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Funky boost dying giraffe sound

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Old 05-15-02, 11:06 AM
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Question Funky boost dying giraffe sound

Problem...

car will often not boost 2nd turbo. and makes a cooing sound (weird)

It will boost 2nd turbo under following conditions:
1. if past 4500 rpm and you boost a little, then let go of gas and quickly floor it again then all is fine
2. if past 4500 rpm and you are not gassing it, but then just stab the gas.

Other than that all you hear is whinning sound from 1st turbo (12psi) then past 4500 it drops down to like 7psi. then if you let off gas it makes a high pitched "cooing" sound that that drops down to nothing. sort of like "HOOOooooo...."

vacuum tanks and pressure tanks are ok. Any suggestions besides TEARING DOWN THE WHOLE SEQUENTIAL SYSTEM AND DOING IT AGAIN!!!!
Old 05-15-02, 11:18 AM
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I have different boost patterns from you but I hear the same noise. At first I thought it was the factory BOV, then I vented those to the atmosphere and can still hear this noise. It kind of sounds like a video game sound effect or something, WOOOOooooooo. I know wexactly what you mean. Dot know what the hell it is. It only happens when my car struggles to make boost too. Only thing I cn think of off hand is something with a bad vacuum, or air pump. I dont know though. WOrking on the car today.....
Old 05-15-02, 11:32 AM
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I thought that noise was the air pump? Mine does it too, but no boost problems... Dying Giraffe.. I like that..
Old 05-15-02, 11:34 AM
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dim - check the vaccum hoses under your Upper Intake Manifold. You don't have to remove it to see in there, just unbolt the vaccum/pressure box (which is it, vaccum or pressure, I forget) (black box between your cross over pipe & UIM) and shine a flashlight in under your UIM. I had the same thing you describe and this is what caused it.



Ya, I had never heard dying giraffe (too hard to spell), but I have heard dying goose sounds from the air pump when I had one!

K
Old 05-15-02, 11:39 AM
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it's not airpump cuz i don't got one but i'll check...

The top one is pressure tank the one by the PS pump is the vacuum tank.
Old 05-17-02, 02:42 PM
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ok i don't find any loose hoses and no visible cracks...

Here is a more descriptive symptom
When i am doing good boost, it's intermittent from 4,500 up to like 5,500. After that it's full boost IF i started from below 4000.

However
as soon as i shift gears and slam it, no boost past 5psi and i hear a wheezing sound while attempting to boost, however if I let go of gas, i hear the dying goose/giraffe sound.

IF
I press in clutch, let the rpms drop and punch it again it goes good.

Could it be the symptom of a dying turbo control dashpot?
Old 05-17-02, 02:57 PM
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Uncontrollable drifter

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Yeah don't know what the hell a giraffe sounds like in the first place let alone dying, but remember that it's not only the hoses that fail but also the solenoids go pretty easily and there are some people who have seen them fail in different temps. only-really screwy, if you can't figure it out just go non and deal with the lag.
Old 05-17-02, 03:15 PM
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mine once had the c-clip come off of the precontrol actuator and it sounded like the hydraulic augmenters on an f15.

beeerrroooooo (muffled and low pitch)

i could boost throungh a gear but it wouldnt reset for the next gear...
Old 05-17-02, 09:47 PM
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looking at the parts diagrams, does the turbo pre-control rod C-clip pop completely off and bounce off onto the street?
Old 05-17-02, 10:26 PM
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all the clips are ok, but the actuator might be going kaputz since i see a little oil coming out of it. Maybe cuz my turbos are dying too thus leaking oil into the vacuum lines thus going into the actuators thus gunking them up. I'm going to disconnect the pre-control lines and plug them up... Any down side to this?
Old 05-22-02, 06:49 AM
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I have been having a similar problem and I have new turbos. Mine will some times get stuck at 2-3 psi on 1st turbo when I try to get on it quickly (like when trying to race) as long as I hold down the accelerator it just stays at 2-3 psi then as soon as I let off it lets out this high piched pbeeoouu sound like a video game sound effect I did the whole vac job and still have this problem.
Old 05-22-02, 09:15 AM
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i checked the actuators, clamp, all...

I still get the same problem... I think maybe my solenoid is toast... or there is a leak somewhere up there... i'm going to hook up my boost meter to the vac tank and see if the vac is holding.

Does anyone know what the vac tank is supposed to be? Does it ever just loose all the vac? How about the pressure tank?
Old 05-22-02, 09:47 AM
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Dimcorner,
You may have a split check valve going to the tca like
Ryan said it sounds like for some reason its not opening.
Unbolt the vacuum tank and look around for any cracked check valves. They will literally split in two and sometimes they look fine but the seal is bad and you can pull them apart so tug on them a little to be sure they are solid. Did you sell your car and get another or just decide to keep it?
Old 05-22-02, 12:28 PM
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if someone shows up to my door with 15k the car is theirs...

All check valves are good. I have a feeling it's the Turbo control solonoid or a split line somewhere. I tied the boost controller to the chamber a of the charge control actuator and this is what I see...
Vaccuum all the way to 4.5k.
After 4.5k it becomes atmospheric
but if i shift gears it stays open
if it's below 4k it stays open
it will only close if i drop the rpm's below 3k

Also when the 2nd boost comes on the first time it makes a intermittent wooshing sound like if a gate is being slapped around... I disconnected the ECU control of the WG and the precontrol and it still happens. My guess is that it is either the vacuum side or the pressure side of the turbo control actuator on bottom. I'm going to hook up my boost gauge on the vacuum tank and see if it's holding vacuum.

Does anyone out there know if the vacuum tank is supposed to loose any of its vacuum during a full turbo run? how about the pressure tank.
Old 05-22-02, 12:40 PM
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thats not paint....

 
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I am not sure how much the tanks are suppost to hold but listen to this...
Vacuum Chamber

This is a black plastic tank that is buried between the alternator and power steering pump. Kind of difficult to see, removing the Pressure Chamber helps to see it, has one hose connection, and should have a hose attached. This hose comes from the rats nest of metal tubes, and there is a one-way check valve between the rats nest of tubes and the Intake. This one-way check valve can start to leak after a while, causing loss of vacuum to various controls when under boost for a while. A way to troubleshoot this one-way valve leaking is to note a gradual loss of boost and then drop the throttle long enough for your boost gauge to indicate at least 20 inHg of vacuum then slam the throttle back down again. If boost is back up to what it should be then replace this one-way check valve. Basically what this does is "recharge" the vacuum chamber when you let off the gas, allowing actuators to operate properly while the vacuum is still present.
The vacuum one-way check valve goes from the Intake manifold to the Vacuum Chamber via the rats nest of tubes, (Mazda Part# N390-13-995A). This has a layer of three paper like filters on each end for separating any oil from the air.
Try replacing that check valve, if that doesn't work then maybe a bad solenoid somewhere. Also check to see if the check valves are not backwards. That check valve should be letting boost flow from the Ypipe to the pressure tank but not back. Check all the other valves as well, they should flow TOWARDS the UIM.

-Chris

Last edited by 7-sins; 05-22-02 at 12:42 PM.
Old 05-22-02, 01:39 PM
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I'm still betting its a check valve to the tca. Be sure to post the final outcome. Good luck getting the dying giraffe out of your engine
Old 05-22-02, 03:35 PM
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i did the poor man's sequential and the turbos are fine and they kick in good...

Here is my question... If I wanted to do the turbo simplification...

There is one line that goes from the pressure tank to the LIM. But i don't know if that is correct or not cuz the other side doesn't have a line that leads to a pressure source. Anyone out there do that mod?
Old 07-09-02, 10:42 PM
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I have the same Dimcorner's problem with a strange sound depending on my RPM when I shift into second gear. Sometime i've got no boost and a strange sound.... but if I shift into second gear at low RPM in first , all is ok . With that problem i'm not able to race at a stop....... I can't push hard into first gear!!! :0(

Kevin, QC, Canada 94 FD
Old 07-09-02, 11:29 PM
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Did you make sure that there really truely are not any dying giraffes under your hood? The pressure from the second turbo may be hurting the poor thing....
Old 07-09-02, 11:36 PM
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Originally posted by NoFear99
I have the same Dimcorner's problem with a strange sound depending on my RPM when I shift into second gear. Sometime i've got no boost and a strange sound.... but if I shift into second gear at low RPM in first , all is ok . With that problem i'm not able to race at a stop....... I can't push hard into first gear!!! :0(

Kevin, QC, Canada 94 FD
Check the hose to the BOV, mine needed to be replaced. Once the hose warmed up from the engine heat, it made an aweful sound under boost.
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