Bypass Valve fix/Possible Boost Mod
#212
In consistent boost issues.
This should be a sticky if we can make it, After about an hour of trouble shooting and test runs i have found out why my car would only boost to about 10 psi, sometimes 14psi, and other times only 5psi. Its another one of GM's contraptions that hasnt worked for me. I have heard others talking about this so i did some research and turned some bolts and this is what i found. THIS MAY ACTUALLY BE A BOOST MOD. I am boosting 18psi
now that i have done this. Im not sure what the factory boost setting is so correct me if im wrong.
HOW IT WORKS:
The LNF has a recirculating bypass valve/Blow off valve located on the passanger side of the turbo. It is held on by three 10mm bolts and a vacum line in the middle of the plate. When throttle is released vacume travels throught the lines pulling back on the valve and releasing it backwards through your air intake/air filter after the MAF sensor.
THE PROBLEM:
On a scanner or code reader, you will see a turbo/supercharger bypass mechanicle code. You may get random codes about unexplained air/fuel misreading. Your car will boost to the propper level sometimes but not always, seeing a varitation of boost levels between 0-10psi.
WHAT CAUSES IT:
There are three actual problems that can occure, a leaking vacume line, actual bypass valve stuck in the turbo, or the GM engineered vacume tank may be leaking or have a bad check valve inside. The tank is there to help build and store vacume to help with "faster spool times" and make it more "responsive". IMO it does nothing but get in the way and cause problems. I felt like it spooled faster and was more responsive after i removed it.
THE FIX:
If it is your vacume tank you can easily bypass it in about 3 mins. There are three vacume lines coming up the front of the motor by the dipstick. One from your MAP sensor and other two from your vacume tank. First remove the Vacume line that comes up and goes into the top of the intake manifold then remove the vacume line closest to the dipstick on the bypass solinoid "where they all meet". cut about 5"-6" of vacume line off one of the lines you removed and plug it into the manifold and where you just disconnected it from the solenoid. Go for a drive and see if it solves it. If so then you can reach the vacume tank from the underside of the car to remove it "one bolt".
After doing this my car felt 10x more responsive, and boosts to 18psi consistantly. IDK what the actual factory boost setting is but it feels alot faster than what it felt at 15psi. And of course you should see a little more power with a little more boost but it made a pretty good difference for me.
now that i have done this. Im not sure what the factory boost setting is so correct me if im wrong.
HOW IT WORKS:
The LNF has a recirculating bypass valve/Blow off valve located on the passanger side of the turbo. It is held on by three 10mm bolts and a vacum line in the middle of the plate. When throttle is released vacume travels throught the lines pulling back on the valve and releasing it backwards through your air intake/air filter after the MAF sensor.
THE PROBLEM:
On a scanner or code reader, you will see a turbo/supercharger bypass mechanicle code. You may get random codes about unexplained air/fuel misreading. Your car will boost to the propper level sometimes but not always, seeing a varitation of boost levels between 0-10psi.
WHAT CAUSES IT:
There are three actual problems that can occure, a leaking vacume line, actual bypass valve stuck in the turbo, or the GM engineered vacume tank may be leaking or have a bad check valve inside. The tank is there to help build and store vacume to help with "faster spool times" and make it more "responsive". IMO it does nothing but get in the way and cause problems. I felt like it spooled faster and was more responsive after i removed it.
THE FIX:
If it is your vacume tank you can easily bypass it in about 3 mins. There are three vacume lines coming up the front of the motor by the dipstick. One from your MAP sensor and other two from your vacume tank. First remove the Vacume line that comes up and goes into the top of the intake manifold then remove the vacume line closest to the dipstick on the bypass solinoid "where they all meet". cut about 5"-6" of vacume line off one of the lines you removed and plug it into the manifold and where you just disconnected it from the solenoid. Go for a drive and see if it solves it. If so then you can reach the vacume tank from the underside of the car to remove it "one bolt".
After doing this my car felt 10x more responsive, and boosts to 18psi consistantly. IDK what the actual factory boost setting is but it feels alot faster than what it felt at 15psi. And of course you should see a little more power with a little more boost but it made a pretty good difference for me.
#214
#217
#220
I want to bring this thread back up...I want to do this mod to see if it eliminates the issue I am having before I replace the bpv...With the picture I have been looking at it, am I taking a hose and connecting it from the red circle to the yellow? The original post says that I need to take the hose closest to the dipstick (below the red circle) and put the hose from that spot to the yellow one?
#225
Senior Member