Boost Problem Part 2
 

OK here are the symptons
a) Great boost until around 5k where I start to lose it and finally at 8k its nearly nothing.

b) when I shift, if I dont hold the gas (like the RPMs Up) it wont boost next gear.

Ideas anyone??
Just to mention I have the seq simplified system. In other words no emmisions.

mine is almost doing the same thing, sometimes it works fine and others there is no boost after 5k. I think its a Vac hose. Just gotta find it :(

How to find a vacuum leak: Borrow an air compressor, plug the turbo inlets (I used spray paint can tops). Put 10 psi or so in through a UIM nipple. Listen for the hiss.

Im not sure if its a vacuum leak since its possible that I may have put to long a hose or something. Where could I possibly get a plenum design splitted with like multiple nipples to aquire vacuum from the vacuum tank, I have a feeling thats what it is.

Sounds more like a vacuum line misrouting than a vacuum leak.

I think your CRV is stuck open. Either by vacuum hose misrouting or bad part.

My thoughts too.

CRV?

BTW Any chance of the pressure tank or vacuum tank being bad with these symptons?

CRV = Charge Relief Valve

It's unlikely. I can't recall anyone who has had an issue with bad pressure or vacuum chambers.

should check the CRV for looseness when under the circumstances of driving hard and during hot days.??

If you havnt done it yet.. vac job time :/ here comes the fun lol..

I already did the vac hoses with silicone, bu I did the simplification I triple checked my worked and everything seems correct. The seq simplification.

Purchase a vacuum pump and alligator clips and start doing manual actuation tests.

Many tests on what?? The actuators?? The Precontrol and Wastegate Control work (since the boost control is adjustable). What else should I check?

Check to make sure the charge control valve (CCV) that is the little butterfly flapper inside the y-pipe (the pipe that connects the output of the two turbos) moves when you apply vacuum to it, and returns smoothly when you remove vacuum to it's actuator. What the gurus are thinking is that for some reason the little butterfly is slowly closing as your rpms are increasing, which is choking off the secondary turbo boost OR that the secondary is not being added to the primary and the primary is simply running out of oomf at the upper rpms, which would happen if th eCCV isn't opening at all. The valve is normally closed until the engine reaches 4500 rpm AND there is at least 8lbs of boost from the primary, THEN a vacuum signal from the vacuum chamber is routed to the CCV actuator via it's appropriate solenoid. This allows the secondary turbo's boost to be combined with the primary for whoosh! If the vacuum chamber is leaking (or filled with oil), then it wont provide actuating signal to the CCV for long enough.

Have you gone to http://www.autosportracetech.com/RX-7/rx7stuff.htm
yet?

Ok this sounds very much like the cause, the lines or my vacuum chamber could be busted. But I beleieve that there are to many T's in the line to the vacuum tank.
BTW this is the design I used to try to stay seq* but get rid of sh*t

http://www.rx7turboturbo.com/robrobi...simplified.jpg
I really appreciate the input guys.

welcome to the club. i have the EXACT same symptoms and everything in my vacuum simplification seems fine also.

Two things.

a. Permanently open CRV (Charge Relief Valve).

OR

b. Permanently closed CCV (Charge Control Valve).

Very easy way to detect:

http://www.anodized.com/~clayne/fd3s/crvccv.jpg


Tee your boost gauge vacuum line with the red line.

This will show you boost at the secondary until the CCV opens, at which point you should see a slight dip and then boost again.

If you see nothing the entire time, then the CRV is open. Use a vacuum pump to test it. If tests good, then use alligator clips to hard wire the solenoid open and a vacuum pump on the red line (in the big routing) to test the vacuum path. If this is good, it is the solenoid or wiring to it.

If you see boost all of the time, then the CCV is not opening OR a boost leak exacerbated by increased CFM from the secondary turbo and should be fixed immediately.

Thanks I shall test both of them tommorow.
One last thing I want to fix, anyone know where I can get a plenum type connector with like 3 or 4 nipples sorta like the one that comes with the Profec B which has 3 nipples. Anyone?

Alright I put the boost gauge where the the red line is, I got the exact same readings I would get if I was at the manifold. Umm Its same thing, boost till 5 or 6k then drop in boost.

^

Alright guys, I need more tips, why woulnt I be getting boost on high rpm? I put the boost gauge where you stated and it acted exactly the same as if it were on the manifold.

on a side note, i got my secondary turbo problem fixed. i forgot to hook up a vacuum line to the intake manifold. i had "looped" a piece in between the spares and forgot to hook up the last one from the check valve. well thats the one that "Ts" into all the solenoids.

fatman if you do firgure it out let me know. I think im gonna take it to mazda because my check engine light flashes. I think mine is the CCV or a solenoid.

I have no idea whats going on Ice,
I connected the boost gauge just as Clayne directed, all I get are nearly the exact same readings as if I were on the manifold. Maybe it is CRV and I'll probably throw some duck tape on it. This way if it blows off I know its that for sure.