E38 idle spark limit?!

[TRStech]

Hi all,

sorry, I have a weird question. Im tuning for German emissions insanity and therefore I need horrible idle spark advance values in order to get the converters heated after cold start. I retarded catalyst heating spark massively, still hunting for the possible limit while driving ([ECM] 12676), but getting closer. Anyway, the time I have during the emissions test in idle is by far the most effective time to light up the converters. For sure I retarded the idle catalyst heating spark also ([ECM] 12679 & 12680) and this gave me good resuts. However, there seems to be some limit setting not allowing less then -7 BTDC (or if you want so 7 ATDC) spark advanced (PID "idle advance") when in idle.

Can somebody point me a direction where this limitation might come from? Is it maybe a value or table we dont have access to? I already tested to reduce the base min spark table ([ECM] 12701), but this seems to dont have any effect on this phenomenon.

I need the hell's fire in the headers while idling after cold start! It's kind of stupid, I know, but unfortunately I need to tune for...

Thanks in advance!

[kevin87turbot]

It's likely being limited by the Final Minimum Spark table. Once you adjust it accordingly, you should be able to bring hell's fire to your cats.

[TRStech]

Unfortunately not. As already said I tested to adjust min final spark base ([ECM] 12701). It showed -10 for the rpm vs. cyl air in question before the change. Actual idle spark was -7. A change of the table to -15 resulted still in a idle spark of -7, so I took this change back. Once I found the real reason for reducing spark not below -7 I might again need to change this table ([ECM] 12701), but for now this one is not the reason for the limitation.