1994 formula firebird backfiring like a mofo
07-03-2012, 10:27 PM
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1994 formula firebird backfiring like a **** Hey guys, I posted on camarozone, but wanted other peoples feedback here. My 94 formula firebird was only firing on 7 cylinders when I bought it due to a bad wire. When I was running on 7 the motor ran fine other than missing due to no spark in cylinder 6. Immediatly after replacing the wire it started backfiring all the time. Sometimes it backfires up near the motor(through the intake maybe?) other times its out the exaust. Anyone have any possibilities on this?
The car has a powerdyne supercharger, msd ignition box, and long tube headers. When I had the ses code read it said 02 sensors were bad
The car has a powerdyne supercharger, msd ignition box, and long tube headers. When I had the ses code read it said 02 sensors were bad
07-04-2012, 08:04 AM
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good luck Hey guys, I posted on camarozone, but wanted other peoples feedback here. My 94 formula firebird was only firing on 7 cylinders when I bought it due to a bad wire. When I was running on 7 the motor ran fine other than missing due to no spark in cylinder 6. Immediatly after replacing the wire it started backfiring all the time. Sometimes it backfires up near the motor(through the intake maybe?) other times its out the exaust. Anyone have any possibilities on this?
The car has a powerdyne supercharger, msd ignition box, and long tube headers. When I had the ses code read it said 02 sensors were bad
The car has a powerdyne supercharger, msd ignition box, and long tube headers. When I had the ses code read it said 02 sensors were bad
Try rechecking wires ,fireing order, sounds like one is off.(simpliest solution)
http://shbox.com/1/opti.jpg
07-04-2012, 01:00 PM
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Originally Posted by cookietime
Quote
If it ran fine , its something you did.
Try rechecking wires ,fireing order, sounds like one is off.(simpliest solution)
http://shbox.com/1/opti.jpg
If it ran fine , its something you did.
Try rechecking wires ,fireing order, sounds like one is off.(simpliest solution)
http://shbox.com/1/opti.jpg
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07-04-2012, 01:01 PM
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Originally Posted by gjohnsonws6
Check for arcing in the dark
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07-04-2012, 01:35 PM
#6
Just need a dark garage and a running car...sounds safe during the day right?
But yea you would literally see the spark arching or jumping.
You may just want to get a whole new wire kit. Do you know for sure its the same cylinder causing the problem?
Is the MSD ignition box nessecary? Can you just take it off and hook everything back up like factory?
But yea you would literally see the spark arching or jumping.
You may just want to get a whole new wire kit. Do you know for sure its the same cylinder causing the problem?
Is the MSD ignition box nessecary? Can you just take it off and hook everything back up like factory?
07-04-2012, 01:44 PM
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Originally Posted by trilkb
Just need a dark garage and a running car...sounds safe during the day right?
But yea you would literally see the spark arching or jumping.
You may just want to get a whole new wire kit. Do you know for sure its the same cylinder causing the problem?
Is the MSD ignition box nessecary? Can you just take it off and hook everything back up like factory?
But yea you would literally see the spark arching or jumping.
You may just want to get a whole new wire kit. Do you know for sure its the same cylinder causing the problem?
Is the MSD ignition box nessecary? Can you just take it off and hook everything back up like factory?
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07-12-2012, 04:51 PM
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That a SC V8 car shouldn't ever be ran on 7cyl's,
Get a sprAy bottle of water tonight and mist the wires with it running and see if it's arcing on anything, sounds like u fucked up
Get a sprAy bottle of water tonight and mist the wires with it running and see if it's arcing on anything, sounds like u fucked up
07-12-2012, 06:38 PM
#10
I have a boosted car that broke a valve spring on the old heads... It ran better with the wire removed from the messed up cyl than it did trying to ignite the hole with the busted spring....
07-12-2012, 08:47 PM
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Originally Posted by popo8
I have a boosted car that broke a valve spring on the old heads... It ran better
with the wire removed from the messed up cyl than it did trying to ignite the hole with the busted spring....
with the wire removed from the messed up cyl than it did trying to ignite the hole with the busted spring....
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07-12-2012, 10:07 PM
#12
07-13-2012, 06:00 AM
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Originally Posted by popo8
Quote:
Originally Posted by jhobbins
did it backfire at all?
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Sorry, I forgot to say that. lol
YES it was bad, and if I tried to roll into the throttle it carried on like there was no 2moro...
Originally Posted by jhobbins
did it backfire at all?
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Sorry, I forgot to say that. lol
YES it was bad, and if I tried to roll into the throttle it carried on like there was no 2moro...
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07-13-2012, 08:30 AM
#14
Well before i evrn pulled tge heads off to find out, i bought an entire top end for the car.... Pulled the motor and began the swap.... It was at that time i was able to inspect the valve. Some how i got lucky and there was no damage to thd valve or the piston.... Maybe because of the dished boost pistons..... Eitger way, i could have just taken a chance and replaced the spring. if i were u... And u have no intentions of doing a new top end start with:
-pulling valve cover and inspecting EVERYTHING. Start the car and inspect it running if inspecting it while off does nothing.
Then, report back. DONT get ahead of yourslf... You may just need to do some rocker/valve adjustment.
-pulling valve cover and inspecting EVERYTHING. Start the car and inspect it running if inspecting it while off does nothing.
Then, report back. DONT get ahead of yourslf... You may just need to do some rocker/valve adjustment.
07-13-2012, 09:05 AM
#15
A backfire through the intake means that combustion is happening WHILE an intake valve is open. This is either a mis-routed plug wire a stuck open intake valve, or a blown head gasket. For the exhaust popping, it means the combustion is still happening while the exhaust valve is open OR there is excess fuel vapor being ignited by red-hot carbon inside of the exhaust system.
07-13-2012, 09:36 AM
#16
A backfire through the intake means that combustion is happening WHILE an intake valve is open. This is either a mis-routed plug wire a stuck open intake valve, or a blown head gasket. For the exhaust popping, it means the combustion is still happening while the exhaust valve is open OR there is excess fuel vapor being ignited by red-hot carbon inside of the exhaust system.
07-13-2012, 11:32 AM
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Originally Posted by joelster
A backfire through the intake means that combustion is happening WHILE an intake valve is open. This is either a mis-routed plug wire a stuck open intake valve, or a blown head gasket. For the exhaust popping, it means the combustion is still happening while the exhaust valve is open OR there is excess fuel vapor being ignited by red-hot carbon inside of the exhaust system.
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07-13-2012, 12:20 PM
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Does it only backfire under load, or all the time? I know after my car sat for several years, and I got it back up and running, it would backfire like crazy when you put any kind of load on the engine. Otherwise, it seemed to rev and run fine. My problem was related to the opti innards being in bad shape, rust etc. Before my car went into storage, the water pump had been leaking a bit onto the opti.
07-14-2012, 01:53 PM
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Does it only backfire under load, or all the time? I know after my car sat for several years, and I got it back up and running, it would backfire like crazy when you put any kind of load on the engine. Otherwise, it seemed to rev and run fine. My problem was related to the opti innards being in bad shape, rust etc. Before my car went into storage, the water pump had been leaking a bit onto the opti.
