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Old 06-07-2006, 09:17 PM   #33
silver arrow
Scooby Specialist
Member#: 25859
Join Date: Oct 2002
Chapter/Region: South East
Location: Foriderp
1965 MGB yellow
2008 Black Miata


Originally Posted by nhluhr
completely different topic. Knock correction is an instaneous thing that happens in response to detected knock and corrections linger for awhile until the ECU feels it can push it back again.

With AF Learned Trims, that is not something that can just be corrected immediately because it is so much more variable, thanks to effects from tip-in and lift-off. The ECU makes instantaneous corrections to AF in closed loop and then remembers a running average so to speak of those corrections for every single MAFv it has encountered and starts to modify the learned values.

The reason it's better to reset the ECU when this takes place is because resetting the ECU also takes the IAM back to the standard initial value of 0.5 (unless you or your tuner has changed it) which means you're not running full advance during this afr-uncertain time.

Also, experience has shown that Learned corrections which are made in closed loop DO get applied to open loop as well, but the mechanism by which that happens is not clear to me yet. A lot depends on the MAF sensor and the stored corrections so again... why chance it when you can just play it safe?
I still think you are way over estimating the change made by cleaning the MAF as far as worrying about the car's AF ratio. I would like to see one of the tuners from the board weigh in on this. Again the car will protect itself instantly with knock correction and will make the minor adjustments needed.
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