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Old 01-28-2003, 11:08 PM   #1
DJ626
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Default Help!...constant backfiring....

I recently installed my up and down pipe, after, i noticed sometimes a loud pop noise would occur after letting of the gas and putting the car in nuetral. Ive heard of this before so it didnt bother me...however, now it happens every time i let off the gas and its really getting annoying.....any input is appreciated....thanks in advance.
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Old 01-28-2003, 11:35 PM   #2
cmaj7
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Default That's normal

What you are experiencing is afterfire, not backfire. A backfire is an explosion in the intake manifold.

If you have no cat's you will get afterfire. It's very common in turbo applications because the engine tends to run richer when on boost. Running rich adds an element of safety by cooling things down thus, reducing the likelihood of detonation(very very bad).

Afterfire is caused by a small amount of unburnt fuel which ignites when it hits oxygen in the exhaust. If you are running a non recirculating BOV it will excacerbate the situation. As will anything that makes the engine run richer.

The only way you will eliminate the sound of afterfire is run with a cat.

I, and many others here, actually love the pop sounds from afterfire as I downshift and brake.
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Old 01-28-2003, 11:37 PM   #3
krillz
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if you dont mind me asking, whats your exact inatake/exhaust setup?
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Old 01-28-2003, 11:37 PM   #4
DJ626
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Thanks....just wanted to make sure its normal as it has begun to occur more often....
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Old 01-29-2003, 12:36 AM   #5
krillz
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whats your exhaust set up?
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Old 01-29-2003, 08:36 AM   #6
rex n effect
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I have a cat, but i still get a muffled after-fire from time to time with a turboXS exhaust, especially before the cat is warmed up.
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Old 01-29-2003, 10:02 AM   #7
mlambert
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this is one of the perks of a turbo car
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Old 01-29-2003, 10:10 AM   #8
JayGold
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Currently catless TXS Stage 4= afterfires at 2,000rpm's all the time. The best is to be sitting at a light, blip the throttle, and hear the afterfire...while all the surrounding drivers look worried
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Old 01-29-2003, 11:49 AM   #9
thebusiness999
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Talking Useless post...

ALL HAIL THE AFTERFIRE, IT IS YOUR GOD!!!

Yes, I like my afterfire too...
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Old 01-29-2003, 04:34 PM   #10
whiterabbit
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i dont get much popping and i am running catless. Is there something wrong with my exhausts or something?

I want some popping
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Old 01-29-2003, 04:54 PM   #11
DJ626
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My set up is:
Helix down pipe
gruppe s up pipe
TXS BOV
Intake resonator mod
HKS carbon ti cat back
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Old 01-29-2003, 04:55 PM   #12
Eric SS
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Mine definetly started afterfiring after I installed my turbo and got a high flow cat. It is normal

Eric
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Old 01-29-2003, 09:12 PM   #13
Chunky_Chicken
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I experienced an increase in afterfiring after swapping to an Ultimate up-pipe and Bosal down-pipe. I'm also running a straight pipe.

I absolutely love the sound and can actually make it fire repeatedly while decellerating if I rapidly tap the gas pedal slightly around 3000RPM (just for fun ofcourse, it is pretty loud so I only do it in industrial areas). I had one fella ask me if I was running antilag!

-Pete
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Old 01-29-2003, 10:13 PM   #14
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i love this thread
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Old 01-29-2003, 10:52 PM   #15
DocDetroit
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Yes, I too am one of the people who was a little dissapointed with the afterfire I got when I went completely catless. It is not nearly enough! I love that sound.

I was driving behind a SRT-4 neon (manufacturer car driven by an engineer) and that thing had some vicious afterfire. I can't believe it comes from the factory with no mufflers! It sounds very good though. I talked to the guy, and he said it was a pre-production car, but it was very close to the production spec.

Does anyone know if I'll get more afterfire when I upgrade to STi injectors and a fuel pump? I imagine that when you jump off the throttle the ECU quits looking at the O2 sensor for fueling (because you're running like 24:1 A/F ratios at that point). So it must just use static injector pulse width values for the off-throttle state. If that's the case, bigger injectors should cause a richer off-throttle condition. Or am I way off base? Hmmm... I can't wait to test my theory
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Old 01-30-2003, 05:23 PM   #16
zacek
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getting a hybrid BOV such as the APS or the GFB will reduce the frecuency of those afterfires considerably.
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Old 02-02-2003, 02:05 PM   #17
whiterabbit
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when you guys say often...how often is often?
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Old 02-02-2003, 03:17 PM   #18
SFastWRX
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According to dictionary.com,

backˇfire
n.

1. An explosion of prematurely ignited fuel or of unburned exhaust gases in an internal-combustion engine.
2. The backward escape of gases or cartridge fragments when a gun is fired.
3. A fire started in the path of an oncoming fire in order to deprive it of fuel and thereby control or extinguish it

...

Source: The American HeritageŽ Dictionary of the English Language, Fourth Edition


...and...

No entry found for afterfire.


This event of unburnt fuel exploding in the exhaust has been called backfire since the internal combustion engine was invented. There are uncountable references to it in all manner of literature. I really have no idea where this "afterfire" term or the elitist attitude in its use came from, as I had never heard it before I registered for this board, although it sounds like a term they might use in the UK.

I did manage to get two useful hits (of the two hundred or so I scanned) in a google search, one being a reference to seeing the misnomer in a John Deere catalog, and this, from womenatthewheel.com's "Garage-ese 101":

Afterfire - the engine continues to fire after the vehicle has been turned off
Backfire - loud popping sound from the engine or tail pipe
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Old 02-02-2003, 08:39 PM   #19
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Quote:
. I really have no idea where this "afterfire" term or the elitist attitude in its use came from
Amen, to that.


Quote:
Afterfire - the engine continues to fire after the vehicle has been turned off
Let's hope they just keep calling this "run on " or " dieseling" as always, and not make up even more unnecessary and confusing words.
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Old 02-02-2003, 08:53 PM   #20
thebusiness999
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lol, that's kinda funny...

So who made up this afterfire term?
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