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Discussion Starter · #1 ·
So I have a 79 Pontiac firebird with a 301 and I just went through about two weeks of it not running. So I found the issue was my pickup coil which a bought a new one and installed it. I also installed a new ignition module and coil because I thought they were the problems however they weren’t. So everything is running smooth and I have it timed at 12 degrees BTDC but I noticed when the car gets up to temp I now have a very slight misfire. I tried changing the timing but it’s still there. Currently the car is at 15 degrees BTDC. Any suggestions on why I have a misfire and what the cause may be?
 

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1975 Firebird Formula / 400ci 6.6L V8 / TH350
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So I have a 79 Pontiac firebird with a 301 and I just went through about two weeks of it not running. So I found the issue was my pickup coil which a bought a new one and installed it. I also installed a new ignition module and coil because I thought they were the problems however they weren’t. So everything is running smooth and I have it timed at 12 degrees BTDC but I noticed when the car gets up to temp I now have a very slight misfire. I tried changing the timing but it’s still there. Currently the car is at 15 degrees BTDC. Any suggestions on why I have a misfire and what the cause may be?
I am not saying that this is your issue but since it last ran have you done anything with the Carb? dirt or worn parts can sometime have something to do with it. that's just one thing you could look at. also check your spark plugs are clean. also but probably not likely could be bad mixture of gas. these are just easy things to check.
 

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1975 Firebird Formula / 400ci 6.6L V8 / TH350
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I put in a new fuel filter but I only get the misfire when the car goes up to temp, I will try cleaning my plugs and wires
KEEP US POSTED :) . also if you replaced the fuel filter just make sure that nothing go in the line, if the line is clogged it could be struggling a little to deliver the fuel to the engine. if that's the only part of the system you opened up since last starting it could be something with that, if the misfire was not occurring prior to the repairs, and or the new distributor parts you got could be bad or going bad as well. auto part start have that from time to time (not likely but a possibility) just some things to look at
 

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1976,Firebird,Formula, 350 Engine,350 Trans.
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Did you replace the distributor rotor? With a white rotor you can see a burnt black place IF it has burned through, not so much with a black rotor. Especially if it has totally died
If it was a plug wire it would keep running.
 

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First, when you say car died twice do you mean the engine stopped running or it stopped running and you lost all power to gauges, radio, etc.

Second, your misfire. Did you try pulling plug wires while it’s running to determine if there’s a specific cylinder that’s misfiring?
 

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Discussion Starter · #10 ·
First, when you say car died twice do you mean the engine stopped running or it stopped running and you lost all power to gauges, radio, etc.

Second, your misfire. Did you try pulling plug wires while it’s running to determine if there’s a specific cylinder that’s misfiring?
engine stopped running, still had radio and electricity running through the car. it doesn’t seem to misfire when idle just when accelerating when up to temp
 

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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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Make sure all the spark plug wire terminals (both end) are not corroded, loose, or damaged. Make sure the plug wire sockets in the distributor cap are not corroded. Make sure there are no cracked or burned areas in the plug wires. When you place the engine under load, the voltage required to fire the spark plugs increases, and the high voltage will find weak points in the wires and the spark will not reach the plugs. Even if parts are new, make sure they are installed correctly.

Also check the accelerator pump in the carb. If it’s not adding the fuel required to match the increased air flow as the throttle blades open, it will misfire.
 
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