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By Caseman
#58139
Hey guys is there a way to have my 0.4v pull timing out as you get on the throttle a little hard? Say i have 28 deg. at 2500rpm can i set up a way to pull out 8 deg. and bring it back in as the initial load is over to stop knock? like a old vacuum advance dizzy would do
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By jonbill
#58140
vacuum advance on a distributor adds advance at low load.
with Speeduino you can set whatever advance you want at any combination of load and rpm you want in the spark table.
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By jonbill
#58141
so, for example, if your engine knocks at WOT and peak torque rpm (e. g. 4500 rpm) then remove some advance in that region of the table.
By Caseman
#58142
jonbill wrote: Tue Aug 16, 2022 8:29 am vacuum advance on a distributor adds advance at low load.
with Speeduino you can set whatever advance you want at any combination of load and rpm you want in the spark table.
Yup i sure does and thats what i am after i want to have a high amount of advance at cruise for economy then as i get into throttle i want it to pull timing out to stop knock from the high advance then put it back in after a given amount of time say a second or two
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By digmorepaka
#58146
Caseman wrote: Tue Aug 16, 2022 8:54 am
jonbill wrote: Tue Aug 16, 2022 8:29 am vacuum advance on a distributor adds advance at low load.
with Speeduino you can set whatever advance you want at any combination of load and rpm you want in the spark table.
Yup i sure does and thats what i am after i want to have a high amount of advance at cruise for economy then as i get into throttle i want it to pull timing out to stop knock from the high advance then put it back in after a given amount of time say a second or two
Not sure what you mean by this, if it knocks at that load level x rpm initially it will keep knocking regardless if you drop it for 2 seconds, a proper knock control strategy will keep pulling timing until it stops knocking then stay there until timeout or enter a long term trim. The spark table is tuned rpm x load, so you can have your 28 degrees at 65kpa 2500rpm and 8 degrees at 100kpa 2500rpm.
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By PSIG
#58152
If you follow what they are both saying, if the engine does not det at (random) 2500 rpm at 65kPa cruise, it will not det on accel there either, and in-fact accel at that same rpm would be higher kPa (or there would be no accel), where you would have less timing. Post your tune and a log of the issue.

There are potentially other factors that could cause det at a specific kPa such as idling hot then accel, so det occurs; but that's a direct factor of temperature (the source of all det) and could be solved by other means, such as CLT or IAT timing corrections. Other factors such as low tooth count (and resulting calculations) could affect the transient timing, and other stuff. Try to determine what factors are inducing the det, and typically that will include logs.
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By PSIG
#58181
BTW - I didn't look at your file. Are you running SD (MAP) or Alpha-N (TPS)? Just for reference if it helps someone: All the above assumes SD, but if you use AN it can throw more or less timing in than the engine needs, as the position on the table is relative to throttle, not actual load. When you can't get a good load source, AN is what's left to use, but it is a "desired" load rather than actual. You can imagine how this can be a problem at times.
By lsdlsd88
#58669
on GM platforms is normally called burst knock retard.
it's a pre-emptive measure, sudden large change in airflow may lead to knock when going through the same load cells in a slow pull wont knock at all.

i'd love to see this implemented
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