bypass valve???

black_bird89

Registered User
is that a waste gate or bypass valve on top of the intake?

and if its torn on the inside would this cause bucking during boost....

here is an example of what my car is doing it will go in low boost(3~4psi) but above that it will make a wierd noise and the boost will shoot up and the car will have no power...I just cant figure this out it drives normal in vaccuum or until i get over 3~4psi
 
is that a waste gate or bypass valve on top of the intake?

and if its torn on the inside would this cause bucking during boost....

here is an example of what my car is doing it will go in low boost(3~4psi) but above that it will make a wierd noise and the boost will shoot up and the car will have no power...I just cant figure this out it drives normal in vaccuum or until i get over 3~4psi

my car did this with a bad dis, located on the bracket above the a/c compressor....
 
is that a waste gate or bypass valve on top of the intake?

and if its torn on the inside would this cause bucking during boost....

here is an example of what my car is doing it will go in low boost(3~4psi) but above that it will make a wierd noise and the boost will shoot up and the car will have no power...I just cant figure this out it drives normal in vaccuum or until i get over 3~4psi

It is a bypass valve and Im not sure what you would consider torn. It has a metal disc that turns sideways to allow for bypassing the blower. It is possible it could stick causing your boost to be low or non existing.

Ken
 
>when i push the rod that goes into the gold colored cylinder it sounds like a torn diaphram

There is a vacuum diaphragm that operates to move a rod, arm & plate/bypass valve.

Rev the engine while watching the rod to see if it moves. It should move when the engine is started and run at idle, as vacuum is built and fed to the diaphragm, and stay in that position until the engine is allowed to build boost and vacuum drops - then it will move the rod connected to the plate.

If the diaphragm in the vacuum canister is borked, it won't move the rod/arm at all.
 
i will try to post a video tomorrow.

vacuum is reading 25 to 30ish i don't really remember but it's stock I don't believe there's a vacuum leak
 
>it will go in low boost(3~4psi) but above that it will make a wierd noise and the boost will shoot up and the car will have no power...I just cant figure this out it drives normal in vaccuum or until i get over 3~4psi

Auto transmission or manual? When the boost 'shoots up', does the tach do the same thing?
 
ok my vacuum is at @18 not 25 t0 30ish but my car idles up high on its own so that could be the reason for the low vacuum reading and it is a manual and my tach doesn't work but it sounds like the engine cuts out when the boost jumps up
 
Sounds like it could be an ignition problem (DIS or crank sensor). But it's hard to guess at.

Here is an easy way to see if the bypass valve diaphragm is torn. With the car off, disconnect the vacuum line and manually move the rod to open the valve. Put your thumb over the line on the canister. Does it hold the vacuum and keep the valve open? If not, you have a problem. If it holds, then it is probably good.
 
99% of the time, bucking under boost is cured by replacing the plugs and wires. Boost and tach readings will be all over the place when this is happening, so I wouldn't get too concerned about what they show.

If plug wires are pretty old, they can be damaged just by changing plugs.

David
 
I wondering if there is a slipping clutch involved, where it releases under boost.

Boost goes up....revs go up...car goes nowhere.
 
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