PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

burst knock enable, for pinging?

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Old 10-02-2006 | 02:37 PM
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Default burst knock enable, for pinging?

In the table for burst knock enable load delta, what do the numbers mean exactly? Rate of change in MAP? I'm wondering why the numbers are bigger at lower rpm - wouldn't you want the burst knock prevention to kick in easier at lower rpm than at higher rpm?

I'm asking since just moved to AZ, where the gas is crappy (91 octane) and the temps are still in the upper 90s or more. Now getting definite tip-in pinging, trying to figure the best way to deal with it.
Old 10-02-2006 | 05:36 PM
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Delta Dynamic Cylinder Air. Grams/cyl, per 12.5mS
time-tick. If you are logging at 10/sec, divide the
frame-frame difference in CylAir by 8 to get it to
the same basis the PCM uses.

Drive around, make it ping and find the delta value
in this way that precedes ping bursts, and what is
sub-critical. Do it at varying RPM points with varying
throttle position and rate of roll-on until you have a
solid map of where you need to put the dividing line.
Old 10-02-2006 | 08:12 PM
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pcmforless disable mine is that bad?
Old 10-02-2006 | 09:23 PM
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Originally Posted by jimmyblue
Delta Dynamic Cylinder Air. Grams/cyl, per 12.5mS
time-tick. If you are logging at 10/sec, divide the
frame-frame difference in CylAir by 8 to get it to
the same basis the PCM uses.

Drive around, make it ping and find the delta value
in this way that precedes ping bursts, and what is
sub-critical. Do it at varying RPM points with varying
throttle position and rate of roll-on until you have a
solid map of where you need to put the dividing line.
OK got it, sort of. But still confused about whether I'll need to increase the delta value, or decrease it, to get rid of ping.

Also, should I be messing with this, or maybe with transient fueling instead?
Old 10-02-2006 | 09:39 PM
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Delta value is only the trigger threshold. You lower it to
bring in burst knock retard at less of an air-step.

You also want to figure out how much retard you need
to suppress ping reliably. This is in the retard vs RPM table.

The delta threshold in my stock tune is less than is normally
seen. So effectively it's not in play. Trucks however seem
to come with a much lower threshold (probably coupled to
the holding off of PE mode) and burst knock can really dog
them out.



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