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

spark advance at idle

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Old Jun 7, 2009 | 08:47 PM
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Default spark advance at idle

what should it be? im trying to figure out why my car cuts out above 5500 rpm. i think its advancing the timing too far. its idling with about 42 degrees. that seems a bit high to me.
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Old Jun 7, 2009 | 09:27 PM
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Thats high. Mine bounces around 26-28.
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Old Jun 7, 2009 | 10:18 PM
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Originally Posted by ElkySS
what should it be? im trying to figure out why my car cuts out above 5500 rpm. i think its advancing the timing too far. its idling with about 42 degrees. that seems a bit high to me.
Perhaps that is high, but that does not mean timing at any other time will be higher. It does not have to progress in a linear fashion. It can be anything the programming tells it to be. Perhaps dissecting the tune you have would be a good idea (assuming it is non-stock).
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Old Jun 7, 2009 | 10:49 PM
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i have mine at 35.
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Old Jun 7, 2009 | 10:52 PM
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Maybe it's the opti?
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Old Jun 8, 2009 | 12:04 AM
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Watch what happens when you go wot to redline with the spark advance.

Mine is pretty aggressive, 42deg at the lower rpms but tapers off after 4500 or so to high 30's, and I'm not getting any knock retard.

Too much spark advance would show itself through knock retard long before it would make your car "cut out" I would think. Look at knock retard and if it's excessive, then you might be on to something. Most likely though it has to do with the ignition, with the opti being #1 suspect.
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Old Jun 8, 2009 | 12:25 AM
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Check your plug wires; if they are routed too close together that will also cause a high RPM miss - ask me know I know!

Originally Posted by gregrob
Watch what happens when you go wot to redline with the spark advance.

Mine is pretty aggressive, 42deg at the lower rpms but tapers off after 4500 or so to high 30's, and I'm not getting any knock retard.

Too much spark advance would show itself through knock retard long before it would make your car "cut out" I would think. Look at knock retard and if it's excessive, then you might be on to something. Most likely though it has to do with the ignition, with the opti being #1 suspect.
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Old Jun 8, 2009 | 12:30 AM
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new gm opti, it has been tuned but it had a bad opti on it at the time he was tuning it. he just tried to get it as close as he could, basically guessing. its also running rich as hell which i believe would make it a little more knock resistant
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