Why does my exhaust pop/Backfire?????
Thread Starter
Pro
Joined: Jan 2005
Posts: 670
Likes: 1
From: Vancouver BC
Why does my exhaust pop/Backfire?????
On my 98 with headers/no cats with x and Borla stingers. When ever the rpm drops it sometimes pops/backfires. (When it drops at a high rpm) Ive been told that there is about a 2 feet flame that shoots from my tips. I dont mind it or anything but im just wondering why this is and if it's causing any harm to my vette. 
Racer
Joined: Dec 2003
Posts: 258
Likes: 14
From: Santa Maria Ca.
They all do that when letting off the throttle below about 2500 RPM. With your stock exhaust, it's so quiet, that you can't hear it.
Above 2500 RPM, when you let off the throttle, you don't get backfires because the engine computer shuts off all fuel, until the RPMs approach the idle speed, then fuel is added again.
Now you can hear it with your louder exhaust system.
Above 2500 RPM, when you let off the throttle, you don't get backfires because the engine computer shuts off all fuel, until the RPMs approach the idle speed, then fuel is added again.
Now you can hear it with your louder exhaust system.
Safety Car
Joined: Oct 2004
Posts: 4,816
Likes: 132
From: Plano TX
Ever been to a NASCAR race?? Obviously not,, When the cars are approaching a turn coming off of a high speed straight they have to let off the throttle.. Lots of backfiring and a firework show out the pipes. I like it
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Joined: Jul 2007
Posts: 402
Likes: 7
From: Illinois
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Mine popped like crazy and occasionally shot flames for many years. (LT's no cats, X-pipe)
Since deleting the AIR system 2 years ago, it's never done it even once.
I can coast down from 6k rpm, and it's just smoooth.
And, running a cam with ~20* overlap, trust me there's no shortage of unburnt fuel passing through those pipes.
Nothing changed with my exhaust system during that transition, it's remained the same for the past 6 years, so the exhaust is not the culprit.
I've seen others say it, and based on my experience, I agree, it is the AIR system that causes the popping phenomenon.
Since deleting the AIR system 2 years ago, it's never done it even once.
I can coast down from 6k rpm, and it's just smoooth.
And, running a cam with ~20* overlap, trust me there's no shortage of unburnt fuel passing through those pipes.
Nothing changed with my exhaust system during that transition, it's remained the same for the past 6 years, so the exhaust is not the culprit.
I've seen others say it, and based on my experience, I agree, it is the AIR system that causes the popping phenomenon.
Instructor
Joined: Jul 2008
Posts: 101
Likes: 0
From: Austin, TX
St. Jude Donor '08
Mine popped like crazy and occasionally shot flames for many years. (LT's no cats, X-pipe)
Since deleting the AIR system 2 years ago, it's never done it even once.
I can coast down from 6k rpm, and it's just smoooth.
And, running a cam with ~20* overlap, trust me there's no shortage of unburnt fuel passing through those pipes.
Nothing changed with my exhaust system during that transition, it's remained the same for the past 6 years, so the exhaust is not the culprit.
I've seen others say it, and based on my experience, I agree, it is the AIR system that causes the popping phenomenon.
Since deleting the AIR system 2 years ago, it's never done it even once.
I can coast down from 6k rpm, and it's just smoooth.
And, running a cam with ~20* overlap, trust me there's no shortage of unburnt fuel passing through those pipes.
Nothing changed with my exhaust system during that transition, it's remained the same for the past 6 years, so the exhaust is not the culprit.
I've seen others say it, and based on my experience, I agree, it is the AIR system that causes the popping phenomenon.
How does one go about the AIR delete mod? Is there a DIY thread somewhere?
Le Mans Master
Joined: Jul 2013
Posts: 5,699
Likes: 147
Mine had a silent exhaust leak on one of the longtubes.
When I replaced the clutch they re and re the headers with new gaskets and no more popping....
When I replaced the clutch they re and re the headers with new gaskets and no more popping....
Last edited by StrangelovesM6Vert; May 26, 2017 at 09:37 AM.