Erratic Idle
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Joined: May 2006
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Car: 89 Trans Am
Engine: 305 V8 TPI
Transmission: 700R
Axle/Gears: 308 Eaton Posi
Erratic Idle- Need some help pretty badly
Hey guys,
I have an 89 Trans Am, and I'm having some trouble with it that I hope you can help me with. The car originally had a 305 in it, but the previous owner swapped it for a 350 with an oversized cam and Edlebrock intake manifold and throttle body system. He replaced some of the electrical engine components as well, such as the distributor and thermostat, and I replaced the old 305 PROM with a new 350 chip. When I start the car, it goes to 1000 RPM, comes back down to about 500, then fluctuates in between the two for a couple seconds before it stalls out. If I depress the gas pedal to a certain point and keep it there, it will stay at a steady ~900 RPM. However, when I let it go, it stalls out immediately. Also, when I keep it at 900 RPM for a couple of minutes, my catalytic converter starts to turn red hot (towards the back end where it meets the exhaust pipe) and smokes (not out of the pipes, but its just so hot that it smokes). I thought it was backed up, but when I place my hand at the end of the exhaust pipe (I have the muffler off so I'm dealing with the pipe directly from the cat) I'm feeling the exhaust flow. Would you be able to tell me what the problem might be? I really don't want to sell the car, as I am being pressured to do, but want to work through this problem! >: ) If you need any more info, please just tell me, for all help is greatly appreciated as I am in dire need of it. At this junction, I don't know what the problem is as I've tried everything I can think of. Thanks everyone!
Mike
I have an 89 Trans Am, and I'm having some trouble with it that I hope you can help me with. The car originally had a 305 in it, but the previous owner swapped it for a 350 with an oversized cam and Edlebrock intake manifold and throttle body system. He replaced some of the electrical engine components as well, such as the distributor and thermostat, and I replaced the old 305 PROM with a new 350 chip. When I start the car, it goes to 1000 RPM, comes back down to about 500, then fluctuates in between the two for a couple seconds before it stalls out. If I depress the gas pedal to a certain point and keep it there, it will stay at a steady ~900 RPM. However, when I let it go, it stalls out immediately. Also, when I keep it at 900 RPM for a couple of minutes, my catalytic converter starts to turn red hot (towards the back end where it meets the exhaust pipe) and smokes (not out of the pipes, but its just so hot that it smokes). I thought it was backed up, but when I place my hand at the end of the exhaust pipe (I have the muffler off so I'm dealing with the pipe directly from the cat) I'm feeling the exhaust flow. Would you be able to tell me what the problem might be? I really don't want to sell the car, as I am being pressured to do, but want to work through this problem! >: ) If you need any more info, please just tell me, for all help is greatly appreciated as I am in dire need of it. At this junction, I don't know what the problem is as I've tried everything I can think of. Thanks everyone!
Mike
Last edited by 12gauge; May 23, 2006 at 07:14 PM.
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Joined: Mar 2004
Posts: 76
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Car: '83 T/A
Engine: 355
Transmission: BW T5
Axle/Gears: BW 3.27
I'm no expert in fuel injection.. Infact, I have very little knowledge about the specifics them(carb guy). However, it could be possible that your engine is running way too rich, or perhaps a dead cyl.
Can you smell gas strongly when the engine is running, or after has been running?
If it was me I would do a basic compression test... The reason being is that if you have too much gas in a cyl. (too rich/dead cyl) then the gas can get blown out through the exhaust valve.. it then runs down you exhaust where it can puddle in your cat, after it reaches a certain temperature the gas will then start to explode, thus causeing the hot cat.
Thats just a place to start though... good luck
Can you smell gas strongly when the engine is running, or after has been running?
If it was me I would do a basic compression test... The reason being is that if you have too much gas in a cyl. (too rich/dead cyl) then the gas can get blown out through the exhaust valve.. it then runs down you exhaust where it can puddle in your cat, after it reaches a certain temperature the gas will then start to explode, thus causeing the hot cat.
Thats just a place to start though... good luck
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