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Popping back throught the intake

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Old 12-01-2007, 09:38 PM
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Car: 1988 Trans Am GTA
Engine: 350 TPI
Transmission: 700R4
Axle/Gears: 4.10's
Popping back throught the intake

Ok I just picked up my 88 GTA and I've noticed if I ease into the throttle it pops back through the intake manifold but if I give it full throttle it doesnt to it any help would be great. Thanks in advance

steven
Old 12-02-2007, 06:59 AM
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Re: Popping back throught the intake

i'd try a simple tune up,, plugs & wires first
Old 12-02-2007, 01:08 PM
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Re: Popping back throught the intake

I had a V6 in a truck one time that did that. A lobe on the cam was wore out causing the exhaust gas to go back out the intake. Might be it.
Old 12-02-2007, 07:20 PM
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Re: Popping back throught the intake

Also check the timing.
Old 12-02-2007, 07:30 PM
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Car: 1988 Trans Am GTA
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Re: Popping back throught the intake

Thanks everyone I just put new plugs in it and everyone else ive talked to has told me it might be timing as well so I'll check the timing when I get a chance to work on it again I hope its not the cam since it was just put in before I got the car
Old 12-02-2007, 08:22 PM
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Re: Popping back throught the intake

While your under the hood, double check all your vacuum lines just in case
Old 12-02-2007, 11:09 PM
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Car: 86 Camaro Z28/ 87 Camaro IROC Z28
Engine: 5.0L TPI LB9 / 5.0 TPI LB9 w/cam
Transmission: Built 700R4 with Transgo shift kit
Axle/Gears: 3.27 9 bolt Posi/ 2.73 10 bolt Posi
Re: Popping back throught the intake

Sounds like a lean backfire or your timing is way off. You said you just picked it up? ( if a mechanic touched it you need to find out what he did, especially if its a cross spark plug wire)
Old 12-03-2007, 11:27 AM
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Car: 88 GTA "Cocaine"
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Re: Popping back throught the intake

adjust the valves with it running
Old 12-03-2007, 12:12 PM
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Car: 1988 Z28 Camaro
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Re: Popping back throught the intake

Try to retard the timing a little.
Old 12-03-2007, 12:32 PM
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Car: 89' IROC-Z
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Re: Popping back throught the intake

My brothers car does this,

Everytime they (brother and buddy who is selling him the camaro) set the timing....run it for a little....it'll jump timing 180* and start backfiring out the carb....time it again run it again for a little then it jumps again.

What do you guys feel this might be? As he also has a cam installed and hasnt ran this motor in MANY MANY MANY years....maybe close to 10 years this motor hasnt been started. let me know.
Old 12-08-2007, 12:11 PM
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Car: 86 Camaro Z28/ 87 Camaro IROC Z28
Engine: 5.0L TPI LB9 / 5.0 TPI LB9 w/cam
Transmission: Built 700R4 with Transgo shift kit
Axle/Gears: 3.27 9 bolt Posi/ 2.73 10 bolt Posi
Re: Popping back throught the intake

From what i heard about motors that have been sitting for awhile, they dry out and the seals and gaskets dry out. The pistons and metal parts can actually seize if you try to run them and if it jumps the timing belt it may bend all the pushrods and mess up the lifters.

It sounds like there is something wrong mechanically with that engine. The cam and distributor have a gear that is supposed to run smoothly.

My dad and my friend wouldnt let me buy a truck with the owner having not run the engine after 2 years. THAT one has been sitting for 10. Expect to have to replace or rebuild that engine if he buys it.
Old 12-08-2007, 06:11 PM
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Car: 1987 Trans Am
Engine: 350 TPI
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Re: Popping back throught the intake

do a whole tune up, plugs, wires, cap, and rotor. sometimes worn out cap and rotor will cause backfire through intake. i had this happen on a tbi pickup truck. it was so bad it actually would flame out of the throttle body, but on a tbi the injectors are above the throttle blades.
Old 12-08-2007, 08:19 PM
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Re: Popping back throught the intake

Will indeed.
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