Actual Timing > Spark Table

**JoshMcMadMac** · 09-10-2009

I was scanning on the way to work this morning, tweaking a few things. I noticed that the actual timing was typically several degrees higher than what I have in the spark table. What is influencing this? At "gentle" cruising the timing actually got as high as 50° where the table was only 45-47°. WOT I had readings at 16-17° when the table was only 12-13°. It seems like an extra ±5° is going into the whole thing, and I am wondering if anyone knows why, or where this is coming from.

Also, I recall most folks saying that 45° was the best/top/maximum that should be run (non-WOT) but I am curious where this number comes from as well.

**Damojo2003** · 09-10-2009

Well, the good spark table is only 1 table that is used in the calculation to determine the actual spark advance. I think the table that is adjusting the timing during your cruise is the EGR table. This adds timing when the egr is active. Keep in mind other tables are also affecting the timing like the air temp and coolant temp tables. Those are just 2 that come to mind. 50....I think that is the actual max timing allowed. I seem to think it was 48...I guess I am wrong. At WOT...I think the same tables are affecting your timing along with the spark afr table that everyone likes to zero out.

HTH

**JoshMcMadMac** · 09-10-2009

Originally Posted by Damojo2003

Well, the good spark table is only 1 table that is used in the calculation to determine the actual spark advance. I think the table that is adjusting the timing during your cruise is the EGR table. This adds timing when the egr is active. Keep in mind other tables are also affecting the timing like the air temp and coolant temp tables. Those are just 2 that come to mind. 50....I think that is the actual max timing allowed. I seem to think it was 48...I guess I am wrong. At WOT...I think the same tables are affecting your timing along with the spark afr table that everyone likes to zero out.

HTH

EGR is disabled. IAT was probably 60-80°F, and coolant was 180-190°F...I do not think I have and adder in those tables anywhere near those temps.

**BillBoost37** · 09-10-2009

There are a bunch of modifier tables. IAT and ECT are a couple.

**bilemke** · 10-02-2009

Most IAT and ECT spark tables are setup so that they will only have an effect at temperature extremes (well, not extremes, but above/below normal temps).

More common modifiers that are present, EGR and TCC spark.. TCC Spark taking timing away when tcc is applied. EGR spark adding timing when EGR is active.

**Reptile** · 10-06-2009

I know I'm way behind here, but there is a table not visible to the DHP tuner. Dave showed me in HPT that there is a table that typically adds 6 degrees to the cruise timing all through the tables. The exact name escapes me at the moment, but it states in the description that it adds overall timing in conjunction to the timing table, good spark or bad spark.

**bilemke** · 10-07-2009

That would be AFR spark.. It adds timing based on current commanded AFR. Note, at stoich AFR, the value is 0 (no additional timing).. Number/value increases as AFR decreases. Stock values vary a bit depending on year.

I think there are only like 7 AFR values/ranges.. The table is quite simple compared to the EGR and TCC spark tables.