Exhaust makes 'popping' noise when i let off the gas

I have flow masters and when i'm like easing off the gas or going down a hill while leaving it in gear the exhaust makes a loud popping noise like their is combustion on every few rpms.
I have flowmasters on it. What could it be?

Mine does the same thing sometimes.

do you have custom muffler or stock?

flo master

My guess is that its just the way the chamber for the exhaust is. Mine stock never did it till i got the flowmaster on it

wonder if any other 6'ers have same problem with it, you have 3.8 right?

no 5.7 ls1

....so you say....

jp..

Hmm maybe its flo masters design? do you have 2.5" or 3"?

I think its 2.5in I dont remember. But i do agree i think it is flowmasters design of the chamber that causes the as geno would put it the pooping sound

its normal mines doe it as well i dont like it though at all, thats why im changing it soon.

Philly what are you going to get?

My Magnaflow does it I believe it's from loss of [some] backpressure, i have 3". I know loudmouths can do it too on LS1s at least.

is it a pop or a crackle? because mine is more of a crackle....

is it a pop or a crackle? because mine is more of a crackle....

nice double post
mines like a series of popping if im accelerating heavy and let right off

Just means some gas got past the headers and cats and is not igniting till way back in the exhaust. Mine doesn't do it unless i was just on the gas reall heavy.

Im glad someone else asked this question. I just installed headers and a a 3" flowmaster and mine does the exact same thing. Popping after hard excelleration. I thought I screwed something up or found another problem.

my car does that too. i have a 2.8 6cyl....... with flo masters, everything is stock except the flow masters, but it only pops when its not warmed up, sometimes if i downshift, but like you guys said if its unburned fuel getting to the cats or muffler, think its bad spark plugs, wires, and cap and rotor?

Nah stuff like this happens after hard acceleration cause u are pulling in all this fuel then u suddently cut it off so some of it will get through.

nice double post
mines like a series of popping if im accelerating heavy and let right off
i only hit the button once... so af must have wanted to get my question across to you all....

im thinking hooker for headers and borla for the exhaust

Hookers are ok, they have to be clean tho

yeah and at the same time its not my final answer, im still looking at other headers to see whats going to give me the most for my dollar, but borla is going on thats a no-brainer.

Um... where did you find hooker headers for the 3.8?!
I thought we were limited to CIA, Pacesetter and RKSport

the popping noise is from a lack of backpressure. all the vaccumm lines and emmission control stuff under the hood is set up for the stocl car specs. when you put headers or aftermarket exhaust you change the flow rate of the exhaust and that results in lesss back pressure causing the popping.

I will update on if is goes away when I get HPTuners done which will hopefully be this coming weekend

im not sure about all the others except for lt1 but expecially the thirdgen, this doesnt apply to...

the poping is from something like extra gas that isnt burned after letting off the pedal. i dont know about the technical side of it but the way i helped reduce it to the point that i can not notice it on my lt1 is i disabled the air pump.

the air pump puts air into the exhaust to get rid of moisture i beilive. disableing this doesnt hurt anything at all and can be disabled on an lt1 by disconecting the cable right under the air pump in front of the engine, close to optispark. it will have a purple connector on one side...

im not positive but i think the air pump comes on the first 4 mintues of engine run time and then every time you let off the gas hard.

regardless after unplugging the air pump the thing revs down sounding smooth and all... no poping or cracking...

it has nothing to do with backpressure, and getting the headers and freeer flowing exhaust only makes it worse...

im not sure about all the others except for lt1 but expecially the thirdgen, this doesnt apply to...

the poping is from something like extra gas that isnt burned after letting off the pedal. i dont know about the technical side of it but the way i helped reduce it to the point that i can not notice it on my lt1 is i disabled the air pump.

the air pump puts air into the exhaust to get rid of moisture i beilive. disableing this doesnt hurt anything at all and can be disabled on an lt1 by disconecting the cable right under the air pump in front of the engine, close to optispark. it will have a purple connector on one side...

im not positive but i think the air pump comes on the first 4 mintues of engine run time and then every time you let off the gas hard.

regardless after unplugging the air pump the thing revs down sounding smooth and all... no poping or cracking...

Well good thing that this worked for you, but FYI V6's don't have the air pump [when is for emissions] , so how is it the air when me, Xenostalgia and philly rs have 3.8's????

it has nothing to do with backpressure, and getting the headers and freeer flowing exhaust only makes it worse...

That is what we call a contradiction, buddy... gettign the headers and freer flowing exhaust reduces backpressure.

That is what we call a contradiction, buddy... gettign the headers and freer flowing exhaust reduces backpressure.



The exhaust has nothing to do with the source of the popping/cracking, but it only makes it more noticable as the restriction in the exhaust is less and it gets louder.

and about the 3.8's that why i said i wasnt sure for anything except the lt1...

EDIT:

i was looking on other forums and it looks like you guys are on your own, i havent seen anything about the 3.8 having that happen... good luck...

which other forums?

Like i said before its fuel that got past the cats and doesn't ignite untill its in the exhaust some where. LET'S SAY IT TOGEHTER PEOPLE "BACKFIRE" u got it "BACKFIRE".

.. the forums where half the people know what their talking about(no offense to anyone posting into this topic)... lt1tech.com and camaroz28.com

this is not a unique situation, and it is not unique to flowmaster. i sumise that you can hear it more clearly with flowmaster cause they work harder at getting sound through the mufflers. just about any exhaust has this effect tho.

its caused by excess fuel in the exhaust burning off. when you are WOT the comp is dumpin fuel in, then you almost instantly go to less than 10% throttle, cutting the air flow. excess fuel gets through the exhaust valves and burns off causing the crackle/pop (no snap though). this is an effect of BOTH low backpressure AND wide open throttle. the reduced back pressure allows the gas to escape further down stream, and the rich condition is caused by goin from WOT to idle near-instantly.

Thanks ChevyRacin, that is very helpful. :) Just making sure there isn't a dying whoopee cushion in my flowmasters.

hey 97 rs i wasnt aware that hooker dont make headers for a 3.8 guess i wont be using that then that sucks everyone else i know suggested i go with them guess ill have to go another rout, and did that other dude just insult us on a d. l.? i dont think anyon ein here claimed to be a gm tech if we were we wouldnt be in here sharing info like we do, just because some other group of guys didnt go through what we may have doesnt make us wrong, and im not putting down anyone else who has flow master because like i said i have them also i just think they suck ass, "i think" was the key some cars they mesh with others they done, i just happen to have a car that it dont, they restrict air flow if u ask me so if u cant swallow what we are saying or think then nobody is holding a gun to your head and making u post here, get my point?

Well I think the thread starter has recieved alot of different opinions and everyone has gotten there last word in. So I will add mine and locker her up.

Yes there are alot of other F-body forums on the internet that have very knowledgable member's and may know something that someone on AF may not know but we also have many very very knowledgable members, infact we have techs who are member's and we are the largest member based Auto forum on the net. Thats alot of different opinions on the situtation that may be able to help. I myself have seen techs and shops owner come to this forum asking for our opinion on problems and have recieved info even they didn't know. That is saying something.

Now if anyone doesn't like it here or thinks that none of us can possibly offer any assistance to you cause we don't know what we are talking about. Feel free to leave and never come back I don't know of any gun men ever forcing anyone to stay but I will research it some more.