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Generation III Internal Engine
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Old 01-15-2002, 01:30 PM   #1
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Default backfires when letting off gas

usually my car will backfire and pop a little when i let off the gas... happens more often when i keep it in third. i leaned it out a little for WOT, should i lean out the idle maybe?
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Old 01-15-2002, 02:34 PM   #2
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Default Re: backfires when letting off gas

Are you talking a for-real backfire, or just a popping noise when you let off the gas? Some popping is quite normal on ANY car (aftermarket mufflers really bring this sound out). If you're hearing something that sounds like a shotgun firing though, then you could have a problem. If it's just a mild popping noise, I wouldn't hose with the mixture...

The only real way to tell if you're running too rich or too lean is to capture some AutoTap data. Cheers! <img src="graemlins/gr_cheers.gif" border="0" alt="[cheers]" />

[ January 15, 2002: Message edited by: Nightclaw ]</p>
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Old 01-15-2002, 02:39 PM   #3
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Default Re: backfires when letting off gas

I was backfiring so bad that I blew the bellows that connected the piping from the turbo to the throttle body into pieces 3 times.

Turned out to be a backed out spark plug.
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Old 01-15-2002, 02:43 PM   #4
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Default Re: backfires when letting off gas

Mine does it too!! It's been doing it for almost 2 years, and no problems yet!! <img src="gr_stretch.gif" border="0">
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Old 01-15-2002, 03:46 PM   #5
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Default Re: backfires when letting off gas

I get that problem all the time, I guess its just how you are with the gas pedal, It only happens once and a while...it gets the people though if im in a public place... <img src="gr_stretch.gif" border="0">
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Old 01-15-2002, 03:49 PM   #6
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Default Re: backfires when letting off gas

well, auto tap said that its all good at WOT <img src="gr_stretch.gif" border="0">

its not a large backfire, sometimes its more of a small backfire, then some burbling. i have longtubes, but a stock muffler. just as long as nothing bad is going on.
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Old 01-15-2002, 04:03 PM   #7
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Default Re: backfires when letting off gas

Open cutout Roy? Yeah that's normal.
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Old 01-15-2002, 07:32 PM   #8
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Default Re: backfires when letting off gas

Yeah mine also makes little popping noises. It's normal. Most people I have talked to say they like that noise.
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Old 01-15-2002, 08:27 PM   #9
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Default Re: backfires when letting off gas

Popping when you let off the throttle can come from three sources:

1) Your air injection pump is on (normal for first two minutes of a cold start). This is causing unburnt hydrocarbons to burn rapidly in your pipes = popping noise.

2) You have an exhaust leak and/or open cutout. See cause 1).

3) You are running a large cam and unspent fuel is passing through during overlap.

Anyone know of any others?

Also, I assume you mean exhaust backfire. Something in your intake manifold can be pretty serious since it's hard to do that on an EFI engine.

[ January 15, 2002: Message edited by: WeatherGuy ]</p>
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Old 01-15-2002, 10:16 PM   #10
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Default Re: backfires when letting off gas

Ah ha! I get popping when it has not warmed up yet. Cause 1. It always goes away..... <img src="gr_images/icons/wink.gif" border="0">
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Old 01-15-2002, 10:19 PM   #11
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Default Re: backfires when letting off gas

Yeah, you are running no cats so the fuel pops when burnt. I get it, I like it, it is like a guy. What kind of a guy does not fart or burb every once in a while, hehe! <img src="graemlins/gr_jest.gif" border="0" alt="[jester]" />
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Old 01-15-2002, 11:46 PM   #12
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Default Re: backfires when letting off gas

[quote]Originally posted by Pro Stock John:
<strong>Open cutout Roy? Yeah that's normal.</strong><hr></blockquote>

i havent run an open cutout on the street since the converter-just too loud when reving off the line. i do have the off road pipes on though <img src="gr_stretch.gif" border="0">

can you believe i got pulled over for loud exhuast out of a toll booth with this setup <img src="gr_eek2.gif" border="0"> I told the officer that the muffler was stock (which it is). i still got a written warning though. bastard cops.
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Old 01-16-2002, 11:55 AM   #13
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Default Re: backfires when letting off gas

I noticed that my car popped in the stock exhaust during deceleration with a cold engine. Now that have installed the Corsa system, the noise is a little louder. I have yet to drive with the new system and see how it is after warmup (car is off the road for winter). I think the thing is running rich until the O2s heat up and it goes into closed loop.
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Old 01-16-2002, 11:55 AM
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