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Rough deceleration with pop from exhaust?

This is a discussion on Rough deceleration with pop from exhaust? within the General Help forums, part of the LSx Technical Help Section category; Not sure if this is normal, or if this is an issue that has been brought up before. It's a ...

  1. #1
    Member onetroubledguy's Avatar
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    Rough deceleration with pop from exhaust?

    Not sure if this is normal, or if this is an issue that has been brought up before. It's a bit hard to explain but I'll do my best and hopefully it makes sense.

    After getting up past 60mph, if I let go of the gas and just coast, my car seems to have a rough time decelerating (you can hear and feel it). While this is happening, If I tap on the gas (just open it up, don't even give it anything if that makes sense) it will make a couple of popping sounds from the exhaust and will behave normally until I let go again. This only seems to happen at higher speeds, not in low gears.

    Any ideas?

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    Formula Driver! 96Firebirdformula's Avatar
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    Quote Originally Posted by onetroubledguy View Post
    Not sure if this is normal, or if this is an issue that has been brought up before. It's a bit hard to explain but I'll do my best and hopefully it makes sense.

    After getting up past 60mph, if I let go of the gas and just coast, my car seems to have a rough time decelerating (you can hear and feel it). While this is happening, If I tap on the gas (just open it up, don't even give it anything if that makes sense) it will make a couple of popping sounds from the exhaust and will behave normally until I let go again. This only seems to happen at higher speeds, not in low gears.

    Any ideas?
    Stock Exhaust??

  3. #3
    down with the lot lizards blackhawk01's Avatar
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    stock exhaust can be a cause of this...also...get someone to check your tune...i had this happen to me and got someone to check my tune...the person before me screwed my tune up BAAAAD...got that fixed...still pops...but as bad..well..not hardly at all, but a little..because of the stock exhaust....

    change that ORY!!!

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    Could be a little unburnt fuel when you let off the gas?

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    Senior Member TransAm11973's Avatar
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    do you have cats installed?

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    Senior Member Wheeler99WS6's Avatar
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    Sounds like common back pressure pop. If you have no cats I would say it is common unless you find the rough deceleration to be to rough you can try and retune your car. Now if you have cats then of course it is not common. Post your modifications and mileage so we can try to better help diagnose your problem.

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    Member onetroubledguy's Avatar
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    Thanks guys. Sorry for not being more detailed.

    I know that I have dual exhaust with cutouts but anything beyond that is unknown. I would also like to mention that this did not happen the first month and a half that I had the car (bought in August of this year). It has about 81k on it.

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    Member onetroubledguy's Avatar
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    For anyone interested...from another forum:

    slight popping on an LT1 or LS1 is normal when you rev up the engine high and then just let off. It is the exhaust pulse stack up inside the thubes and muffler that get slightly interupted by gassing it and thenletting off quick. It is even more noticable in cars with GUTTED cats because the cat makes an empty chamber (unless you sleeve it) and then the exhaust gasses gets trapped in the cat and cause even more turbulance.

    This can actually hurt scavangeing on your next cycle.

    I have driven about 20 of these F-bodies over the years andbeen on a ton more and they all pop a bit warmed up or not when you rev it up fast and just let off.

    You can really make a car do it if you are in like 3rd and get the revs up then down shift to 2nd. The engine trys to slowdown and the car will pop a bit.

    I have discussed this with Flowmaster reps, Borla reps and a few race engine builders. They all said it is normal to some extent. NOW there is a HUGE difference between a little poping and a loud backfire.

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    R/A T/A SS/CETA's Avatar
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    My exhaust pops, but after owning a big block LeMans with Cherry Bombs I'm not easily shaken up by a little burping now and then.

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    Western Maryland LS1's
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    Mine pops - its kinda cool

    Borla catbacks and all the free intake mods with no tune.

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    Member jamessr's Avatar
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    I have a Borla and mine does it as well. Does it alot more when its cold tho.
    TBH tune it up and if its still there I wouldn't worry abou it.


    P.S. I slept at a Holiday Inn last night so I know what the fuck I'm talking about

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    I have a need for speed! jigger1166's Avatar
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    Quote Originally Posted by onetroubledguy View Post
    Thanks guys. Sorry for not being more detailed.

    I know that I have dual exhaust with cutouts but anything beyond that is unknown. I would also like to mention that this did not happen the first month and a half that I had the car (bought in August of this year). It has about 81k on it.
    Do you have headers? It could be caused by a leaking header gasket that wasn't leaking the first month and a half.

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    well depending on the exhaust i thought the dfco was the cause of popping....and if it just started and you have factory exhaust look for leaks..

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    Member 180ls1's Avatar
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    it could be the packing in your mufflers if you have those type like glasspacks or something that has packing in them

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    Veteran 0rion's Avatar
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    the popping is normal. What about the rough decel? Can you describe that any better? What do you mean you can "hear and feel it"?

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