turbo cluster to the intercooler that was partially unplugged with hoses nearby which I reconnected. Looking at the pressure chamber on top of the engine the hoses were quite loose and the hoses didn't seem to be doing anything, but I zip tied them to keep them secured.



If anyone could give me some guidance as to what would be a good next step it would be greatly appreciated. I'm thinking of getting new hoses and doing the whole lot again to try and find the leak and replacing the gaskets.

amp

first thing to check is the ypipe... if youre still rocking the stock ypipe with the coupler.. that has a tendencey over time to rupture

it wont be obvious but a crack on that coupler will limit the boost you can generate out of the primary..

alos check the double throtle control.. this is the actutator by the throttle body.. if this isnt working.. it will limit your boost to 5-6psi...

if i were you... id go ahead and turn it nonseq.. easier to maintain and less costly....

leetfade

The non-sequential isn't as tough as you might think. You would be surprised once you got into it how bad the lines / solenoids probably are anyway. They get very brittle...



I started with just trying to correct a couple of things and things just kept snapping! Mind you, this car only has 78k miles so it's low for the year (93).



One thing you can check relatively easily are the actuator arms for the sequential turbo set-up. I found one of mine was not hooked up so it would not open the flapper to the secondary turbo. Just get under the car and look up at the twin turbos. There is an actuator to the front of the car and it has an arm connecting to that flapper near the secondary turbo. If that's not hooked up it could stay closed. Also, if the vacuum line to that actuator is not hooked up, cracked, or busted, it may not get enough vacuum to open it.



If you decide to go non-sequential, this is a very helpful link! http://www.rotaryresurrection.com/3r...ov_nonseq.html

Liehry

Great info lads, especially the how to link for non-sequential, looks a **** load easier with pictures to go off.



I've had some progress getting the initial boost up, which in turn has changed the boost pattern slightly.



When rolling on the throttle in any gear boost moves smoothly up to 10 psi until 4.5k RPM, then it drops right off. Now the weird thing (for me anyways) but possibly very helpful in finding the problem, is that when I change gears without waiting 5 or so seconds before pushing the gas I got about 2 psi through the entire range. But the thing is, when I change gears or drop the throttle I hear a very load strange whistle type noise (sounds like the pressure is getting caught up in the wastegate and shooting out, only because my mates skyline's BOV or WG makes a simmilar sound).



I did check the 2 long actuator arms linked to from the primary to secondary turbo, they both moved under pressure as per the service manual.



Just another quick question, the 2 solenoids at the front of the engine on top, I have 3 plugs, 2 marked, 1 unmarked, does it matter which goes where? At the moment the unmarked is on the left, and a marked on the right. I haven't moved anything around since looking at the engine, but I didn't take notes on what went where prior to getting the rebuild.



Thanks again lads, was a bit iffy at working on the car at first, but now I'm more than happy getting my hands dirty

leetfade

It does matter as one is the wastegate actuator and one is the turbo pre-control.



http://www.turborx7.com/images/Techn...e_diagram2.jpg



Are you referring to the vacuum lines on them or the actual ECU plugs? Either way, it would matter.

azeknightz

Look into this as I've developed an aftermarket seq system that work MUCH better and more reliable than stock seq system.



Check them out here: http://www.rx7club.com/showthread.php?t=966011



I am currently trying to gather more people on a GB.



The GB can be found in this GB section or here : http://www.rx7club.com/showthread.php?t=968956



This will fix most of your seq problem and boost will be much more smooth and should be "quicker". It is also highly recommended for any BNR twins. As these solenoids can handle up to 100psi where stockers are made for around 14 PSI max!



-AzEKnightz

Liehry

Well I've been away for a while but had a chance to try and study on the mechanics and theory of how the twins work. Got home and disabled the Actuator Charge Control so that only the primary turbo is engaged (working off the theory of getting the correct boost here and then work up to the secondary). With some refitting of hoses I now have a solid 8psi boost right through the entire rev range. So I am pretty happy how it runs now to be honest and considering that with the secondary i would only be pushing another 2psi of boost, I have a question. Would it be easier to continue running the single and doing a quick porting of the wastegate to get that extra kick? I have reconnected the second and it seems I have a massive leak somewhere, maxing out on 5-6psi and no secondary boost (just runs like shyt). Might just keep the single setup and get an aftermarket single turbo conversion put in at a later date when my finances are a bit better.