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Old 02-15-2001, 02:38 PM   #1
subee_love
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Join Date: Feb 2001
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01 Impreza
BRP

Exclamation Backfire Problem!

Ok, here is my situation;01 Impreza RS, Brospeed muffler and mid-pipe, removed silencer on stock intake, have reset ECU. I am getting a single "pop" backfire, sometimes two, when I let off on the gas. This happens at about, 2.5 to 3.5K RPM's, also sometimes when I shift gears! It does't happen at high RPM's, just the low range. Is this a problem I should take up with the Dealer, or is this just because of the mods I have done?! Any help on this would be greatly welcome. Thanks, Shawn
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Old 02-15-2001, 02:46 PM   #2
Subie Gal
GC84Ever
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Chapter/Region: NWIC
Location: WA
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1970 FF-1 & '70 Van
02 WRX/01 RS

Post

happens w/any modded exhaust "i think"

used to happen on my GT w/my old set up..

and now on my RS w/the Scoobysport...

think it's pretty common and nothing to stress out about... i am no tech head as far as exhausts go tho.. i know someone here will have the explanation as to "why" it happens....

j.
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Old 02-15-2001, 02:49 PM   #3
remarcable
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Backfires are fun, especially when you can get the vehicle to do it on queue.

I remember back in elementary school our soccer team had a beat up old ford van that we went to all our games in that would backfire on high acceleration. Our coach would do it right next to people on the sidewalk, he made one crackhead fall off his rusty bicycle. It was funny, we laughed.

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Old 02-15-2001, 02:51 PM   #4
Lord-Atak
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My rs used to do it alot. Now only in cold weather about 3000rpm
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Old 02-15-2001, 03:04 PM   #5
Duva
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I can't find the other thread on this, but I think it has to do with a slight delay (when you let off the gas) between the throttle closing up and the injectors injecting less fuel. If this is true, then there is still the higher level of fuel coming in to a cylinder once or twice without all the extra air needed to burn it. The extra unburned fuel is pushed out into the exhaust where it contacts the hot headers. It explodes on contact causing the popping you hear. I think the other thread said this is very common, but the stock exhaust is super-effective and muffles it out.

Wow... I just reread that. I hope it makes some sense. Someone please correct me if I'm wrong.
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Old 02-15-2001, 03:10 PM   #6
SanjuNana
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You'er fine ... here's another thread that discussed the backfires (this one has a little more tech info on why the backfire is occurring).
http://www.i-club.com/ubb-files/Forum1/HTML/018695.html
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Old 02-15-2001, 03:52 PM   #7
RotrPwr
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Also could be that the modifications you have performed have caused your engine to run a little rich in the rpm range you mentioned. Sometimes a rich running engine will backfire. If this were the case there isnt much you can do to remedy this short of buying a AFC and trimming the fuel curve a little in the midrange. Of course you could always advance the timing a bit but that is not suggested since advancing the timing effects the entire rpm range and i bet your engine is running spot on on top, which advancing the timing would cause your engine to burn lean on the topend(read: detonation). Just a suggestion though.

Darril
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Old 02-15-2001, 04:18 PM   #8
thepas
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Post

it's NORMAL, the car runs rich. Get used to it or get a Fuel controller and lean the car out a little.

Kyle
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Old 02-15-2001, 04:23 PM   #9
Lord-Atak
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Also forgot to ask why you think its a problem. I personaly like it.
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Old 02-15-2001, 04:44 PM   #10
subee_love
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Was just a little perplexed. I kinda like it myself as well. I'm glad it's not hurting anything!! Thanks for ALL the input
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Old 02-15-2001, 06:25 PM   #11
Kissifur
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its just because the exhuast flows more freely. its like breathing out through your mouth compared to breathing out through a straw...
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Old 02-15-2001, 08:13 PM   #12
CosmoTheCat
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Mine does it with stock exhaust. I like it.

Quote:
Backfires are fun, especially when you can get the vehicle to do it on queue.
Kinda reminds me of 'Uncle Buck'
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Old 02-15-2001, 11:09 PM   #13
Freeskier
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2011 STi

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Mine does it with stock exhaust too but I hear it coming from the front of me on the right hand side (like just in front of the passenger)
Isn't it supposed to come from the back???

Stefan
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Old 02-15-2001, 11:45 PM   #14
meebs
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Stefan, exact same thing with me too. The only thing i have done is remove the silencer.... but it was there with the silencer on also. It sounds like it's coming from under the bonnet rather than the back... I've never been on the outside of my car though as it went by... so I don't know what it sounds like out of the car.

-Mitch
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Old 02-16-2001, 04:23 AM   #15
ivbdn
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Aspen White

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Nothing to worry about. Mine backfires and I too enjoy it.
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