still don't understand bov - Subaru WRX Forum
 
LinkBack Thread Tools Display Modes
#1 Old 03-18-2010, 10:52 AM
WRXtuners Member
 
Join Date: Mar 2010
Location: Texas
Posts: 10
Images: 2
guitarguy20 is an unknown
still don't understand bov

Maybe I'm thinking to hard on this or something. I've read through all the bov threads, the faq, and searched. But I don't understand how a BOV will cause your car to run rich. Whats the theory behind it? I need to pro-tune on my car, and about to get it done. But what I don't get is how the BOV cause's your car to run rich? I understand that it's design is to release pressure after a set point, and make a cool sound. Please explain this theory or direct me to where I can read up on it.
guitarguy20 is offline  
Sponsored Links
Advertisement
 
#2 Old 03-18-2010, 11:17 AM
WRXtuners Member
 
Join Date: Dec 2008
Location: Alberta, Canada
Posts: 60
Images: 1
v8killr is an unknown
When air comes into the intake it is read by the MAF sensor and sent to the throttle body etc. When you run a BOV you run rich because it releases air after your MAF sensor has already read the amount of air coming in causing the ECU to continue to dump the required amount of fuel before the bov released. This results in you getting more fuel then needed causing you to run rich. This can cause on occasional popping noise and your exhaust tip to appear black.

Correct me if im wrong, but im pretty sure that is why.
v8killr is offline  
#3 Old 03-18-2010, 12:09 PM
WRXtuners Member
 
man show's Avatar
 
Join Date: Apr 2007
Location: Maryland
Posts: 3,139
Images: 2
man show is a WRX expert worth listening to man show is a WRX expert worth listening to man show is a WRX expert worth listening to
man show is offline  
#4 Old 03-18-2010, 12:25 PM
Moderator
 
mosc's Avatar
 
Join Date: Mar 2005
Location: Pennsylvania
Posts: 6,482
Images: 7
mosc is a helpful contributing member
Garage
So... bleh. This is so much easier to explain when you're looking under the hood. Here:


See, the air comes in and is measured by the MAF early in the intake stream. This is effectively what the ECU thinks is getting into the engine. Now, as the turbo gets spooled up and starts adding pressure to your intake, it pressurizes all the air between the turbo and the motor intake (mostly the intercooler). From the computer's perspective, this is all air that's already passed through the MAF and is now being crammed into the motor. Now, when you shift or let off the gas, the car needs to release that excess air in the intercooler and surrounding piping that the turbo crammed in. Remember the ECU thinks this air has already been used by the motor. The BPV then releases the excess air back into the intake stream so that it is still in the system. When you release it to atmosphere, you are taking air that passed through the MAF, air that the ECU thought it was getting, and bypassing your engine. As such, the air to fuel balance gets messed. The ECU thinks it's got more air than it really does (since you released it) and adds in more fuel than it should thus you run rich.

04 STi 16G powered lagless fun
04 WRX: SOLD
mosc is offline  
#5 Old 03-18-2010, 02:27 PM
WRXtuners Member
 
Join Date: Apr 2008
Location: New York
Posts: 454
Images: 1
VisiX is a helpful contributing member
Very simply put, the computer that controls your engine thinks that the air that makes your BOV whoosh sound is still in the system. All adjustments it makes that use the total volume of air as a variable are then flawed. Your BOV is basically acting as an on-shift air leak.

Ryan
2009 STi - Cobb Stage 2
VisiX is offline  
#6 Old 03-18-2010, 06:13 PM
WRXtuners Member
 
Join Date: Mar 2010
Location: Texas
Posts: 10
Images: 2
guitarguy20 is an unknown
Quote:
Originally Posted by VisiX View Post
Very simply put, the computer that controls your engine thinks that the air that makes your BOV whoosh sound is still in the system. All adjustments it makes that use the total volume of air as a variable are then flawed. Your BOV is basically acting as an on-shift air leak.
thank you that's all i needed
guitarguy20 is offline  
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On