Perth-WRX.com  

Go Back   Perth-WRX.com > Technical > Mechanicals
Register Diddy Kart ArticlesAll AlbumsBlogs FAQ Members List Calendar Search Today's Posts Mark Forums Read


Welcome to Perth-WRX, click here to register!

Like Tree9Likes

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 13-06-2013, 08:57 AM
zskarz's Avatar
Potty Training Scoobie Noobie
Member
 
Join Date: Aug 2012
Location: Canning Vale
Posts: 46
Thanks: 1
Thanked 2 Times in 2 Posts
zskarz at standard level
Default 07 STi Backfiring

Hi Guys,

Kinda new to the forum and have recently purchased my very first wrexy it's an 07 WRX Sti. It came with some nice mods; turbo back, walbro fuel pump and BOV, the car had also been tuned to around 260whp which from what i have read is safe. I really like the car and the way it sounds, however hearing the engine backfire doesn't sound good and in my eyes can't be in anyway good for the engine. I was told that it's backfiring due to the fuel pump drinking more than it should and the bang is excess fuel that hasn't been used. Just hoping someone can shed some light on the matter, is it worth having it tuned again or?

Also not too concerned on stopping this if it's not going to destroy the car.

Cheers

Last edited by zskarz; 13-06-2013 at 09:02 AM.
Reply With Quote
  #2  
Old 13-06-2013, 09:02 AM
Addy's Avatar
Sign me up!
Santa's Little Helper
 
Join Date: Feb 2010
Location: Como
Posts: 338
Thanks: 6
Thanked 0 Times in 0 Posts
Addy at standard level
Default

Is that just when you lift off? It could be the BOV. I would change it to a plumb back. having some backfire on lift off is normal with the exhaust. Just running a bit rich which is on the safe side. Fuel pump will not cause you to put more fuel in the engine. Any excess fuel will be returned to the tank.

Sent from my GT-I9100 using Tapatalk 4 Beta
Reply With Quote
  #3  
Old 13-06-2013, 09:08 AM
Emjay's Avatar
WRX Hi Five Club
Member
 
Join Date: Feb 2013
Location: Caversham
Posts: 200
Thanks: 10
Thanked 2 Times in 2 Posts
Emjay at standard level
Default

I'm sorry, i cant answer your question though I'm curious of this too.

My car does it quite frequently, everyone told me that its OK "its a WRX thing" or something. took my car down to the drags and both times I've hit limiter and backfired but this time a big flame came out the exhaust. everyone said that was fine too...

im not sure of the technical side of it but in my car apparently soemthing has been swapped and that it send the same amount of fuel through, and thats why. But i'm not good at this stuff.

So in all my jabble i'm looking for a more mechanical reason
Reply With Quote
  #4  
Old 13-06-2013, 09:23 AM
grape juice's Avatar
WRX Hi Five Club
Member
 
Join Date: Apr 2009
Location: Carabooda
Posts: 219
Thanks: 21
Thanked 4 Times in 4 Posts
grape juice at standard level
Default

I'm not expert so please correct if i'm wrong,

Its probably the atmospheric BOV thats causing the backfiring (It's not an issue)

I believe it caused by an excess of fuel in the system, this occurs when the BOV releases air into the atmosphere it causes a temporary unbalance in the air/fuel ratio being combusted. With it being slightly richer thats when you'll find it popping and backfiring.

I have an 05 Sti with indentical mods, and its occured once or twice when i missed a gear whilst reving it out hard.

Having an 'atmospherioc BOV' will increase your fuel consumption slightly due to these unbalanced ratio's. Alot of people would suggest switching it back to the standard plumb back model (which i would if i could click my fingers and have it changed). The only beneficial/reasons why people put them as far as im aware is

1) They like the sound it makes
2) Slightly improved throttle response (i think due to temporary richness after shift)
3) I've read the standard ones CAN start to leak around 22ish psi?

From my understanding it isnt necessary at all unless chasing big power. and i would remove it next time you were getting you car tuned.

Again this is all information i've read online (unfortunately a lot of online information is opinion and wrong) so if im off target with anything here some one correct me.
__________________
A man in nature;

"All in relation to nothing. Nothing in relation to infinity. A central point to both, And infinitely far from understanding either."
Reply With Quote
  #5  
Old 13-06-2013, 09:27 AM
Brett Allan's Avatar
Subaru Tech Division
Member
 
Join Date: Jan 2011
Location: NOR scum
Posts: 1,395
Thanks: 49
Thanked 41 Times in 39 Posts
Brett Allan knows their stuff
Default

Backfiring is normal for most WRX's with an exhaust and bolt on modifications..

Usually on downshift and feathering the throttle will cause this.

If the car is doing it excessivley and running very rich, it would be worth getting the AFR checked and possibly retuned.

Emjay, does your car have antilag enabled? That would be the cause of the flames...
__________________
2005 WRX STI
Reply With Quote
  #6  
Old 13-06-2013, 09:36 AM
Emjay's Avatar
WRX Hi Five Club
Member
 
Join Date: Feb 2013
Location: Caversham
Posts: 200
Thanks: 10
Thanked 2 Times in 2 Posts
Emjay at standard level
Default

I dont even know what that means! hahahhaa!!! how would I find that out??

Quote:
Originally Posted by Brett Allan View Post
Backfiring is normal for most WRX's with an exhaust and bolt on modifications..

Usually on downshift and feathering the throttle will cause this.

If the car is doing it excessivley and running very rich, it would be worth getting the AFR checked and possibly retuned.

Emjay, does your car have antilag enabled? That would be the cause of the flames...

Last edited by Emjay; 13-06-2013 at 09:37 AM.
Reply With Quote
  #7  
Old 13-06-2013, 09:45 AM
zskarz's Avatar
Potty Training Scoobie Noobie
Member
 
Join Date: Aug 2012
Location: Canning Vale
Posts: 46
Thanks: 1
Thanked 2 Times in 2 Posts
zskarz at standard level
Default

it only backfires when slowing down and it's just literally one loud bang, a few seconds after getting off the gas. The BOV is a turbosmart. Thanks for the info.
Reply With Quote
  #8  
Old 13-06-2013, 09:48 AM
redlib's Avatar
Subaru Tech Division
Member
 
Join Date: Sep 2007
Location: Perth
Posts: 1,263
Thanks: 3
Thanked 5 Times in 5 Posts
redlib at standard level
Default

No her car does not have antilag.
Emjay likes this.
Reply With Quote
  #9  
Old 13-06-2013, 09:58 AM
Strubaru's Avatar
Perth WRX Old Skool Cool Dude
Member
 
Join Date: Aug 2006
Location: the narcotic suite
Posts: 3,511
Thanks: 14
Thanked 39 Times in 38 Posts
Strubaru knows their stuff
Default

no catalytic convertor either by the sound of it (flames)
Reply With Quote
  #10  
Old 13-06-2013, 10:29 AM
Tiigga's Avatar
STI Master
Member
 
Join Date: Jul 2011
Location: High Wycombe, Perth
Posts: 579
Thanks: 42
Thanked 13 Times in 13 Posts
Tiigga at standard level
Default

Quote:
Originally Posted by Emjay View Post
I'm sorry, i cant answer your question though I'm curious of this too.

My car does it quite frequently, everyone told me that its OK "its a WRX thing" or something. took my car down to the drags and both times I've hit limiter and backfired but this time a big flame came out the exhaust. everyone said that was fine too...

im not sure of the technical side of it but in my car apparently soemthing has been swapped and that it send the same amount of fuel through, and thats why. But i'm not good at this stuff.

So in all my jabble i'm looking for a more mechanical reason

Install small bbq near exhaust and wait for car backfire flame... mmmmmm dinner cooked... no more kitchen
zskarz likes this.
__________________
It's your car, It's your story,
So don't let someone else write the book.... MCM
Reply With Quote
Reply

Tags
07, backfiring, sti

Thread Tools
Display Modes

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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
2006 subaru liberty gt tuned by sti Serbaru For Sale (Cars Only) 7 12-01-2012 04:04 PM
6 Speed - JDM vs AUDM Kato Mechanicals 11 01-03-2011 08:03 PM
07 STI Manifold (Complete) tropikal For Sale 3 15-06-2009 06:01 PM
EVO IX vs 07 STi perthzed General Subaru Discussion 29 11-06-2007 08:35 AM
Hi guys! New Subaru business check out our stock! subiworx Introductions 0 22-09-2005 08:04 AM



Welcome to Perth-WRX, click here to register!

All times are GMT +8. The time now is 08:51 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO