Bypass Valve fix/Possible Boost Mod
I, on the other hand ....will be rocking a 98 sunfire AUTO
lol......It's an Ebrake slidding machine. It's kinda fun driving a car you don't care about at all ... no door ding or pothole stress.
Senior Member
Joined: 03-05-09
Posts: 1,028
Likes: 2
From: Des Moines, IA
Hey, it could be worse.... I rocked this HOT purple SunBIRD one Winter. $200 bucks and a lot of motor honey later we got to spring again 
It did snow here last weekend, but thankfully they didn't feel the need to spray brine everywhere. Otherwise I wouldnt even drag it out of the garage one last time.
---
EDIT
So.. .what am I logging here tonight?
Stock
With tank removed
With solenoid AND tank removed
?
It did snow here last weekend, but thankfully they didn't feel the need to spray brine everywhere. Otherwise I wouldnt even drag it out of the garage one last time.
---
EDIT
So.. .what am I logging here tonight?
Stock
With tank removed
With solenoid AND tank removed
?
Last edited by Gimpster; Oct 13, 2009 at 06:02 PM. Reason: Automerged Doublepost
Senior Member
Joined: 03-05-09
Posts: 1,028
Likes: 2
From: Des Moines, IA
OKAY, I tested stock, without tank only and then solenoid totally removed from system just now. You guys are lucky I like you, because it started to sprinkle as I did the second test. I spent like 12 hours washing over, under and waxxing the car 3wks ago
I'll wait until I get them side-by-side in Excel, but at this moment I can tell you there were no gains in boost @ upper rpm ranges. Not sure about boost recovery between shifts until I get the data in there.
Gimme a lil bit.
I'll wait until I get them side-by-side in Excel, but at this moment I can tell you there were no gains in boost @ upper rpm ranges. Not sure about boost recovery between shifts until I get the data in there.
Gimme a lil bit.
Senior Member
Joined: 03-05-09
Posts: 1,028
Likes: 2
From: Des Moines, IA
https://www.cobaltss.net/forums/show...87#post4376287
There are the testing results, I figured it deserved a new not 9 page thread.
HHRSSouth, some people claimed to see more boost... which I knew wouldnt be the case and the data confirms that to me. Unless the PCM was commanding the BPV to crack open up top, there was no way.
There are the testing results, I figured it deserved a new not 9 page thread.
HHRSSouth, some people claimed to see more boost... which I knew wouldnt be the case and the data confirms that to me. Unless the PCM was commanding the BPV to crack open up top, there was no way.
Hey, it could be worse.... I rocked this HOT purple SunBIRD one Winter. $200 bucks and a lot of motor honey later we got to spring again
It did snow here last weekend, but thankfully they didn't feel the need to spray brine everywhere. Otherwise I wouldnt even drag it out of the garage one last time.
---
EDIT
So.. .what am I logging here tonight?
Stock
With tank removed
With solenoid AND tank removed
?
It did snow here last weekend, but thankfully they didn't feel the need to spray brine everywhere. Otherwise I wouldnt even drag it out of the garage one last time.
---
EDIT
So.. .what am I logging here tonight?
Stock
With tank removed
With solenoid AND tank removed
?
Joined the dark side it see lol. I remember when I traded my SC i had buyer's remorse cause i missed the SC whine and instant throttle response. That lasted till i got the S.chips tune. Good luck with the new ride/
Senior Member
iTrader: (1)
Joined: 11-29-06
Posts: 4,105
Likes: 0
From: New Minas, Nova Scotia, Canada
Well I triedthis last night an my car felt a little slower response wise. It took longer to build boost as well. But I am having issues with boost flutter when I'm in vacuum below 0psi, so would this conclude that I have a vacuum leak somewhere?
well I've had it done for awhile now, I don't have any boost flutter below 0 psi... my bpv is more responsive... still waiting to get my data-log back from Vince to see if any performance was lost.
New Member
Joined: 01-24-11
Posts: 42
Likes: 0
From: hanceville al
Thread Starter
Senior Member
Joined: 07-12-08
Posts: 605
Likes: 0
From: Houston, TX
No. You are bypasing the vacume tank. If you actually trace the three vacume lines that are on the front of the motor you will see exactly how its done. I believe there are pictures in the thread aswell. And no you dont see more boost. if you have a vacume leak then your Bypass valve will crack open and you could lose a little boost up top. It will make your valve response go up slightly since your getting rid of extra line and a box that has to be filled first.
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.
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'm always leary when you try to *outsmart* the engineers. This tank stores vacuum *on tap* for quick BPV release when needed to prevent turbo surge. There are a TON of posts here...back and forth but nothing here convinces me. Anyone here with it NOW? Feed back appreciated.
