BiDi control

[Chevy366]

Ok rookie question here , I was playing with the BiDi controls , mainly the two spark ones , Absolute and Delta .
I noticed that when I used the Delta to add spark I liked the results , so where does the Delta control add the values to ? What tables and how do I make it a permanent value .

[Blacky]

The Delta spark override adds the specified advance to the final spark advance, i.e. the SAE.SPARKADV PID.

The SAE.SPARKADV PID's value is derived from about 15 different tables. There is no single/simple place to add spark. You need to determine the conditions under which you want to add the spark, then modify the table that gives you control under those conditions.

i.e.
Add the delta spark to the high-octane spark table to adjust the spark under normal driving conditions (i.e. no knock, not cold/hot engine, not idle).
Or
Add the delta spark to the base spark table(s) to adjust the spark at idle.
Or
Add the delta spark to the coolant/intake temp spark table(s) to adjust the spark at only certain temperatures.

By logging the GM.EST_xxxx_DMA PIDs you can get an understanding of which tables are contributing how much advance (or retard) to the final spark advance.

Hint: Right click on the GM.EST_xxxx_DMA PIDs in the [PIDS (F8)] tab page and select, "More info..." to see which tables each DMA PID exposes.

Regards
Paul

[Chevy366]

So I would assume then that the Absolute does much the same thing then or does it target a smaller set of tables ?

[joecar]

Absolute is the final spark value.

[Chevy366]

Advance till knock then retard , advance till knock then retard , no better way ?

[dc_justin]

Advance till knock then retard , advance till knock then retard , no better way ?

The only way to know what timing will work best is to find it on a dyno. By advancing til knock and then retarding, you have no way of knowing if that advance point is actually best torque or not...

[Chevy366]

The Delta spark override adds the specified advance to the final spark advance, i.e. the SAE.SPARKADV PID.

The SAE.SPARKADV PID's value is derived from about 15 different tables. There is no single/simple place to add spark. You need to determine the conditions under which you want to add the spark, then modify the table that gives you control under those conditions.

i.e.
Add the delta spark to the high-octane spark table to adjust the spark under normal driving conditions (i.e. no knock, not cold/hot engine, not idle).
Or
Add the delta spark to the base spark table(s) to adjust the spark at idle.
Or
Add the delta spark to the coolant/intake temp spark table(s) to adjust the spark at only certain temperatures.

By logging the GM.EST_xxxx_DMA PIDs you can get an understanding of which tables are contributing how much advance (or retard) to the final spark advance.

Hint: Right click on the GM.EST_xxxx_DMA PIDs in the [PIDS (F8)] tab page and select, "More info..." to see which tables each DMA PID exposes.

Regards
Paul

Thanks for the explanation .

[ringram]

Yeah my dyno investigations showed peak power to be in some cases miles from knock. Like 5*+ easy.

Rich

[Whippled 496]

I ran a better quarter with 13.5* than I did with 16*.......seems odd, but true.

[Chevy366]

What gets me is where is the modification from the spark coming from , example , in H.O.T (H.O.T. and L.O.T. are the same values)
when watching a logged file I see spark knock and the H.O.T. cell it is in shows that he timing is at 25* and the logged data says 31* , I looked at all the modifiers and did not see any influencing the final spark value , but it is there .

[dc_justin]

What gets me is where is the modification from the spark coming from , example , in H.O.T (H.O.T. and L.O.T. are the same values)
when watching a logged file I see spark knock and the H.O.T. cell it is in shows that he timing is at 25* and the logged data says 31* , I looked at all the modifiers and did not see any influencing the final spark value , but it is there .

What PID are you using for air mass reference?

[Chevy366]

Will check , but right off the top of my head I can't say.
IAT and ECT are at 0 zero values as well as Octane scaler and I can't remember the rest but I will run the log again and make a note .
I am in Linux right now so can't run log .

[dc_justin]

Will check , but right off the top of my head I can't say.
IAT and ECT are at 0 zero values as well as Octane scaler and I can't remember the rest but I will run the log again and make a note .
I am in Linux right now so can't run log .

My guess is that whatever PID you're using to reference is incorrect. Use GM.DYNCYLAIR, not DYNCYLAIR_DMA PID.

[Chevy366]

Pretty sure I have those two selected , but will make sure , but will be later on .
Would I not see any values if they were not selected PIDs , in other words they would have to be there or no readings correct .

[Chevy366]

My guess is that whatever PID you're using to reference is incorrect. Use GM.DYNCYLAIR, no DYNCYLAIR_DMA PID.
Please would you explain why those two PIDs for Spark Knock and or Spark Advance .

[dc_justin]

Please would you explain why those two PIDs for Spark Knock and or Spark Advance .

Not those two, the first one, GM.DYNCYLAIR for air mass reference.

Your spark tables have are laid out as spark advance per rpm and air mass. Without referencing the correct air mass PID, you won't know which spark table cell exactly the PCM is looking up.

[Chevy366]

Thanks , got side tracked today , I did look and I did not have the GM.DYNCYLAIR selected will do another log and see what is going on .

[Chevy366]

I re-ran the log , when I looked earlier the Scan Tool had defaulted to the Metric PIDs , I switch to the PIDs that I had used to log the data with and the GM.DYNCYLAIR IS SELECTED as a PID selection , it is a modified AutoVE PID I made , so what I was seen is correct .
So what could be modifying the Spark ? It seems on average 6*s .
I don't remember seeing it in the tunes before I switched to the COS3c .
I realize there are modifiers but like I said earlier from what I saw they were all zeroing no modification going on .

[dc_justin]

I re-ran the log , when I looked earlier the Scan Tool had defaulted to the Metric PIDs , I switch to the PIDs that I had used to log the data with and the GM.DYNCYLAIR IS SELECTED as a PID selection , it is a modified AutoVE PID I made , so what I was seen is correct .
So what could be modifying the Spark ? It seems on average 6*s .
I don't remember seeing it in the tunes before I switched to the COS3c .
I realize there are modifiers but like I said earlier from what I saw they were all zeroing no modification going on .

Would you mind posting up a copy of your log and tune?

Have you checked table B5908?

[Chevy366]

Would you mind posting up a copy of your log and tune?

Have you checked table B5908?

No don't mind , was going to ask if someone would take a look .
I may be seeing something that is not there or just looking at it wrong (most likely) .

Nope but will check , B5908 .

[Chevy366]

Here are the logs .

[dc_justin]

Okay, looking at your log there, you're not logging any PID for airmass. Without that, you really have no way of knowing what cell is being referenced in your spark table.

Also, I'm seeing 25* in your logs at WOT...

[Chevy366]

I looked at the PIDs for the log it shows the GM.DYNCYLAIR (has little gage highlighted) and has it selected in the PID as a traceable selection .
Frame 3520 to 3540 , I think in the second log , true or false KR .
Maybe I put the wrong logs up .

[Chevy366]

Those were the wrong logs , I have the flu and makes it hard to concentrate (I have to search the Winders drive and pull them off it ) , I did some more logs today but I have modified the SHOT and the SLOT and do not see the timing offsets as much .

Thanks for the help dc_justin .