johnchabin

iTrader: (2)

Before I take off my Extention Manifold (again), I'd appreciate a second opinion...

I have what I thought was a Turbo Precontrol problem (low transition) which was coupled with a slow build of boost. I found no obvious boost leaks and the precontrol Solenoid/Actuator/hoses tested ok. The Turbo Precontrol Valve shuts tight with the 1/2 hole pulled over the pin blah blah blah...

I decided it may be a Turbo Control problem with a lazy actuator. I tested both the vacuum and pressure sides of the actuator by putting a pressure & vacuum hand pump on the top of the appropriate metal lines that head down to the actuator. No leaks & both sides move the actuator.

I went the other way and tested to see the pressure tank holds pressure. It does in the short term, anyway. This tested the hoses from the check valve to the closed Turbo Control solenoid valve.

Then a road test with a T into one of the Pressure Tank hoses. Started at zero (obviously, I had disconnected it) and built up boost as boost increased on the first turbo. I let off producing vacuum (19 lbs) to see if the check valve really was holding (it was). Finally, the WOT run from about 2800 rpm up. Boost on turbo one was 11 or so, then at transition I got the big drop (6) with the Pressure Tank dropping as well, then the slow build of boost back to 11 in both the manifold and the pressure tank.

So I think I have a bad hose on the actuator side of the Turbo Control solenoid. Once I pass 4500 rpm, the solenoid opens up, leaking boost out the hose and never providing pressure to the Turbo Control actuator. The actuator eventually gets there on vacuum, the two turbos eventually build enough boost to overcome the leaking hose, and I slowly build back to 11 psi.

More info: if I leave pressure in the Pressure Tank (say 11 lbs), I lose it all when I start the car. Also, if I leave pressure in the Pressure Tank for a number of hours with the car off, it SLOWLY bleeds away.

Any comments or suggestions before I remove the manifold?

Also, how can I turn on the solenoid (through the wiring harness?) so I can try pumping up the pressure tank all the way to the actuator to check for leaks without pulling the manifold?

Sorry for the length, but I think all the info is significant (to me, anyway).

johnchabin

iTrader: (2)

I am impatient...

johnchabin

iTrader: (2)

Nobody?

TYSON

I'm no expert, but it kind of sounds like you have 2 seperate problems there. The slow leak with the solenoid closed, and your transition problem. If it was only a hose on the actuator side, you wouldn't get the slow leak with the engine off. If it was just a slow leak from the tank, you wouldn't have the big transition drop.
The check valve should not allow pressure to drop in the pressure tank. Air in the tank has nowhere to go other than to the solenoid and actuator. I would check the hoses on this circuit and replace that check valve. It's and expensive little valve, about $25 but you can change it without taking off the manifold.

TYSON

You can turn on the solenoid. Starting page F-84 of your service manual.

Flybye

If you want to pressure test and vacuum test the various components of the turbo system, I highly recommend buying one of these:
http://www.mityvac.com/


Purchase the model that inlcudes pressure and vacuum pump and it also has a vacuum/pressure gauge. The only true way to test solenoids, actuators, and one way check valves is with one of these. These guys should NEVER leak any air.

Has your FD always transitioned at 6psi or did it start recently?

johnchabin

iTrader: (2)

TYSON: I don't own a DT-S1000 (page ST-11 and F-86) and I'm sure I couldn't afford one if I could get one from Mazda. I need a different way of turning on the solenoids. I will probably do it at the ECU harness unless someone had a better way. I want to turn them on before removing the Extension Manifold (I realize I can apply voltage to a solenoid after removal). Problem is I can't check the hose on the actuator side of the solenoid with my Mity-Vac, as the solenoid is off and open to atmosphere on the actuator side.

Flybye: I have the Mity-Vac and it's what I used to determine the above. The gauge is only for vacuum, but there is a pressure port. I use my coffee-can test gauge for the pressure side.

My FD has had transition issues since I had a local Mazda shop do the hose job. I have found numerous problems (mostly small holes in different hoses and pinched hoses) since I had this done. I had a shop do the job because I thought it would save me time. I will probably have to redo it now.

spooledUP7

John,
It sounds as though your mazda dealer miss- routed your turbo control solenoid hoses (pressure side) and or solenoid harness. Other solenoids that turn on when you start the car are:
(as shown in page F-10) A, C, F, and G.


Does the pressure escape when you turn the key on, or does it leak slowly when you turn the car on?

johnchabin

iTrader: (2)

Perhaps you are right. Maybe F is most likely being next door to Turbo Control (Pressure Side). I don't think I can avoid pulling the manifold...

Thanks for all the help, guys.

The pressure drops immediately to 0 when starting, not just with the key on.

It leaks VERY slowly when just sitting (over a period of hours).

johnchabin

iTrader: (2)

UPDATE: I have a bad check valve leading to the Pressure Chamber. It leaks slowly (10 lbs is gone in about 10 minutes).

Not sure about the fast leak in the pressure side at transition. Haven't taken the Extension Manifold off yet. All hoses to the TCA are OK, but I can't check the one on the TCA side of the Turbo Control Solenoid Valve (pressure) without turning the solenoid ON.

Anyone know how to turn on a solenoid without removing the Extension Manifold? (like through the wiring harness?)