PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

timing

Old Mar 23, 2005 | 12:18 PM
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I've set both my main and extended spark advance tables as well as setting my coolant correction is at 0. Why is my scanner showing me different timing values than the ones i set? What is changing them? Is there different variables i don't know about?

Last edited by Sotiri; Mar 23, 2005 at 01:29 PM.
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Old Mar 23, 2005 | 02:10 PM
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What system are you running?

Depending on the system you may have other things affecting the advance, like the IAT, knock retard, PE timing table, or maybe you didn't really zero out your ECT vs spark table like you thought. On older TPI systems the mask value is 20 instead of actually zero.

What exactly have you got and what is the difference you're seeing?
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Old Mar 23, 2005 | 02:22 PM
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I am running OBD1. Knock retard is off. Air temperature and PE affect timing? I haven't seen any tables on that!!!
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Old Mar 23, 2005 | 02:45 PM
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Originally Posted by Sotiri
I am running OBD1. Knock retard is off. Air temperature and PE affect timing? I haven't seen any tables on that!!!
Old TPI has another timing table for PE, and the LS1 has a table for the IAT, though it doesn't have much in it.

Are you talking timing only at idle, or everywhere? and how much is it off by?
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Old Mar 23, 2005 | 03:25 PM
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about 5* everywhere
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Old Mar 23, 2005 | 03:31 PM
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What is your base timing constant set at?
and are your scans showing 5* more or less than the tables?
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Old Mar 23, 2005 | 03:44 PM
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They are showing 38* instead of 33*. What is base timing constant?
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Old Mar 23, 2005 | 05:23 PM
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older cars with a real distributor used it to tell the ECM where initial timing was physically set at.
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