Welcome to the North American Subaru Impreza Owners Club Monday December 10, 2018
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > FA Series Factory 2.0L Turbo Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 07-14-2018, 09:17 PM   #1
Subie_Jake
Scooby Newbie
 
Member#: 479006
Join Date: Dec 2017
Default 2015 WRX Stage 2 Exaust Pop

Hope everyone is having a fine Saturday I have a question. While decelerating and revmatching under higher loads the exaust will pop. My best guess is I'm injecting fuel that is not fully ignited but getting compressed and then igniting... I'm still learning. Searched around on google/YouTube but the searches just refer to this as a issue not something that can be recreated like my case.

Is this something that is bad? Sould I stop doing it? Just looking for some guidance really.
* Registered users of the site do not see these ads.
Subie_Jake is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 07-14-2018, 09:23 PM   #2
Subie_Jake
Scooby Newbie
 
Member#: 479006
Join Date: Dec 2017
Default

Quote:
Originally Posted by Subie_Jake View Post
Hope everyone is having a fine Saturday I have a question. While decelerating and revmatching under higher loads the exaust will pop. My best guess is I'm injecting fuel that is not fully ignited but getting compressed and then igniting... I'm still learning. Searched around on google/YouTube but the searches just refer to this as a issue not something that can be recreated like my case.

Is this something that is bad? Sould I stop doing it? Just looking for some guidance really.
Exhaust*
Subie_Jake is offline   Reply With Quote
Old 07-14-2018, 09:40 PM   #3
Straight6
Scooby Specialist
 
Member#: 419593
Join Date: Apr 2015
Default

Depends on a tune. Some do it more than others. Nothing to worry about really. Ever heard of a crackle tune, lol ? People have this implemented on purpose, although I have no slightest idea as to why.
Straight6 is offline   Reply With Quote
Old 07-14-2018, 10:01 PM   #4
Subie_Jake
Scooby Newbie
 
Member#: 479006
Join Date: Dec 2017
Default

Hmmmm alright I appreciate the input.
Subie_Jake is offline   Reply With Quote
Old 07-15-2018, 10:22 AM   #5
Perscitus
Scooby Specialist
 
Member#: 378214
Join Date: Jan 2014
Chapter/Region: Tri-State
Location: Blue Hole
Default

This pops-n-bangs, crackles, etc. fad is just as retarded as it is indeed damaging on anything but a racecar (actually even there it can be damaging).

All its doing is allowing a portion of uncombusted air/fuel mixture (or just the fuel if you will) to make it past the cylinder, out the exhaust valve and into the exhaust piping. Given the temperatures in the exhaust track, the fuel spontaneously self-ignites in little explosions along the exhaust pulses. This is whay causes the sound and in extreme cases (or t00ns) also flames out the tips.

All it takes to implement this is heavy negative timing at very low loads and below idle RPM. This way off throttle, in between shifts, etc, timing will be retarded enough to allow the fuel to flow past the cylinder and do its thing in the exhaust track.

Zero benefits to doing this. On a catted setup its simply asking for a failure as the cat/s clog, melt if the explosions happen close enough to them. On a catless setup, any inline mufflers and poor welds wont hold up to it for too long... the turbo itself wont be too thrilled either.

In extreme cases, turbine components, exhaust ports and exhaust valves can be damaged.

But hey, more power to the BMW, Chevy, Chrysler, Ford, Mercedes crowds that seem particularly fond of these retarded (literally and figuratively speaking) tunes.
Perscitus is offline   Reply With Quote
Old 07-15-2018, 11:00 AM   #6
Straight6
Scooby Specialist
 
Member#: 419593
Join Date: Apr 2015
Default

Quote:
Originally Posted by Perscitus View Post
This pops-n-bangs, crackles, etc. fad is just as retarded as it is indeed damaging on anything but a racecar (actually even there it can be damaging).

All its doing is allowing a portion of uncombusted air/fuel mixture (or just the fuel if you will) to make it past the cylinder, out the exhaust valve and into the exhaust piping. Given the temperatures in the exhaust track, the fuel spontaneously self-ignites in little explosions along the exhaust pulses. This is whay causes the sound and in extreme cases (or t00ns) also flames out the tips.

All it takes to implement this is heavy negative timing at very low loads and below idle RPM. This way off throttle, in between shifts, etc, timing will be retarded enough to allow the fuel to flow past the cylinder and do its thing in the exhaust track.

Zero benefits to doing this. On a catted setup its simply asking for a failure as the cat/s clog, melt if the explosions happen close enough to them. On a catless setup, any inline mufflers and poor welds wont hold up to it for too long... the turbo itself wont be too thrilled either.

In extreme cases, turbine components, exhaust ports and exhaust valves can be damaged.

But hey, more power to the BMW, Chevy, Chrysler, Ford, Mercedes crowds that seem particularly fond of these retarded (literally and figuratively speaking) tunes.


Because racecar. How about this gem:

https://forums.nasioc.com/forums/sho....php?t=2829216
Straight6 is offline   Reply With Quote
Old 07-15-2018, 12:15 PM   #7
Perscitus
Scooby Specialist
 
Member#: 378214
Join Date: Jan 2014
Chapter/Region: Tri-State
Location: Blue Hole
Default

Yup, saw that thread take off last year and like most things on here, decided to ignore it.

eBay flamer kits are all the rage with kids like its 1997 all over again.

Darwin awards to any who place additional spark plugs, injectors, etc in their exhaust track south of the actual engine.

http://www.akamoto.co.uk/flaming-exhaust.asp

https://m.ebay.co.uk/itm/NKE-Exhaust-Flamer-Kit-Flame-Kit-/263611524651?_mwBanner=1&_rdt=1
Perscitus is offline   Reply With Quote
Old 07-15-2018, 04:33 PM   #8
GlarryHoodDIT
Scooby Specialist
 
Member#: 460907
Join Date: Jan 2017
Chapter/Region: RMIC
Location: Colorado
Vehicle:
2016 WRX

Default

How does one decelerate and rev match at high loads? If you're decelerating you're definitely not putting load on the engine, and rev matching, if you know what you're doing, again shouldn't be placing additional load on the engine..........

Guys, I don't think he's referring to the burple tunes with constant popping/backfiring/whatever, he's talking (I think) about the random one off pops you'll hear occasionally from injectors turning on/off and a really open exhaust. It gets exasperated by a really free flowing catback and double being catless.
GlarryHoodDIT is offline   Reply With Quote
Old 07-15-2018, 07:19 PM   #9
Perscitus
Scooby Specialist
 
Member#: 378214
Join Date: Jan 2014
Chapter/Region: Tri-State
Location: Blue Hole
Default

Good point. If thats the case, then there is little that can be done short of a. moving the primary cat (if still present) further upstream, as far up as the AF sensor location will allow b. replacing said cat with a higher cell count better substrate one (say at least 400 cell, metal core, 6" long or more) or adding such a cat if catless c. stepping down to smaller ID piping
d. further AVCS tweaks to minimize it.

If all else fails, and it becomes unbearable - back to stock, sell or trade-in.
Perscitus is offline   Reply With Quote
Old 07-16-2018, 11:56 PM   #10
Schoat333
Scooby Newbie
 
Member#: 452248
Join Date: Aug 2016
Chapter/Region: MWSOC
Location: Cleveland Ohio
Vehicle:
2017 Base WRX
WRB

Default

It's normal. I have a catted Cobb jpipe and the Cobb stage 2 OTS tune. I get it when rev matching sometimes. If you don't want it to happen, wait until the rpms will be a little lower to rev match. The more throttle you have to give, the more chance you will get the crackle.
Schoat333 is offline   Reply With Quote
Old 07-18-2018, 10:35 AM   #11
Subie_Jake
Scooby Newbie
 
Member#: 479006
Join Date: Dec 2017
Default

Quote:
Originally Posted by GlarryHoodDIT View Post
How does one decelerate and rev match at high loads? If you're decelerating you're definitely not putting load on the engine, and rev matching, if you know what you're doing, again shouldn't be placing additional load on the engine..........

Guys, I don't think he's referring to the burple tunes with constant popping/backfiring/whatever, he's talking (I think) about the random one off pops you'll hear occasionally from injectors turning on/off and a really open exhaust. It gets exasperated by a really free flowing catback and double being catless.
A video would probably explain better but if I were to give it a little juice in 3rd and let off to slow down and its sitting at 4 or 5 k rpm then down shift to 2nd putting the engine at around 5 with a blip in the throttle the exhaust will pop. This is even easier to do downhill. When I say load I meant higher rpms hope that explains it better.
Subie_Jake is offline   Reply With Quote
Old 07-19-2018, 01:07 PM   #12
vlad11591
Scooby Newbie
 
Member#: 295970
Join Date: Sep 2011
Chapter/Region: Tri-State
Location: Hamilton, NJ
Vehicle:
2018 WRX
ISM

Default

This happens all the time when I rev match downshift, it doesn't do it if I don't rev match. Not so much on stock tune, but with MAP tune it happens quite frequently.

Nothing to worry about man.
vlad11591 is online now   Reply With Quote
Old 07-20-2018, 11:43 PM   #13
RakumiAzuri
Scooby Newbie
 
Member#: 472102
Join Date: Aug 2017
Location: NOVA
Vehicle:
2018 WRX
Gunmetal

Default

I get turbo farts when I'm at high RPMs and I disengage the clutch. From what I can see it's pretty normal with 3in pipes.
RakumiAzuri is offline   Reply With Quote
Old 07-21-2018, 02:54 PM   #14
Dazzo
Scooby Newbie
 
Member#: 484560
Join Date: Apr 2018
Default

Quote:
Originally Posted by RakumiAzuri View Post
I get turbo farts when I'm at high RPMs and I disengage the clutch. From what I can see it's pretty normal with 3in pipes.
Haha, yep! I have a pro tune from Snail and it only does it when shifting from high RPM like over 6500 or so.
Dazzo is offline   Reply With Quote
Old 07-23-2018, 08:19 PM   #15
nine5raptor
Scooby Newbie
 
Member#: 473534
Join Date: Aug 2017
Location: Kansas City, MO
Vehicle:
15 WRX Prem. w/ HK
CWP

Default

Stock tune. Muffler deletes. Run up to ~6500 under wot and shift. 3-6 pops and bangs about Everytime.
Same with map 91 tune. Both on 93 octane.

Last edited by nine5raptor; 07-23-2018 at 08:46 PM.
nine5raptor is offline   Reply With Quote
Old 07-23-2018, 09:38 PM   #16
cyralax
Scooby Newbie
 
Member#: 425154
Join Date: Jul 2015
Chapter/Region: W. Canada
Vehicle:
2016 WRX Sport
Lapis Blue Pearl

Default

I get it on stock tune with stock mufflers, typically when doing rev matches.
cyralax is offline   Reply With Quote
Reply

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
Forum Jump

All times are GMT -4. The time now is 01:48 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2018 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.