Differences

This shows you the differences between two versions of the page.

--- bcsoverview [2010/07/30 14:56]
twdorris
+++ bcsoverview [2010/08/02 07:33]
twdorris
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@@ Line 21: / Line 23: @@
 If error correction has been __disabled__, then this value is the final value the ECU is going to use and your turbo will build whatever boost it just happens to build for the given wastegate duty cycle.  You can use this mode of operation during setup and dialin to find where you setup naturally needs to be to build the boost you're looking for.
-If error correction has been __enabled__, then the ECU references the Boost Target table to determine (for the same RPM and gear) what boost it should be trying to achieve at that moment.
+If error correction has been __enabled__, then the ECU references the Boost Target table to determine (for the same RPM and gear) what boost it should be trying to achieve at that moment.  It then adjusts the base duty cycle according (up or down).  It tracks this adjustment with a "trim" value, similar to the short term fuel trim.  The final duty cycle used by the ECU is basically:
+  Final DC % = (base DC %) + WGSTrim
+The WGSTrim value is a loggable variable.
@@ Line 32: / Line 41: @@
 {{  http://www.ecmtuning.com/wiki/_media/mappinassignments.png  }}
-The ECU will compare current boost reported on the specified pin using the specified MAP sensor scaling against the target boost and determine a boost "error".  How far off the current boost is from the target boost will determine how much error correction is applied to the current duty cycle (which may have been corrected already by some amount from a previous pass!).
+The ECU will compare current boost reported on the specified pin using the specified MAP sensor scaling against the target boost pulled from the Boost Target table to determine a boost "error".  How far off the current boost is from the target boost will determine how much error correction is applied to the current duty cycle (which may have been corrected already by some amount from a previous pass through this correction process).
-The table used to define how much error correction to apply is found in the Direct Access tab.  It's listed there as WGSErrorCorr.  It defines a correction amount (expressed as duty cycle percentage) to apply to the current duty cycle based on a boost pressure difference.
+==== WGSErrorCorr - Direct Access table ====
+The table used to define how much error correction to apply is found in the Direct Access tab.  It's listed there as WGSErrorCorr.  It defines a correction amount (expressed as duty cycle percentage) to apply to the current duty cycle based on a boost pressure difference.  A bigger difference (larger error) typically results in a more aggressive (larger) adjustment to the base duty cycle.  But too much adjustment can result in oscillation.
 If you get oscillation or you want faster response, you can decrease or increase (respectively) the corresponding entries in the WGSErrorCorr curve.
-===== Altitude correction =====
+==== Altitude correction ====
 The pressure sensors used by ECMLink are all absolute pressure sensors because absolute pressure is far more useful to the ECU than "boost".  But the user is more familiar with "boost", so ECMLink provides an altitude correction factor to roughly translate absolute pressure to boost.
+===== Options =====

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