I converted to 730 ECM and am new to the speed density world. I couldn't readily find the answer to my question.

For the $8D mask is base timing included in the main spark table? I seem to recall that it isn't and that base timing must be added to the main spark table in addition to the PE timing.

Total Timing = BaseTiming + MainSparkTable + PETiming - KnockRetard

this is correct, right?

For the '165 $6E the timing was included in the main spark table.

thanks,
James

 

For the AUJP, yes. There is also "Highway Mode Spark Advance" that may need to be added.

 

Unless you have the older version of $6d it already has the base added.
But the latter version (version AB) does not add the pe or base.

 

hmmm. My data shows that in my tunercat version $8D 'AB' the base timing IS added in the main table already. My scanner report this as well. A friends bin file using an older definition file is exactly 6* lower than when I look at the same file with my definition file. That 6* is the same value of his stated base timing.

 

I cannot comment on $8D version AB. I've been using my own "modified version" of $8D for the past two years. The version I used ALWAYS treated the Main Spark Tables strictly as "relative" requiring you to add the base + PE + HMSA - Knock Retard.

I beleive TC may have added a 6* "offset" for display purposes. I will have to check out their "algorythm" with the TDF Editor later. Of course, that raises the question "What happens if your base is NOT 6*"?

 

Straight from TC,
Hi Tom,

This depends on what version of the $8D ECM Definition File you're using. Earlier version mistakenly included the initial spark advance value into the Main Spark Advance table. Since this value is the initial spark setting that is mechanically set by the distributor it is not a spark bias for the main table and should not be included in the table values. If you are using the current $8D Definition File (version AB) the initial spark advance value is not included and you would need to account for the initial spark advance when relating the main spark advance table values to actual measured spark advance.

Best Regards,

TC

 

The base spark was not included in the Main Spark Table in Version "P" of the $8D. I suspect the "error" occured in an earlier version and probably has been fixed since Version "P". I actually know that it was fixed since around "J".

After version "P", I've been using my own TDFs so I cannot comment if TC brought back the errant calc.

But for simplicity sake, for the AUJP bin the calc is:

Total EFFECTIVE Timing = Base + Main (or Extended if RPMs > 4,800) + PE + HMSA - Knock Retard. On a Scan Tool, the Total Spark Advance does NOT deduct the Knock Retard. The Total Spark Advance is REALLY the "desired" Total Spark Advance. It does not accound for the Knock Retard taken out.

If you reconcile your spark advance you will notice the following calc:

Total Spark Advance - Knock Retard = Relative Spark Advance + Base Timing. The Relative Timing = Main Spark Table (or Extened if RPM >4,800) + PE + HMSA - Knock Retard.

Just don't rely on the "total spark advance" displayed by the scan tool. It doesn't account for knock retard pulled.