Is backfiring a good thing or a bad thing?

rAdzM · 11-01-2009, 01:44 PM

And why?

Thanks!
-radz

FStop7 · 11-01-2009, 02:36 PM

it's what V8s do

leeor · 11-01-2009, 03:59 PM

hahha my gas scooter used to back fire a lot

Green///Hell · 11-01-2009, 04:15 PM

Its awesome thats what it is and I get it all the time.

Especially when driving under a bridge and the pops scare people

bobbyd1961 · 11-01-2009, 04:46 PM

huh? not a good thing and it never happened to me. bring it in

GT3 Tim · 11-01-2009, 05:22 PM

BOOM = bad

pop = ok/normal

foosh · 11-01-2009, 06:46 PM

Quote:

Originally Posted by GT3 Tim

BOOM = bad

pop = ok/normal

I prefer to call a "burble" OK. Everything else is bad. Aren't semantics wonderful?

davedave · 11-01-2009, 06:49 PM

Good = Cool
Bad = Pull over instantly if popo saw it / fuel map too rich

Lemans_Blue_M · 11-01-2009, 07:45 PM

Catless exhaust system + AFR's too rich = backfire

or

A backfire situation can occur when there is a small leak in the air injection system that feeds the exhaust system. This can cause unburned fuel in the exhaust pipe to explode. A stuck or faulty air intake or gulp valve near the exhaust manifold can cause this to happen.

BTW: A 'gulp' valve will sense a change of vacuum in the intake manifold. The gulp valve is intended to stop the air flow over the exhaust valves when a rich mixture is added to the system. (whenever you let up on the gas pedal) If the gulp valve does not operate correctly, then this rich mixture would hit the exhaust manifold with the forced air, causing it to explode in the exhaust system. The intensity of the explosion will depend on a number of factors.

darkseid2k · 11-01-2009, 08:44 PM

I personally like it with my catless system.. it's mainly controllable when I want to have it done.

Periokid · 11-01-2009, 08:50 PM

I hope its nothing like this...

http://vids.myspace.com/index.cfm?fu...deoID=42033385

SV Concepts · 11-01-2009, 09:51 PM

I backfire every time I pull out of the parking lot. Yeah, I'm a badarse.

rAdzM · 11-06-2009, 10:57 AM

do you guys know which gear and which rpm does the backfire? or does it depends?

Subw00er · 11-06-2009, 11:40 AM

its good cause it sounds awesome. I wish my car did it more - I just get one or two little pops when its cold. My vette did it quite a bit and my bike does it as well. I love the sound.

getlucky · 11-06-2009, 02:53 PM

It's ok you just cleaning the carbon off the valves, My Harley does it all the time , with blue flames

gthirtyfizle · 11-06-2009, 03:07 PM

With my remus race and catless it sounds sick. I love it when it happens.

JCtx · 11-06-2009, 03:23 PM

Just don't confuse backfire with afterburn

. The former is loud enough to scare most folks, and requires A/F ratios easily triggering a CEL. In fact, backfiring is unheard of with fuel injection. Good day.

kmac1980 · 11-06-2009, 03:34 PM

The e9x m3 gives off an exhaust pop even with the stock exhaust system, when you let off the gas (without shifting gears) at around 3-4K rpms, although you won't hear it much as the stock muffler does a good job of deadening this (i used to hear it sometimes with the top down only)

With an aftermarket catback exhaust, you'll hear this much more audibly as the muffler is freer flowing. With a catless x-pipe it would be even more pronounced...

Now if you're really cool, you could do what these bikers in London do:

11-01-2009, 01:44 PM	#1
rAdzM Smashed! 84 Rep 1,309 Posts Drives: 2009 E92 M3 Join Date: Oct 2008 Location: Socal iTrader: (11) Garage List 2009 BMW M3 [10.00] 2006 BMW M5 [9.00]	Is backfiring a good thing or a bad thing? And why? Thanks! -radz __________________ est. 2008 BBS \| BREMBO \| RECARO \| ig: @euro_rad
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11-01-2009, 02:36 PM	#2
FStop7 I like cars 329 Rep 5,052 Posts Drives: M6 Join Date: Oct 2008 Location: Newbury Park, CA iTrader: (3)	it's what V8s do __________________ My photostream: http://www.flickr.com/photos/racelap/
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11-01-2009, 03:59 PM	#3
leeor Banned 138 Rep 2,386 Posts Drives: 2010 Blue Prius III Join Date: Mar 2009 Location: Los Angeles iTrader: (4)	hahha my gas scooter used to back fire a lot
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11-01-2009, 04:15 PM	#4
Green///Hell Colonel 183 Rep 2,872 Posts Drives: 991 GT3, F15 X5, 1199S Join Date: Feb 2009 Location: Chicago iTrader: (5)	Its awesome thats what it is and I get it all the time. Especially when driving under a bridge and the pops scare people
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11-01-2009, 04:46 PM	#5
bobbyd1961 Banned 43 Rep 2,406 Posts Drives: 2009 M3 sedan LeMans Blue Join Date: Jun 2009 Location: new jersey iTrader: (0)	huh? not a good thing and it never happened to me. bring it in
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11-01-2009, 05:22 PM	#6
GT3 Tim Moderator 94 Rep 1,920 Posts Drives: 2014 MB E63S Join Date: Feb 2008 Location: Sacramento, CA iTrader: (0)	BOOM = bad pop = ok/normal __________________ Tim <--- apparently likes "3" cars 2014 E63S -- The Rocket 2014 F30 328i -- Kids car 2008 E90 M3 -- Sold 2004 GT3 -- Sold 1997 M3/4 -- Sold 1995 M3 -- Sold
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11-01-2009, 06:49 PM	#8
davedave Captain 40 Rep 788 Posts Drives: Godzilla Join Date: Jul 2007 Location: Somewhere iTrader: (7)	Good = Cool Bad = Pull over instantly if popo saw it / fuel map too rich
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11-01-2009, 07:45 PM	#9
Lemans_Blue_M Automotive Industry Insider 462 Rep 1,948 Posts Drives: Lemans Blue M3 Join Date: Aug 2007 Location: Texas iTrader: (0)	Catless exhaust system + AFR's too rich = backfire or A backfire situation can occur when there is a small leak in the air injection system that feeds the exhaust system. This can cause unburned fuel in the exhaust pipe to explode. A stuck or faulty air intake or gulp valve near the exhaust manifold can cause this to happen. BTW: A 'gulp' valve will sense a change of vacuum in the intake manifold. The gulp valve is intended to stop the air flow over the exhaust valves when a rich mixture is added to the system. (whenever you let up on the gas pedal) If the gulp valve does not operate correctly, then this rich mixture would hit the exhaust manifold with the forced air, causing it to explode in the exhaust system. The intensity of the explosion will depend on a number of factors. __________________ The best is yet to come...
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11-01-2009, 08:44 PM	#10
darkseid2k Private First Class 13 Rep 153 Posts Drives: '10 E71, '11 E92 Join Date: Dec 2008 Location: Toronto, ON iTrader: (0) Garage List 2008 E90 M3 [0.00]	I personally like it with my catless system.. it's mainly controllable when I want to have it done.
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11-01-2009, 08:50 PM	#11
Periokid First Lieutenant 61 Rep 335 Posts Drives: 2015 F80 M3 Join Date: Apr 2009 Location: LI, NY iTrader: (0)	I hope its nothing like this... http://vids.myspace.com/index.cfm?fu...deoID=42033385
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11-01-2009, 09:51 PM	#12
SV Concepts 361 Rep 5,859 Posts Drives: Vorsteiner E60 M5 Join Date: Mar 2006 Location: 1460 White Oaks Rd. Suite F. Campbell, CA 95008 iTrader: (10)	I backfire every time I pull out of the parking lot. Yeah, I'm a badarse.
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11-06-2009, 10:57 AM	#13
rAdzM Smashed! 84 Rep 1,309 Posts Drives: 2009 E92 M3 Join Date: Oct 2008 Location: Socal iTrader: (11) Garage List 2009 BMW M3 [10.00] 2006 BMW M5 [9.00]	do you guys know which gear and which rpm does the backfire? or does it depends? __________________ est. 2008 BBS \| BREMBO \| RECARO \| ig: @euro_rad
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11-06-2009, 11:40 AM	#14
Subw00er Bates '08 Interlagos Launch 126 Rep 1,230 Posts Drives: 440i xGC, ZL1, JCW Join Date: Nov 2005 Location: NY iTrader: (2)	its good cause it sounds awesome. I wish my car did it more - I just get one or two little pops when its cold. My vette did it quite a bit and my bike does it as well. I love the sound. __________________ Custom Exhaust Project: Bates Valvetronic exhaust: http://www.m3post.com/forums/showthread.php?t=253661 -- Exhaust Mod pics in here: http://www.flickr.com/photos/40236795@N03/ DON'T BUY Race Ready Performance electronic cutout valves. Here's why: http://www.m3post.com/forums/showthr...40#post9589740
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11-06-2009, 02:53 PM	#15
getlucky Second Lieutenant 37 Rep 259 Posts Drives: 2009 M3 Sedan Join Date: Mar 2009 Location: Everywhere iTrader: (1)	It's ok you just cleaning the carbon off the valves, My Harley does it all the time , with blue flames
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11-06-2009, 03:07 PM	#16
gthirtyfizle Colonel 191 Rep 2,867 Posts Drives: E92 M3 AW Join Date: Jul 2008 Location: NYC iTrader: (4)	With my remus race and catless it sounds sick. I love it when it happens.
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11-06-2009, 03:23 PM	#17
JCtx Major General 258 Rep 5,012 Posts Drives: No BMW yet Join Date: May 2008 Location: El Paso TX iTrader: (0)	Just don't confuse backfire with afterburn . The former is loud enough to scare most folks, and requires A/F ratios easily triggering a CEL. In fact, backfiring is unheard of with fuel injection. Good day.
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11-06-2009, 03:34 PM	#18
kmac1980 Major 36 Rep 1,039 Posts Drives: '19 540xi Join Date: Jan 2006 Location: toronto iTrader: (1)	The e9x m3 gives off an exhaust pop even with the stock exhaust system, when you let off the gas (without shifting gears) at around 3-4K rpms, although you won't hear it much as the stock muffler does a good job of deadening this (i used to hear it sometimes with the top down only) With an aftermarket catback exhaust, you'll hear this much more audibly as the muffler is freer flowing. With a catless x-pipe it would be even more pronounced... Now if you're really cool, you could do what these bikers in London do:
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