PCM? Or alternator? Need help
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Joined: Jul 2009
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PCM? Or alternator? Need help Alright guys this problem is killing me. I have a 99 trans am ls1 auto, no ws6 package. When I originally purchased the car, I ran 13.50's all day long at 102-104. Since then within the last year, I have begun to experience a sort of short problem with the electrical system in the car.
When I am stopped at a stop sign or stop light, instead of my voltmeter sitting at 14 like every one else's does, I surge down to about 8-9.5 volts, in turn dimming all my lights and making the engine sluggish out of the hole. What the car does now is accelerates fine once you get going. Once I get around 75-80 mph, the voltmeter starts the bounce back and forth losing power. Anything after 100mph the car lights all dim real low, voltmeter surges to around 9 and major loss of power. With this problem I ran 14.20's-14.50's around 90 mph. These cars are not that slow stock hence why I bought it. I woulda bought a mustang if i wanted that.
No body can seem to figure out what the problem is. I tried two new alternator's. Both alternator's worked fine with no issues whatsoever for about a week maybe two at most, then went right back to the same problem. I'm at a loss. I want to yank my motor for mods but can't spend the money if I am going to permanantly have this problem of electrical issues. Has anyone experienced this or possibly know how I can fix it?
I appreciate any help you guys can give me Thank you
My email is transxtreme@yahoo.com if you need to email me.
When I am stopped at a stop sign or stop light, instead of my voltmeter sitting at 14 like every one else's does, I surge down to about 8-9.5 volts, in turn dimming all my lights and making the engine sluggish out of the hole. What the car does now is accelerates fine once you get going. Once I get around 75-80 mph, the voltmeter starts the bounce back and forth losing power. Anything after 100mph the car lights all dim real low, voltmeter surges to around 9 and major loss of power. With this problem I ran 14.20's-14.50's around 90 mph. These cars are not that slow stock hence why I bought it. I woulda bought a mustang if i wanted that.
No body can seem to figure out what the problem is. I tried two new alternator's. Both alternator's worked fine with no issues whatsoever for about a week maybe two at most, then went right back to the same problem. I'm at a loss. I want to yank my motor for mods but can't spend the money if I am going to permanantly have this problem of electrical issues. Has anyone experienced this or possibly know how I can fix it?
I appreciate any help you guys can give me Thank you
My email is transxtreme@yahoo.com if you need to email me.
Thread Starter
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Joined: Jul 2009
Posts: 5
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Both, at idle voltmeter drops low into the yellow zone dimming all my lights. If I accelerate like a human being, volts go back to 13.5ish and stay there until I slow back down to an idle. If I come out of the hole full throttle, you can see the lights dimming back and forth as well as the voltmeter. The faster I go and higher the RPM's, the volts just drop making the car sluggish, extremely. Dropped me from 13.5 to a 14.3 1/4 mile.
I took another member's advice who had the same problem. He replaced the plug into the alternator. Its a single wire plug that goes straight to the PCM. Fixed that and went for a spin. Hit 140 barely because the car was hesitating. Maybe the tensioner is bad, but is there a way I can check that or just replace it. How much did it cost?
I took another member's advice who had the same problem. He replaced the plug into the alternator. Its a single wire plug that goes straight to the PCM. Fixed that and went for a spin. Hit 140 barely because the car was hesitating. Maybe the tensioner is bad, but is there a way I can check that or just replace it. How much did it cost?
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make sure you check the grounds on the back of the heads they play a big role in everything on f-cars...check the power wire to the alt and check to make sure that the connector from the main power is conected good
