I'm working on a '94. We are getting NO boost off of the Primary, and the full 10psi off of the secondary.

The vaccum lines were tripple checked, the check valves hold pressure/vacuum, ALL the solinoids are working properly, the wastegate is working properly, the charge control valve is working properly, we even replaced the turbos with a good set. WHAT THE HELL DO I CHECK NOW?!?!?!?!

Has ANYONE heard of NO PRIMARY, FULL SECONDARY BOOST? We are getting desperate here and have been on the phone with RP, Mazdatrix, etc.

Whoever figures this out is a Freakin Genius...

 

I thought the secondary would not come on unless the primary was making at least 8 lbs of boost?

Did you make sure there are still pills in the lines to the pre-control and wastegate actuators?

 

Check the integrity of your vacuum reserve tanks. On a manual shifter there are two tanks: one in front of the UIM and the second tucked in behind and below the power steering pump. If these are cracked or split you will lose the vacuum pressure reserve necessary to operate the turbo solenoids. Depending on which one is cracked it could affect the operation of the primary turbo. If your solenoids are working (meaning you tested them with a twelve volt charge and they switched air flow properly), then you must be having a vacuum leak problem somewhere. Either that or your lines are strung wrong. How about your wiring harness? Any problems with the integrity of the electrical flow to the solenoids?

 

this is true

 

Make sure your check valves are flowing in the proper direction.

 

Check the hose connections at the turbo precontrol and wastegate actuator nipples. If these connections are not clamped or ziptied, pressure will leak out of them when the motor and turbos get hot; the precontrol and/or wastegate actuators will not work properly. From your symptoms, your problem can be traced to the precontrol actuator (which controls the primary turbo's boost pressure up to the transition rpm). Also, check that your precontrol actuator arm is adjusted properly. If the precontrol "door" is slightly "ajar", it will leak boost prematurely. The arm should be adjusted such that the "door" is fully closed when the actuator is not "actuating".

Refer to pic in the link below to see where the turbo precontrol actuator hose nipple is.

http://www.autosportracetech.com/RX-...BigPicture.htm

 

I pressure/vacuum tested both chambers. I've checked the routing of the lines 3 times now. We replaced the turbo's and are getting the same boost pattern, so I know its not the wastegate or prespool actuators or doors. We tested all the solinoids with a 12 volt source, and they are all working properly. All the check valves have been vacuum tested and are facing the correct direction on the correct lines.

Heres the thing. If the wastegate is closed, the primary turbo MUST be spooling up. So the air from the compressor has to go to one of two places; either into the manifold creating boost, or through the CCV and out the secondary if the CCV is not working properly. The CCV *IS* working properly, I even zip tied it closed to make sure it wasn't bieng pushed open under pressure due to the diaphram bieng torn.

At one point we pinched off the wastegate so that it remained closed, and zip tied the CCV so that it remained closed. So thearetically the primary HAS to be spinning up and the compressed air HAS to be going into the manifold, and its NOT!!! I just don't get it.

 

What a bitch of a problem.

Have you done any "T-tests" to get any results like this:

http://www.geocities.com/laracers_vr_r1/boost_plots


Where in NM are you?

 

Not true...

I had the same problem. The hose leading to the actuator on the exhaust manifold was slit. I forget the name of the actuator, it is the only one that is on the exhaust manifold itself. The big silver one.

 

TCA=Turbo Control Actuator. This is the actuator that swings the "gate" inside the manifold to bring the secondary online. It is actuated with both boost and vacuum from opposite ends.



Kaotic Dan, are you sure the exhaust manifold itself is sound? I have heard of large cracks between the passages causing terrible problems. If you had a large manifold crack the primary may never spool as it's exhaust may spill through to the secondary side which is of course dumping its boost out the intake since the precontrol is open so you would read no boost. Once the TCA brings the secondary online and the precontrol door is shut you'd be seeing boost, but it would trick you into thinking the primary is dead since you would see no boost until after the precontrol door shuts. It would take a HUGE crack in the manifold to be capable of this though.

 

This has happened to me. After I re-installed my engine a couple months ago, everything was working fine. Then all of a suddon, I had no primary but the secondary came on full. It turned out that the c-clip for the waiste gate accuator door had broken. Double check that to make sure everthing is secure.

 

*EDIT*

I just changed "precontrol" to "charge relief". Sorry if I just thoroughly confused everyone but my previous post is incorrect. I meant to say charge control door.

*end of EDIT*

 

I will check that actuator and its lines out. Thanks!

 

Wouldn't you hear an exhaust leak like this, or is it just a crack within the manifold that lets air pass between the two turbo's but not out of the manifold itself?

 

Both are possibilities but as you pointed out if it was escaping entirely outside the manifold you would hear it.

 

Albuquerque. Our shop is Frisbee's Performance. I see your in Las Cruces? Your "T-tests" gave me some good ideas. I'm going to try them out...

 

I had that boost pattern once. It was 0 psi until 4500 RPM then 15 psi. The car ran like a dog, then a rocket!!

In my case it was the line going to the CCV was pinched, which was causing all the primary boost to vent out from the CRV through the open CCV. Double check your work.

Wade

 

Checked it, its working. I even zip tied it shut to make sure it wasn't opening under boost from a torn diaphram.

This problem just doesn't make sense to me...

 

There are 2 ways to get this boost pattern:
1) CCV stuck open - get someone to watch this get pulled in at ignition on.
2) TCA - this _should_ spring return to 'primary only' pop off the +'ve pressure hose, and use a hand pump to check the movement of the TCA arm.

I hate seeing people say you need 8psi on the primary for the secondary to work, it's not always true.

-pete

 

Mine is doing something similar. I can actually hear the exhaust note change. It becomes a deeper raspier tone and then I can go full throttle with almost 0 boost rise then the secondaries kick in full.

It only does it after a good amount of load too. I suspect heat related expansion which jives with the exh manifold theory.