Backfiring after tune up
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Junior Member
Joined: Apr 2021
Posts: 14
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From: Rocky Mount, North Carolina
Car: 1989 trans am gta
Engine: 5.7 350 crate
Transmission: Automatic
Axle/Gears: N/A
Backfiring after tune up
So we did a slight tune up in my 1989 trans am gta. just put in new spark plugs, cap, and rotor. Started the car and noticed it started backfiring while idling. Checked oil and noticed just a couple tiny pieces of metal. Any idea what would cause this?
Joined: Nov 2008
Posts: 2,093
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From: Milwaukee
Car: 92 Firebird, 77 Trans Am SE, 86 Z28
Engine: 5.7 HSR, T/A 6.6, empty
Transmission: T-5, TH350, T-5
Axle/Gears: 3.08 posi, 3.23 posi, 3.23
Re: Backfiring after tune up
Recheck wires, you probably have some mixed up.
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Joined: Sep 1999
Posts: 3,003
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From: Colorado USA
Car: '83 Firebird (T/A Clone)
Engine: 350 with L-69 components
Transmission: 700R-4, 2000 RPM stall converter
Axle/Gears: 10-bolt/3.73 ..
Re: Backfiring after tune up
You have something else going on. Simply changing cap, rotor, & sparkplugs would not cause metal fragments in the oil. Improper ignition timing can cause a backfire...
Thread Starter
Junior Member
Joined: Apr 2021
Posts: 14
Likes: 0
From: Rocky Mount, North Carolina
Car: 1989 trans am gta
Engine: 5.7 350 crate
Transmission: Automatic
Axle/Gears: N/A
Re: Backfiring after tune up
It's also a newer motor so I don't know if that would have anything to do with a little bit of metal fragments.
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Joined: Apr 2021
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Re: Backfiring after tune up
Found ya Ken!
@aliceempire you where correct. We had a wire or two swapped. We pulled them all, found TDC on 1 and re-installed. Flushed the fuel tank, added new fuel and its running far better.
We also opened the oil filter up. There where some very small shavings in there, nothing substantial. Not knowing much at all about the motor, how long it was sitting, if it was started a bunch after sitting for a long time without priming etc we are not too concerned. We are going to move forward with it and see what it looks like after putting some miles on it.
@aliceempire you where correct. We had a wire or two swapped. We pulled them all, found TDC on 1 and re-installed. Flushed the fuel tank, added new fuel and its running far better.
We also opened the oil filter up. There where some very small shavings in there, nothing substantial. Not knowing much at all about the motor, how long it was sitting, if it was started a bunch after sitting for a long time without priming etc we are not too concerned. We are going to move forward with it and see what it looks like after putting some miles on it.
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