Spark Retard
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From: Tallahassee, FL
Spark Retard I need some help on the "spark retard" tab.
Can I "0" out the burst knock retard tables? What will happen if I do?
Burst Knock Retard vs. RPM
Burst Knock Retard vs. RPM
I'm not in complete understanding of these tables yet.
What about Maximum Knock Retard?
My total Knock Retard is set at 15? Could anyone explain this to me?
I have no KR, and I'm in the process of adding timing wherever I can squeeze it at.
Thanks,
Kyle
Can I "0" out the burst knock retard tables? What will happen if I do?
Burst Knock Retard vs. RPM
Burst Knock Retard vs. RPM
I'm not in complete understanding of these tables yet.
What about Maximum Knock Retard?
My total Knock Retard is set at 15? Could anyone explain this to me?
I have no KR, and I'm in the process of adding timing wherever I can squeeze it at.
Thanks,
Kyle
Burst knock forces a knock retard whenever the
"delta cylinder air" exceeds the threshold (in
another table). It is a predictive knock retard,
complementing the reactive knock retard from
the engine knock sensors ping detection - BKR
is ping prevention for tip-in knock. But on the
trucks it's overdone.
When I tuned on a 5.3 truck I found that the
burst knock was killing performance for a
couple of different reasons.
1) large spark retard value. Set this to as little
as needed to prevent pinging on sharp, large
throttle transitions.
2) low burst knock threshold. I have never found
the timebase for the "delta CylAir" calculation, but
saw on this truck that just the normal RPM-rise
cylinder air increase on acceleration was making
burst knock trigger and stay triggered (motorboating)
all the way through 1st gear. Rasie this threshold
until you do not see burst knock except on very
large, very fast throttle events. Just increasing it
by 2X was enough for the continuous pulling to
go away but a faster-accelerating truck might need
it scaled more.
"delta cylinder air" exceeds the threshold (in
another table). It is a predictive knock retard,
complementing the reactive knock retard from
the engine knock sensors ping detection - BKR
is ping prevention for tip-in knock. But on the
trucks it's overdone.
When I tuned on a 5.3 truck I found that the
burst knock was killing performance for a
couple of different reasons.
1) large spark retard value. Set this to as little
as needed to prevent pinging on sharp, large
throttle transitions.
2) low burst knock threshold. I have never found
the timebase for the "delta CylAir" calculation, but
saw on this truck that just the normal RPM-rise
cylinder air increase on acceleration was making
burst knock trigger and stay triggered (motorboating)
all the way through 1st gear. Rasie this threshold
until you do not see burst knock except on very
large, very fast throttle events. Just increasing it
by 2X was enough for the continuous pulling to
go away but a faster-accelerating truck might need
it scaled more.
Thread Starter
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From: Tallahassee, FL
Originally Posted by MNR-0
Mines zeroed out. My tuner did it. No problems.
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Man, what a deceiving title. I figured you haven't been able to tune your timing like I haven't. That would make us both "spark retards". Just kidding.
I wouldn't zero out the burst knock tables. I think that is the KR that can help when a critical knock is hear that a lot of timing needs to be pulled really fast. Maximum KR is just that, the most KR your PCM will command, no matter how much the KR is modified by ECT or other tables. That way you don't end up at like -50 or something (not that it could, just an example). If you are not showing KR, there is no reason to mess with it. You just need to start raising timing until you do see KR, and then back it off a little.
I wouldn't zero out the burst knock tables. I think that is the KR that can help when a critical knock is hear that a lot of timing needs to be pulled really fast. Maximum KR is just that, the most KR your PCM will command, no matter how much the KR is modified by ECT or other tables. That way you don't end up at like -50 or something (not that it could, just an example). If you are not showing KR, there is no reason to mess with it. You just need to start raising timing until you do see KR, and then back it off a little.
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when the airflow delta is exceeded and burst knock tables are uses, does it actually show as KR even though it isnt really sensing "knock" just predicting it?? Id think every WOT shift you'd exceed the airflow delta.
Thanks
dave
Thanks
dave
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Joined: Mar 2004
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From: Australia
Well if its gonna knock its gonna knock, know what I mean? The problem with predictive retard is its almost always never wanted and not needed.
The knock sensors will always be your safety net. You can rely on that. So I cant see a problem with zeroing out the Burst knock retard.
The knock sensors will always be your safety net. You can rely on that. So I cant see a problem with zeroing out the Burst knock retard.