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I did it for that reason and I read all these threads last night about faster spooling, quicker blow off, and even a power increase! Cost me $1.78 for the 5" piece of a vac line and like 10 minutes of my time, no tears here.
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.
I just recently replaced my MAF sensor and both MAP sensors with hopes of solving some CELS iv been throwing for a while now. What you describe seems to be very similar to what my car is going through. I upgraded to 3 bar bosch sensors. However, before replacing anything my car would run max boost between 20-21psi. Yet i did not have those 3 bar sensors that usually come with the gms1( which i assumed why my car ran such high boost) but after swapping out these sensors my boost pressure likes to do its own thing. Sometimes boosting between 13-15psi. Sometimes 15-18. And sometimes 2.5psi. One other odd thing has been the blow off sound when getting out of throttle. It sounds like a diesel (chos* chos* chos*) not at all like the classic turbo blow that our cars make. And it only started doing that after the MAP sensor swap. Im gonna try deleting the vac tank and see if that helps. Anybody have any thoughts on this problem.
You got a tune after upgrading to 3 BAR MAP sensors right?
Negative. I ran out of money and was hoping i could do without for a little while.. should i swap back to stock MAP sensors or can i surivive until i get cash for a tune?
Negative. I ran out of money and was hoping i could do without for a little while.. should i swap back to stock MAP sensors or can i surivive until i get cash for a tune?
Nope you have to have a tune. It's a very minor change to the tune file but it's still required
Nope you have to have a tune. It's a very minor change to the tune file but it's still required
Any source i can just get the GMS1 tune from? And what would i need to get it flashed to my car. I dont have any tuner, nor have i done any tuning to my car previously.
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?
The red circle is coming from the bpv at the turbo, the line closest to the dipstick is connected to the vac tank and would be connected to the manifold
The red circle you dont have to touch, the bottom hose goes to the tank then another line at the tank goes to manifold what you are doing do pretty much is get rid of one line and the tank
01-06-2017, 02:13 AM
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