Why would a car "backfire"??
Thread Starter
Safety Car
Joined: Oct 2000
Posts: 3,654
Likes: 0
From: Downtown Chicago IL
Re: Why would a car "backfire"?? (Buckmaster)
Hmm, I'm guessing it would backfire if there was unburnt fuel reaching the exhaust...not enough air, but too much fuel maybe. Not sure....I'm not too technical.
Hey, that new sig pic looks nice. Reminds me of my car + euro tail lamps! :D
Hey, that new sig pic looks nice. Reminds me of my car + euro tail lamps! :D
Burning Brakes
Joined: Feb 1999
Posts: 831
Likes: 0
From: Austin TX
Re: Why would a car "backfire"?? (O-Ace)
That's usually gonna be the right answer. Usually it's because you're running rich and there's unburned fuel reaching the exhaust. Have you gutted / removed your cats?
Burning Brakes
Joined: May 2001
Posts: 790
Likes: 0
From: Raleigh, NC
Re: Why would a car "backfire"?? (Buckmaster)
Is it colder there today than it has been? Mine has been popping more now that it is colder.
Looking at your mods I'm amazed you haven't heard this before. My Z pops a lot, even with the X-pipe.
[Modified by NetJunkie, 6:22 PM 11/14/2001]
Looking at your mods I'm amazed you haven't heard this before. My Z pops a lot, even with the X-pipe.
[Modified by NetJunkie, 6:22 PM 11/14/2001]
Burning Brakes
Joined: May 2001
Posts: 790
Likes: 0
From: Raleigh, NC
Re: Why would a car "backfire"?? (Buckmaster)
With your mods I think it is *VERY* normal. Popping with aftermarket exhaust happens a lot...headers make it even louder. If you want to soften it some try an x-pipe. That got rid of some of my popping, but then headers made some come back.
I'm not in love with it, but I'm used to it now. I've heard it on a lot of diff Vettes with aftermarket exhausts.
I'm not in love with it, but I'm used to it now. I've heard it on a lot of diff Vettes with aftermarket exhausts.
Race Director
Joined: May 2000
Posts: 14,542
Likes: 5
Re: Why would a car "backfire"?? (NetJunkie)
buckmaster:
6 posts in one hour -- sounds like you're worried and it's important.
The backfire comes from the colder weather which means richer unburnt mixture.
No worries, it's normal. Better rich than ...
:smash:
[Modified by EHS, 6:56 PM 11/14/2001]
6 posts in one hour -- sounds like you're worried and it's important.
The backfire comes from the colder weather which means richer unburnt mixture.
No worries, it's normal. Better rich than ...
:smash:
[Modified by EHS, 6:56 PM 11/14/2001]
Melting Slicks
Joined: Feb 2000
Posts: 2,724
Likes: 41
From: Liberty Hill Texas
Re: Why would a car "backfire"?? (Buckmaster)
After this happening on the 99 the tuners all said it was puddling of fuel in the pre 2001 intake but you have a 2001 and they all have the LS6 or Z06 intake. Makes me wonder!
Melting Slicks
Joined: Feb 2000
Posts: 2,724
Likes: 41
From: Liberty Hill Texas
Re: Why would a car "backfire"?? (Buckmaster)
Buckmaster,
It only happened on the 99 once and we had been "having some fun" on the Parkway near Eatontown NJ and we got off waiting on a friend and when I restarted the car "Pow" and that got me to talking to a lot of guys who do the Vette Dr's and CARTEK and the word puddling came up. It scared the Crap out of me but when I cranked the motor again all was fine. I have an butt load of mods on the motor so maybe your AIR/Fuel needs looking @! Mine has never done it since! :cheers: :flag
It only happened on the 99 once and we had been "having some fun" on the Parkway near Eatontown NJ and we got off waiting on a friend and when I restarted the car "Pow" and that got me to talking to a lot of guys who do the Vette Dr's and CARTEK and the word puddling came up. It scared the Crap out of me but when I cranked the motor again all was fine. I have an butt load of mods on the motor so maybe your AIR/Fuel needs looking @! Mine has never done it since! :cheers: :flag
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Mar 1999
Posts: 6,744
Likes: 1
From: delmont pa
Cruise-In I Veteran
Cruise-In II Veteran
Re: Why would a car "backfire"?? (Buckmaster)
check your exhaust for leaks as this will let air into the exhaust and cause the backfire.
[Modified by clem zahrobsky, 9:00 PM 11/14/2001]
[Modified by clem zahrobsky, 9:00 PM 11/14/2001]
Safety Car
Joined: Jan 2000
Posts: 4,965
Likes: 0
From: Midlothian, VA
Re: Why would a car "backfire"?? (Buckmaster)
Buckmaster, here's "backfire" from my ASE Certification manual:
Backfire - is caused by the air-fuel mixture igniting in the intake manifold or exhaust system. A loud BAND or POP sound can be heard when the mixture ignites.
Backfiring can be caused by incorrect ignition timing, crossed spark plug wires, cracked distributor cap, bad carburetor accelerator pump, exhaust system leakage, faulty air injection system or other system fault.
Maybe that can steer you toward a solution :)
Backfire - is caused by the air-fuel mixture igniting in the intake manifold or exhaust system. A loud BAND or POP sound can be heard when the mixture ignites.
Backfiring can be caused by incorrect ignition timing, crossed spark plug wires, cracked distributor cap, bad carburetor accelerator pump, exhaust system leakage, faulty air injection system or other system fault.
Maybe that can steer you toward a solution :)
Safety Car
Joined: Jan 2000
Posts: 4,965
Likes: 0
From: Midlothian, VA
Re: Why would a car "backfire"?? (Buckmaster)
Buckmaster, it could be your TTS program. The A/F and timing could be outta wack with the decrease in ambient temps. I would check the exhaust first. Do you have autotap? You could get some runs with it and see where you LTFT and Timing is. :seeya
Advanced
Joined: Jun 2001
Posts: 91
Likes: 0
Re: Why would a car "backfire"?? (C5Noir)
Does the engine feel a little rougher? Mine was backfiring every once and awhile and running rough. I took it to the dealership, turns out it was a bad spark plug causing misfirings.
Tom
PS. This started at about 13000 miles.
Tom
PS. This started at about 13000 miles.
Burning Brakes
Joined: Feb 1999
Posts: 933
Likes: 0
From: Santa Clara Ca
Re: Why would a car "backfire"?? (C5Noir)
Buckmaster, it could be your TTS program. The A/F and timing could be outta wack with the decrease in ambient temps. I would check the exhaust first. Do you have autotap? You could get some runs with it and see where you LTFT and Timing is. :seeya
Racer
Joined: Nov 2000
Posts: 335
Likes: 0
From: Effingham, IL IL
Re: Why would a car "backfire"?? (Buckmaster)
I have had plug wire burns an number of times, after 20K miles I have remedied the situation. Sometimes the first indicator of an early burn is backfiring, the next thing I ussually notice is poor performance from 1500- 1700 RPMs
Good luck
Greg
Good luck
Greg
Melting Slicks
Joined: Dec 1999
Posts: 3,020
Likes: 0
From: Union City CA
Re: Why would a car "backfire"?? (Buckmaster)
I wonder how "loud" this backfire is. I have heard some that sound like gunshots. Mine always gurgles but not pops unless I slow down by being in a low gear on the auto. You mean that sort of sound?
My guess I would buy the autotap (or whatever utility) and get some recordings.
Speed-Racer
My guess I would buy the autotap (or whatever utility) and get some recordings.
Speed-Racer
Burning Brakes
Joined: Feb 1999
Posts: 933
Likes: 0
From: Santa Clara Ca
Re: Why would a car "backfire"?? (Buckmaster)
Being that changing the PCM code was the last changes you did, dumped PCM NVram and RAM, causing the engine management to go through a relearn process, it now might show the AFR is not what you want.
We can guess but the best path is to hook up a PCM scanner and see exactly how the fuel trims, timing, knock etc look like and if there is any pending DTCs hiding out.
Also via scanner, run the I/M tests results function and see if emissions are in a passed completed state.
EPA wants to protect the cats, thus backfires are not wanted and thus that condition will cause PCM to protect cats by detuning to prevent more backfiring from doing damage to cats.
The scanner would allow you to have hard facts as what all 4 O2s are reporting and downstream ( after cats) 02s should on cold start clearly show lower mVolts then their upstream partner since Cats output O2.
[Modified by team-zr1, 2:46 PM 11/16/2001]
We can guess but the best path is to hook up a PCM scanner and see exactly how the fuel trims, timing, knock etc look like and if there is any pending DTCs hiding out.
Also via scanner, run the I/M tests results function and see if emissions are in a passed completed state.
EPA wants to protect the cats, thus backfires are not wanted and thus that condition will cause PCM to protect cats by detuning to prevent more backfiring from doing damage to cats.
The scanner would allow you to have hard facts as what all 4 O2s are reporting and downstream ( after cats) 02s should on cold start clearly show lower mVolts then their upstream partner since Cats output O2.
Buckmaster, it could be your TTS program. The A/F and timing could be outta wack with the decrease in ambient temps. I would check the exhaust first. Do you have autotap? You could get some runs with it and see where you LTFT and Timing is. :seeya
Bingo ... and the cat protection of EPA functions in PCM is not going to like it, rich is a no no to cats.
Team ZR1
Not sure I understand your point, can you please elaborate? My cats are still on the car. Today, it happened then went away and has not returned. Please explain to me. Thanks :)
Bingo ... and the cat protection of EPA functions in PCM is not going to like it, rich is a no no to cats.
Team ZR1
Not sure I understand your point, can you please elaborate? My cats are still on the car. Today, it happened then went away and has not returned. Please explain to me. Thanks :)
[Modified by team-zr1, 2:46 PM 11/16/2001]
