Rough idle wont stay running

1994 CHEVROLET SUBURBAN
203,000 MILES • 5.7L • V8 • 2WD • AUTOMATIC
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DOM78
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Check engine light on but only because the advanced timing wire not plugged in because when it is plugged in it idles rough, runs rich, and dies on me. When unplugged it runs great and there are no codes to be read. I had the whole top of engine rebuilt and timing chain done and gears and harmonic balancer all new and still no hope. Could it be my computer?
Aug 10, 2016 at 4:17 AM
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STRAILER
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That is a good one, can you check the base timing with the tan wire with the black stripe is unplugged? If okay then I would check all system grounds to make sure they are hooked up. It could be the ignition module or main coil that is shorting out for some reason when the wire is connected.

Here is a wiring diagram to make sure the ground are attached to the engine.

Please let me know what you find

Best, Ken

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Aug 11, 2016 at 7:54 PM
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DOM78
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The control module is new and coil new but yeah that's the wire I'm talking about the tan wire with black stripe when it's plugged in it runs like crap but when it's unplugged it runs great but the check engine light goes on because not plugged in. Can it be my ecu/computer?
Aug 12, 2016 at 3:32 AM
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STRAILER
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Yes it can be, here is one you can buy from amazon

https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=1994+CHEVROLET+SUBURBAN+ecm&rh=i%3Aaps%2Ck%3A1994+CHEVROLET+SUBURBAN+ecm

Please let me know how it goes

Best, Ken
Aug 12, 2016 at 11:05 AM