Quote:
Originally posted by Multiades
There are other explainations for it, but the theory IS correct because it MUST be. The only way to change A/F ratio without adjusting the ECU itself (directly) is to adjust the airflow value.
No matter what, for a certain actual amount of air massflow, a certain size injector, and a particular A/F ratio, the ECU MUST see a particular number. Any variation in those factors requires a variation in the airflow signal, and conversely, any change in airflow signal REQUIRES a change in one of those variables.
The only possible explaination for the changes you have observed, is that you are flowing more air (mass) at the same boost. Because you are flowing more airmass at the same boost, a higher frequency signal is required to inject the appropriate amount of fuel to mainain a particular airflow. The ECU runs less timing with a higher airflow signal (based on its internal maps).
The change from a peak of 2800Hz with honeycombs, to a peak of 2400Hz without is to be expected and NORMAL. You are only reading that signal as it comes from the MAS -- before it is "massaged" by the AFC.
Note that this change essentially proves my point because a lower frequency MAS signal for the same airflow essentially tells us that some of the correction is made at the MAS (and the remainder at the AFC).
If it doesn't make sense, there is always a reason. There isn't any magic in this business. Not that you could be blamed for thinking that this would result in less correction and less timing for those reasons -- I thought the same thing until what I just explained occurred to me.
Hope this helps,
-Chris
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There is no doubt that the timing is lower now than before. The car is blisteringly faster as well. Combo of more air and less timing works!
Somehow your theory doesn't apply to this situation, logical or not. Even if it HAS to be true as logic would dictate , the car is running less timing 6-8 degrees retarded) and is MUCH faster.