New ECT based AVCS tables in later models

[Td_d]

A new set of ECT related tables for both intake and exhaust AVCS has been found on the recent 11/12 Sti models. I've found them in the USDM roms, fairly easy to find them in any other rom.


These tables basically reduce the primary tables by a ratio at lower ECt levels, and mirror the emmissions 'hump' that one finds in the lower load / rpm stock AVCS tables. These should be amended to improve idling and to improve warm up catalyst heating. To quote the defs:


Intake:


This map selects the degree of intake cam advance correction based on engine coolant temperature. The amount of correction is governed by the Intake Cam Advance Angle (ECT Related) Multiplier table. The final AVCS angle formula is: (Intake Cam Advance Angle Cruise (AVCS) * (1 - Map Ratio E42)) + (Intake Cam Advance Angle Non-Cruise (AVCS) * Map Ratio E42) + (Intake Cam Advance Angle (ECT Related) * Multiplier)</description>

Multiplier


This is the multiplier to the Intake Cam Advance Angle (ECT Related) lookup result according to engine coolant temperture. A value of zero negates the affects of the Intake Cam Advance Angle (ECT Related) table.


Exhaust


This map selects the degree of exhaust cam retard correction based on engine coolant temperature. The amount of correction is governed by the Exhaust Cam Retard Angle (ECT Related) Multiplier table. The final AVCS angle formula is: (Exhaust Cam Retard Angle Cruise (AVCS) * (1 - Map Ratio E42)) + (Exhaust Cam Retard Angle Non-Cruise (AVCS) * Map Ratio E42) + (Exhaust Cam Retard Angle (ECT Related) * Multiplier)


Multiplier


This is the multiplier to the IExhaust Cam Retard Angle (ECT Related) lookup result according to engine coolant temperture. A value of zero negates the affects of the Exhaust Cam Retard Angle (ECT Related) table.




Interestingly enough, these also exist in earlier Roms (such as mine, 08), but the intake is only 2x2 and the exhaust 6x7, and are switched off by default. Obviously a practice run.


I'm sure this is all emissions based...

 

[HolyCrapItsFast]

Very interesting find and worth the effort. Thank for the info TD! The only question I have is can we log map ratio yet? I want to log this but I'm not 100% certain why yet :lol:

I was never able to get my head around the relationship between cruise and non-cruise maps and I am considering doing some tuning based on those as apposed to just making them both the same. I think once I better understand that I will better understand the relationship between the tables mentioned above.

 

[Td_d]

Yeah - map ratio has definitely been found - on the 08's up it's extremely pervasive - used basically for all cruise / non-cruise transitions. And there is definitely merit in playing around with different iterations of the maps in cruise vs non-cruise - just very time consuming. Then again, isn't this all :lol:

 

[HolyCrapItsFast]

Yes... Just when I thought it was all over... there's more!

and it always seems to be you behind it all haha :lol: