I have been struggling to find a audible boost leak at high engine speeds/high load.

I removed both the charge relief valve and air bypass valve to test them.

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

In this diagram of the valve, both valves when tested could not hold any boost pressure in port "C". According to this website, port "C" should be able to take 30 inHg of boost pressure.

To me, this sounds like both valves are bad, yet I hear these rarely fail. Am I correct in this diagnosis?

Thanks for the help,

Kevin

 

not sure but don't forget to also closely inspect the rubber hoses attaching them. one of mine split once.

 

I've never tested mine. Are you suppose to have pressure at port 'B' when testing port 'C'?

 

I'm not sure you did the test proper:

"Test for leakage and operation. With nothing connected to port (A), verify that port (B) can hold 15 psi of pressure and/or that port (C) can hold 30 inHg."

Port B should hold 15 PSI of pressure. Port C should hold 30 inHg of vacuum (at least that's how it reads to me).

 

That's how I read it first as well, but I reread it and there is a period after "inHg" and it talks about vacuum being applied to port "A".

The way the sentence is worded to me means 15 boost pressure at "B" or 30inHg boost pressure at "C".

But the thing is that the turbos will be supplying boost pressure at "C", therefore it should stay shut if port A is at atmospheric. Otherwise boost would just be leaked back into the intake.

Can somebody clarify this?

 

Boost is never measured in inHg, only vacuum. They are specifically talking about the flow of air from Port B to Port C which would mean vacuum for Port C. The fact that they specify inHg shows they are referring to vacuum and not boost though. I would test the valves as they have stated on the site.

I haven't looked yet, but I would imagine there is a test in the FSM as well. If it's not the same, maybe it can verify that test.

 

im sorry but i believe this test is flawed.

when i was troubleshooting a boost issue both my CRV and BOV failed the 15 PSI test, i bought a BRAND NEW CRV for 110 dollars from ray and a used BOV from a forum member. BOTH failed the 15 PSI test. i just used the CRV and returned the BOV.

i now boost perfect and i dont think either of those were my problem. i used a mity vac.

i would go by the FSM test for those 2 valves.

 

Can you either describe the FSM testing procedure or point me to the right page in the manual? I downloaded the electronic manual, but it is a pain to go through all of the pages electronically.

 

Not much there, but here it is:

 

CarbonR1, does it sound like running nails over a chalkboard

 

The boost leak actually kind of does. A really loud screech, duck quail at high load/rpm.

 

I'm going to bring this one back up and please think about it for a moment and let me know your thoughts. I think we all agree it is the "C" side of the valve that is getting boost from the secondary turbo. Why on Earth then would you want to test to see if "C" can hold vacuum? wouldn't you want "C" to hold pressure (as it does while boosting? Mine is not holding pressure, and therefore I assume it is bad. Does someone have one lying around they can test? Thanks.
--Jeff

 

Port C is the one that must hold boost pressure, so test it to 15PSI (or above max boost that you will run) without applying vacuum to port A.

When vacuum is applied to port A, it pulls a diaphram which opens the valve against a spring which otherwise keeps it closed.

Test that you can blow through from port C to B or vice versa when about 10inHg vacuum is applied to port A. If port A won't hold vacuum, the valve is bad. If the diaphram has ruptured, you will have a leak from port C when testing pressure as well; otherwise the case itself is leaking (which should be obvious looking at the case from the outside).

 

Thanks. You are saying exactly what I was trying to say. For some reason, the instructions for testing on the autosportracetech.com site (which is one of the best sequential turbo sites) says to apply pressure to Port B to see if it will hold, "verify that port (B) can hold 15 psi of pressure" then it goes on to say "and/or that port (C) can hold 30 inHg." It seems to me this is exactly opposite of what it should be.

 

just do as i did!

put CRV to mouth.....blow on "B" ....nothing should be heard and no air should flow.

do the same thing to side "C"............should get same results.

now, make your wife or girlfriend(anyone you dont mind being in face to face contact with,lol) suck on port "A".....now blow into port "B" or "C"....air should now flow! lol

as retarded as that is, thats what i did(no tester around at the time) and it passed the test!