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--- bcssetup [2010/08/02 09:04]
twdorris
+++ bcssetup [2010/08/02 09:20]
twdorris
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 Now that you know you have control over boost, you basically just tweak the base duty cycle numbers to get the boost you want.  This might take some time, particularly in the areas where boost is typically building.  It's not bad, it just takes a few passes to get it right.
 ===== Approach 2: Enable error correction =====
+Start by following the procedure in Approach 1 to get your base duty cycle around where you want it.
+==== Setting up the Boost Target table baseline ====
+=== Explanation ===
+This step is **very** important to get a good baseline for error correction.
+Once you have the base duty cycle table set up, you'll want to start with a good Boost Target table that mimics what the turbo actually does.  This is particularly important in off boost areas where the turbo just can't build full boost.  Setting a boost target too high in this area *will* result in over shoot after you enable error correction because the error correction logic will ramp up the duty cycle trying to achieve a boost target that the turbo just can't do.
+So once you get into an area where the turbo **can** build boost, you'll already have elevated duty cycle values and the boost pressure will over shoot before error correction has a chance to drop the duty cycles back down.  This can also result in oscillation as the error correction logic tries to fix itself in both directions.
+So you can see it's very important to start with a Boost Target table that has an accurate representation of what the turbo can actually do.
+=== Collecting some data ===
+You do that by making a good, long 1st, 2nd and 3rd gear pull with error correction disabled and starting at an RPM below where the turbo can build boost.  So start at, say, 2500 RPM on a flat road in each gear and wind it out to, say, 7000 RPM at full throttle.  Repeat for each gear and maybe do a couple pulls like that.   You want as much data as you can.
+=== Use the Set Boost (WGS) tables helper function ===
+With that datalog displaced, right click on the graph and select the "Set Boost (WGS) tables" helper function.  This function averages the boost pressure and duty cycle at each RPM point and in each gear found in the current datalog and copies that data into the Boost (WGS) tab.
+When you do this with "good" data, you'll find a table similar to the following:
+{{  http://www.ecmtuning.com/wiki/_media/boosttarget.png  }}
+Note how each gear builds full boost at different areas of the RPM band.  And notice how this particular example shows some boost spike just as full boost is built.  You can either keep that spike in the curve or try to dial it out using lower duty cycle values and lower boost target values.  I personally like this spike, so I run it that way on purpose.  I want to get as  much as I can from my turbo.  So building more boost early on in the RPM band (where my turbo actually can build boost) is one way to do that.
 ===== Notes and limitations =====

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