jaj1

I am trying to diagnose a boost problem I am having.
Some help would be greatly appreciated.

Mods are catback, downpipe, lightened flywheel, and new silicon hoses.
Turbos are not making any strange noises or leaking any oil.

My turbos seem to work fine in 3rd and 4th gear 10-8-10, actually
11-8-11.
The problem is in 1st and 2nd gears. In first gear the boost pattern
is about 6lbs and no transition it just stays at 6 lbs until redline.
In second gear the boost pattern is sometimes 10-6-6 and sometimes
10-6-10 or 11-6-11. This seems to change according to how low of rpm you
start off from. The lower rpm you start off from the more likely secondary
boost of 10 or 11 will be achieved.

What I have done so far is checked the one way check valve that
is located between the firewall and the UIM with a simple blow test
and it seemed to be fine. I could blow air one way but not the other.

Today I took a look at the Charge Control Actuator and performed this test
from DVanditmare website.
http://www.autosportracetech.com/RX-...leshooting.htm
"A simple test for the Charge Control Actuator is to start the engine and let it idle, the actuator rod will be pulled in. Stop the engine and remove the hose from Chamber A and the actuator rod will be out."
When I start the engine the actuator is pulled in but as soon as I shut the engine
off the actuator arm moves out. I do not have to unplug the hose on the actuator
from chamber A for the arm to move out. I am thinking that this is an indication
of a vacum leak and an inability to hold vacum. The engine at idle develops 17 inHg
of vacum.

I am hoping that some of the turbo experts here would have some suggestions
on how to proceed.

TIA

jaj1

Mahjik

iTrader: (1)

Did you read this section?

"The Turbo Control Solenoid / Actuator is one of the more complicated actuators as it requires both vacuum and pressure to operate properly. This actuator is controlled by two solenoids, (both are wired together to the one ECU output) one solenoid applies pressure to one side of the actuator and the other applies vacuum to the other side of the actuator. With pressure on one side and a vacuum on the other side of the actuator, the speed of the actuator is improved. A typical problem is loss of Secondary boost in 1st or 2nd gear at 4,500 RPM, but reliable operation in other gears. This points to one side of the Turbo Control Actuator not getting it's pressure/vacuum, so it will still operate but not quickly enough."

wrankin

verify the check valve that feeds the pressure tank (the black tank on top in front of the UIM) is pointed in the right direction (blows towards the tank).

-bill

jaj1

Wrankin, thanks for your reply.
I just to a look at the check valve in the hose that goes to the pressure chamber
and the arrow is pointing toward the pressure chamber. the check valve is brown
in color. Also if I start the engine and then shut it off amd remove that hose from
the pressure chamber I hear air escaping.
thanks again for your thoughts bill.

jaj1

jaj1

Thanks for the reply Mahjik.

When I started my adventure in rx7 seq turbo troubleshooting I read that section
of dvanditmars troubleshooting guide and I agree with you the symptoms seem to fit.

What is confusing me is the turbos don't pass some of his other checks.
As an example under his "Primary Turbo" section He mentions the "Charge Control Solenoid /
Actuator / Valve and the "simple test for the Charge Control Actuator" my actuator fails that test. The actuator rod immediatly after shutting the engine off is released out. I do not
have to remove the hose from "Chamber A".

Also, I want to make as sure as possible that I have eliminated as many other possible causes
before having to remove the UIM/Extension Manifold.
Mahjik, if I have to replace the Turbo Control Solenoids and remove the UIM can you tell me
if I can replace the TCS that is on the selonoid rack with out removing the rats nest itself?

Your input is appreciated.

Thanks

jaj1

Mahjik

iTrader: (1)

There are two Turbo Control solenoids. One is on the rack, one is on the ACV. The one on the rack will be difficult to replace without removing the rack, but not impossible.

Yes, you should test everything. However the Charge Control shouldn't effect your secondary boost (just primary) so you may have more than one problem happening.

jaj1

Mahjik,

Do you have any ideas as to why my Charge Control Actuator is failing the test?
Isn't that a sign of vacum not holding. Is it possible a bad Turbo Control Selonoid
would allow the vacum to leak off?
Is there a way to test to see if my vacum system can hold vacum?

Sorry for all the questions.

Thanks for your help

jaj1

jaj1

Anybody, any other ideas on my boost problem and is there a test to see if the vacum
system is leaking?

Thanks

jaj1

Howard Coleman

iTrader: (6)

before you start tearing things apart.... verify that you are getting the two proper signals at 4500 rpm at the charge control flapper valve. tap into the pressure and vacuum side of the lines to the door on the Y pipe and go for a drive.

you should read vacuum on one side and pressure on the other.

at 4500 the pressure should drop to zero and the vaccum should go to zero.

my bet is one event isn't happening.

then you have it made. trace the curcuit back on the problem side. it will be a leaky hose or a bad one way valve or a one way valve pointing in the wrong direction (they point differently as one is vac and one pres) last on the probability list will be a bad solenoid or a disconnected solenoid.

let us know what you find. now go buy a press/vacuum gauge and a length of hosing.

good luck,

howard coleman

jaj1

Howard, thanks for your suggestions. I was wondering if you or someone
else could answer a couple of questions for me?

If I start the engine and then shut it off and then remove the hose at the
vacum chamber should I hear air rushing in to fill the vacum inside the chamber?

Also which one way chack valves are associated with vacum?
Are there more than the one located between the UIM and the firewall?

Thanks

jaj1

amp

iTrader: (50)

im havin similar issues jaj1 with the charge control actuator..
although mine is no movement at all with the actuator rod at idle and off...

jaj1

Amp, your actuator rod should be in with the engine running,
and from what I am learning should stay in even if the engine
is turned off. What is happening with mine is as soon as I shut the engine off
the actuator rod moves out. I am not holding vacum in the system, I must
have a leak somewhere.
I am hoping it is my vacum chamber but I still have to test it.
Amp, what is the position of your actuator rod out or in?

John

amp

iTrader: (50)

jaj1.. found one of the hose on the ypipe to be loose..
the charge actuator now holds in on idle..
but still does not hold when the car is shut off...
i dont need to pull the vacuum to that chamber to extend the rod out...

ran the boost test at idle with a result of 2 psi...
tested the check valve to the pressure tank..
couldnt muster enough pressure to exhale through the valve...
had to use a compressor blow gun to generate some flow through the valve...
wonderin if this is the issue for me...

jaj1

Amp,
When I checked my checkvalves it did not take much effort to blow through them in the direction of the arrow.
With my problem I'm thinking it is a vacum issue. What I have done so far to think this, is
looking at the vacum chamber after running the car shut it off and pull the hose that goes to the vacum chamber you should be able to hear air rushing in to the vacum chamber. I don't hear any air rushing in. I have also started the engine and at idle pulled the hose off the vacum chamber and I could feel that there is sucking at the end of the hose. Now I have to test to make sure that my vacum chmber is able to hold vacum and is not leaking. I am hoping that this is the problem.

John

amp

iTrader: (50)

can someone confirm this..
i read the same.. although it should eventually retract out considerin....
thats the position you start off with.. meaning.. rod out and no vacuum with the motor off....