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Discussion Starter · #1 ·
Is the hooter valve/recirc valve/bypass valve whatever it is suppose to be open at idle? I pull the vac hose of f it and it snaps shut. Could be my stalling problem. I thought it was suppode to be shut but then I'm not sure.
 

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Discussion Starter · #3 ·
The recirc valve on the intake to.release manifold pressure off acceleration. I unhooked it and plugged the holes it was in. applied vaccuum it opened. Took it off it closed
 

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Might be talking about the flap under the hood vent?
My thought exactly.
I was trying to tease out a better description. A doctor told me once that if you keep asking questions, the patient will tell you what's wrong with him.
I asked that question because I don't know how you could see the bypass valve work.

If you took it off you could observe its function, but if it doesn't leak vacuum, and it doesn't 'Hoot', it's OK. There's no need to take it off to test it.
 

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so should you not be able to blow through the valve when there is no vacuum applied but be able to blow through the valve when vacuum is applied?

I have a strange vacuum leak on my car and have no idea where it may be coming from considering almost every component is new... Except the bypass valve and the hose it is mounted to...
 

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If it doesn't sound like a dying duck under acceleration than I wold say its ok. You need to do what Jim said ^^ test it to see if it holds vacuum, if it does than its not broken ;ol;
 

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Discussion Starter · #7 · (Edited)
I did more research, the bypass valve needs to be closed at idle and only open when it releases boost. If you were to plug the hoLes the valve was plugged into and apply vaccuum, and you can blow through it its bad. It has to be closed at idle or its like a big vaccuum leak and will stall the car when declerating with.clutch in.

It doesnt HAVE to sound like a dying duck. It is a symptom, thats when the diaphram speings a leak. But if the valve has a bad spring and is weak, the vaccuum will suck the piston open creating a leak. It should have just enough spring pressure to keep the valve shut at full vacuum.

When you're on boost, the presure supplied to the top of the valve via the vacuum line equalizes the manifold pressure keeping the valve shut. Then when you lift your foot the line releases pressure allowing the manifold pressurr to push its way out of the valve, then when the pressure is gone the spring tenaion allows the valve to close so you dont have a leak. If the diaphragm is bad it wont hold boost, creating a dieing duck. if the spring is bad it wont hold vacuum.
 

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Do more research. Your description of how vacuum, spring and pressure interact is pretty accurate, but I don't think you understand its function.
It doesn't create a vacuum leak when it operates, or if it doesn't seal perfectly. Its only function is to prevent annoying noise. It also has a minor effect of maintaining turbo speed. Early 16v turbos didn't have the valve at all, they created it to eliminate the noise; thus it's called a hooter valve.
If you have no objectionable noise, it's installed properly, and it doesn't leak vacuum through the diaphragm, the bypass valve is not causing whatever problem you're experiencing.
 

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Discussion Starter · #9 ·
Its function is to release manifold pressure so it doesnt wreck your engine. When your throttle closes all that pressure is trapped so it needs a way out or it will surge into the engine and cause damage to engine and turbo. So that valve opens and recycles it to the intake. im pretty sure thats the function of the recirc valve.

I have a minor vacuum leak cause a 200-300 idle wobble and shouldnt be enough to stall the car. It stalls everytime I push the clutch just cruising. Not getting on it. But if I feather the gas before I stop It will stay running. That soundd like a bad recirc valve. I dont have a brake booster as I have abs, and I have new o2, ntc, properly adjusted throttle and tps, swapped AMM, and tps. Im stumped as to what else it could be. I sprayed carb cleaner all over the intake manifold, all vacuum Ports, and I juat have no idea what else it could be. I even checked all the grounds to know avail. It drives 100% no lack of power and no funny issues driving even at low speed. Just idle and coming to a stop.

I pinched and plugged everything I could think off. Check valve is good as well. So im stumped. Recirc valve is my last ditch at this point.
 

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Well, as Sherlock Holmes once said, once you've eliminated all the possibilities what remains is the impossible. Or something like that.

Does this happen only when driving? Is it conceivable that there's a leak inside the car that gets worse when you're pressing the clutch pedal?
 

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Discussion Starter · #13 ·
Inside the cabin...... What supplies vacuum to the vent controls??? Where is that vacuum line? Its not the same one that goes to the apc dial because I had that unplugged and blocked to check the presure transducer etc. and I - know my vent controls still worked.


If I'm not moving I can rev it all day long no issues and right back to the wobbling 900 rpm idle. I dont think the clutch is connected trio anything that would cause vacuum issues. Its a 90 spg with abs so its an electrically boosted reservoir. So the clutch would have.nothing to do with vaccuum. I'll try slipping it our of heart without using the clutch on the way home from work today just to eliminate that possibility. Therehas to be some thing else stupid im missing.
 

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Its function is to release manifold pressure so it doesnt wreck your engine. When your throttle closes all that pressure is trapped so it needs a way out or it will surge into the engine and cause damage to engine and turbo.
That's just not so, but it also doesn't address your problem.
You cleaned the throttle housing and set the throttle stop screw correctly before adjusting the throttle position switch?
 

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Well, as Sherlock Holmes once said, once you've eliminated all the possibilities what remains is the impossible.
"When you've eliminated all other possibilities, whatever remains, however improbable must be the truth."

Cool saying but useless for diagnosing a 20 year-old machine with 20,000 parts.
 

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Discussion Starter · #16 ·
It releases the pressure so it doeant cause compressor surge wgen the throttle plate closes rapidly. its before the throttle not after duh. I am dumb because I'm trying to think of any reason my stuff.doesn't work. if I have no leaks in the motor next is the vent selextion. wheredoes the vacuum servos for the vents get vacuum from the engine?
 

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It releases the turbo pressure before the throttle, but the controlling hose for it is after the throttle. If the bypass is faulty and leaking the leak, if it exists, is after the throttle, maybe contributing to your idle problems. I think this is not the whole story. A properly functioning AIC can accommodate small leakages elsewhere.
 

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Discussion Starter · #18 ·
Aic is brand new. I probably have a large vacuum leak but it can keep up with it cuz its brand new. I Ned to trace the ventilation system. How does it get vacuum becauae I cant find it.
 

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Discussion Starter · #19 ·
Well its nothing vacuum line related. Im pretty sure now its either the gasket between the throttle body and manifold, or the manifold gasket. It runs great all the way till the car is almost warm, and then it acts up. So the different expansiin rates betweenbthe aluminum and steel must push something apart enough to cause a leak. I checked all vacuum linss warm and cold unplugged the aic while running and it just made it really bad, so the aic is keeping the car as steady as possible. Sooooo off with the TB and manifold after I get back.from Vegas.
 

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Well its nothing vacuum line related. Im pretty sure now its either the gasket between the throttle body and manifold, or the manifold gasket. It runs great all the way till the car is almost warm, and then it acts up. So the different expansiin rates betweenbthe aluminum and steel must push something apart enough to cause a leak. I checked all vacuum linss warm and cold unplugged the aic while running and it just made it really bad, so the aic is keeping the car as steady as possible. Sooooo off with the TB and manifold after I get back.from Vegas.
Ya know...now that I'm tapping into the memory chips in my head...there was a thread on here a while back where someone was having a similar issue. Turned out he was missing a screw underneath the throttle body somewhere. It's underneath like you can't see it unless you have a mirror in your hand.
 
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