popping and flames out the exhaust
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iTrader: (3)
Joined: Nov 2001
Posts: 2,428
Likes: 2
From: Fairview Heights Illinois
Car: 1986 Irocz
Engine: 305 TPI
Transmission: 700R4
Axle/Gears: 3.25:1
Re: popping and flames out the exhaust
Hard to say without a lot more information about the conditions.
It's usually caused by an exhaust leak, and often combined with a rich condition on decel. That's if it only happens during decel.
If it happens other times then it could be a valve timing problem, or a cracked or bent valve.
Thread Starter
Member

Joined: Apr 2007
Posts: 389
Likes: 0
Car: 1987 iroc z
Engine: 350tpi
Transmission: 700r4
Axle/Gears: 342
Re: popping and flames out the exhaust
yes only on deceleration once it goes below 3100rpms till about 2000rpms. im definitly running a little rich on an untuned pcm. i have 24lb injectors and 50psi at idle
Re: popping and flames out the exhaust
i know this is stupid!but if you still have a.i.r. system on car diverter valve is probably bad.all that extra fuel on decel air is supposed to divert from exhaust system to atmosphere.if you still have it pull the belt off and see if it still backfires.
Junior Member
Joined: Feb 2010
Posts: 60
Likes: 0
From: NWI
Car: 92RS
Engine: 305 TBI
Transmission: 700
Re: popping and flames out the exhaust
Strong smell of gas from the exhaust or read the spark plugs. if they have heavy carbon deposits on them and your not burning oil then your running rich. (black, usually flaky deposits) The smell of gas in the oil would be another indication. if the condition is only under decell the this may or may not apply.
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iTrader: (3)
Joined: Mar 2010
Posts: 271
Likes: 3
From: sturgeon bay wisconsin
Car: 91 firebird
Engine: 350
Transmission: 700r4
Axle/Gears: stock
Re: popping and flames out the exhaust
i am running a 77 350 carb motor in mine with edl 600 and perf intake it seems no matter how i adjust the carb when i shut it off it stinks of gas under the hood. i just ran new fuel lines filter etc and checked everything all the way to the tank , even had the tank out. i just adjusted the valve lash today and it was quite off. i do have the charcoal canister hooked up . i also have a strong smell of gas out the exhaust. are these carbs just stinky or what could be causing this. also i have no insulation in the trunk and when i m goin down the highway if i open one window it stinks of exhaust, if i have them both up or both down it doesnt. could this be from not havin that insulation in the trunk...mind you i do have full duel exhaust from the headers back. and no leaks any ideas
Joined: Mar 2000
Posts: 43,187
Likes: 43
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Re: popping and flames out the exhaust
sounds like too rich with an exhaust leak.also remote but what is your tps voltage?ecm may not recognize throttle is closed if too high and not go into fuel cut mode and base idle timing.
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