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LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Started new engine. Runs for only 3 seconds.....

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Old Feb 26, 2011 | 05:43 PM
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Default Started new engine. Runs for only 3 seconds.....
Well my new engine is finally done. But when I go to start it, it will only run for 3 to 4 seconds than die. Is there anything I could have disconnected that is causing it to die after a few seconds?

Also I have converted over to OBD1 and changed the knock sensor. Was I suppose to do anything else? Would it hurt if I put my OBD2 PCM back in just to see if it will stay running? The OBD2 PCM has a tune for a completely different cam, but I figured if I didn't WOT I would not hurt the engine. Correct?

I won't be leaving the OBD2 PCM in, just trying to see if the OBD1 PCM is bad.
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Old Feb 26, 2011 | 06:17 PM
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does the OBD1 PCM have VATS disabled?
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Old Feb 26, 2011 | 06:38 PM
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That ^

And I've seen this happen if your I injector size is WAY off
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Old Feb 26, 2011 | 06:40 PM
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Originally Posted by wysemunky
does the OBD1 PCM have VATS disabled?
Not sure. I'll have to ask the tuner. I did a mail order for now. If the VATS is not disabled, will the car start up for a few seconds then die like mine is?
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Old Feb 26, 2011 | 06:47 PM
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Possibly. Do you have your own cable or did you send in your pcm
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Old Feb 26, 2011 | 07:08 PM
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Originally Posted by gregrob
Possibly. Do you have your own cable or did you send in your pcm
I sent it to Moe Bailey. I'll get in touch with him. I can try and see if somebody has a cable here locally.
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Old Feb 26, 2011 | 09:07 PM
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Well switched to my OBD2 computer and it now does not die. Is there a way to disable or bypass VATS without sending off the computer?
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Old Feb 26, 2011 | 09:21 PM
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If you have your own cable....
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Old Feb 26, 2011 | 09:45 PM
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Originally Posted by gregrob
If you have your own cable....
I thought I read something about a bypass module you could use. Maybe that was something else. I'll just send the computer off again.
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Old Feb 26, 2011 | 09:47 PM
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There is 2 parts of VATS there is the chip inside the car that won't let the car turn over at all. Then the one in the computer which cuts off fuel
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Old Feb 26, 2011 | 10:19 PM
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just out of curiosity did you have to change out the coil... I was told you had to use the coil that goes with the pcm.
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Old Feb 27, 2011 | 01:25 AM
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Originally Posted by BigD383lt1
just out of curiosity did you have to change out the coil... I was told you had to use the coil that goes with the pcm.
if your referring to the ignition coil, thats not true as i am running an msd coil in my car
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Old Feb 27, 2011 | 07:52 AM
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there are two different year(style) coils one for the obd1 pcm and one for the obd2 pcm that does not have anything to do with the brand of the coil. I did a motor swap and put a 96 motor in a 94 car I was told to use the coil for the pcm not for the motor! I am not saying this the problem but would be very simply fix if it was.
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Old Feb 27, 2011 | 08:46 AM
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Originally Posted by BigD383lt1
there are two different year(style) coils one for the obd1 pcm and one for the obd2 pcm that does not have anything to do with the brand of the coil. I did a motor swap and put a 96 motor in a 94 car I was told to use the coil for the pcm not for the motor! I am not saying this the problem but would be very simply fix if it was.
But if I had the wrong coil it shouldn't run at all. Correct?
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Old Feb 27, 2011 | 08:56 AM
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not sure but if it running with the other pcm and not this one it is something to look at. I really don't know if it will cause the car to do this I just know that I was told to run the coil for the type of pcm not for the year of the motor.
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Old Feb 27, 2011 | 09:02 AM
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Originally Posted by BigD383lt1
not sure but if it running with the other pcm and not this one it is something to look at. I really don't know if it will cause the car to do this I just know that I was told to run the coil for the type of pcm not for the year of the motor.
If my tuner emails me back saying the VATS is disabled. I will definantly give the coil a try. Thanks.
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Old Feb 27, 2011 | 12:54 PM
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Make sure your Mass Air Flow is hooked up. It needs to read the air comming in to the engine...if mine is unplugged or not hooked up (connected to throttle body) then mine will start then die after a few seconds
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Old Feb 27, 2011 | 08:47 PM
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Originally Posted by katz_2003
Make sure your Mass Air Flow is hooked up. It needs to read the air comming in to the engine...if mine is unplugged or not hooked up (connected to throttle body) then mine will start then die after a few seconds
yes but he says it runs with his stock pcm...
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