Loud pssssshhhhh sound under hard boost?
07-11-2005, 02:36 AM
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Loud pssssshhhhh sound under hard boost?
This one is driving me crazy!!! The set up: chips, shimmed wastegate, Lindsey boost enhancer, stock AFM w/cone filter, stock wastegate. Very consistant 14 lb of boost.
This set up has worked for over a year just fine. The other day I started loosing boost (down fro 14lb to about 9 to 11lb) Consistant 17 to 20 lbs of vacuum at idle and in between shifts.
The noise is always under HARD boost and is consistant until I let off the gas.
In 1st sound is not to loud , 10lbs tops stock BOV dumps and makes correct psshh sound
In 2nd the sound gets real loud at around 8lbs
In 3rd on highway if I really get on it it is just one REAL LOUD consistant "air hose on a compressor leaking sound" , again 10lbs. 4th gear is the same.
Things I have already checked:
removed and inspected stock BOV also used pulled a vac and it is OK.
I have checked out EVERY hose and clamp.
I have pulled the wastegate hose loose from the cyc valve and charged it with about 18lbs no leaks valve works properly.
I have visually inspected all exhaust pipes, no cracks.
Only other thing I can think of would be to somehow pressureize the system right after the turbo but the correct vacuum reading says the intake side is probably ok.
Not being able to produce the noise while stopped makes this case hard to crack.
Has anyone had this happen and what did you do?
Thank you very much!!
This set up has worked for over a year just fine. The other day I started loosing boost (down fro 14lb to about 9 to 11lb) Consistant 17 to 20 lbs of vacuum at idle and in between shifts.
The noise is always under HARD boost and is consistant until I let off the gas.
In 1st sound is not to loud , 10lbs tops stock BOV dumps and makes correct psshh sound
In 2nd the sound gets real loud at around 8lbs
In 3rd on highway if I really get on it it is just one REAL LOUD consistant "air hose on a compressor leaking sound" , again 10lbs. 4th gear is the same.
Things I have already checked:
removed and inspected stock BOV also used pulled a vac and it is OK.
I have checked out EVERY hose and clamp.
I have pulled the wastegate hose loose from the cyc valve and charged it with about 18lbs no leaks valve works properly.
I have visually inspected all exhaust pipes, no cracks.
Only other thing I can think of would be to somehow pressureize the system right after the turbo but the correct vacuum reading says the intake side is probably ok.
Not being able to produce the noise while stopped makes this case hard to crack.
Has anyone had this happen and what did you do?
Thank you very much!!
07-11-2005, 02:42 AM
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One thing that may explain it, a slight slit one of the IC hoses that only appears on boost, as the pressure opens it up, that explains why you get increased noise on more boost. And the slit would not be visible on inspection, but appears under pressure...
07-11-2005, 02:46 AM
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I was thinking of trying to find some kind of stopper like the ones used to check pressure on a radiator to try to pressurize the complete system, what do you think?
07-11-2005, 02:53 AM
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You are leaking Boost from somewhere! The problem is, you can't build boost unless the engine is under load, so it will be tough to diagnose this. Did you check the WG control bung on the IC pipe? How about that line to you boost controller. Maybe the boost controller itself is leaking boost? I have had the same thing happen to me, where the bypass valve popped off, and that bung in the IC pipe was wide open. You have a small boost leak somewhere for sure. Start looking harder.
07-11-2005, 02:55 AM
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Yes buy new ones to replace the almost 20 yr old ones, get them in red 
then try it, then hit the dyno either way, 1 to test power, 2 to find the source of the sound
then try it, then hit the dyno either way, 1 to test power, 2 to find the source of the sound
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07-11-2005, 03:00 AM
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Originally Posted by TurboX
my turbo makes a loud woosh/psshh sound under boost :x
07-11-2005, 03:01 AM
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I still might hit the Radiator shop tomorrow and look for a working stoper. I have seen one where it fits in where the rad cap goes and has a schrader valve where you can charge what ever it is plugged into.
07-11-2005, 03:02 AM
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The issue is you dont know where the leak may be, it could be under or near the clamp! Also, it may not actually be leaking! But new hoses is not a bad idea anyways...
07-11-2005, 03:11 AM
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Other than the cold side of the turbo charging leaking, charging the system with compressed air at the output of the turbo should expose the leak, essentualy creating turbo boost with out the motor even running. yes/ no?
07-11-2005, 03:24 AM
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By shoving the stopper into the IC pipe from the turbo. You should be able to pressurize the complete system from the turbo to the head and all branches in between.