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--- ethanolsupport [2014/03/12 08:49]
twdorris [Operation]
+++ ethanolsupport [2014/06/05 09:14]
twdorris [Calculating global fuel scale]
@@ Line 59: / Line 59: @@
-The power connection (labeled "Vcc") needs to run to a +12v source. You can find +12v either straight off the battery (of course) or there's a +12v wire on the MAF connector harness too. This will be a thick red wire on pin 3 of a 1G MAF connector or pin 4 of a 2G/EVO3 MAF connector.
+The power connection (labeled "Vcc") needs to run to a switched +12v source. You can find a convenient switched +12v source on the MAF connector harness. This will be a thick red wire on pin 3 of a 1G MAF connector or pin 4 of a 2G/EVO3 MAF connector.
 The signal wire (labeled "Out") needs to run to the ECU's MAF input. This is pin 2 (green with blue stripe) on a 1G MAF connector or pin 3 (blue with yellow stripe) on a 2G/EVO3 MAF connector.
 ===== Operation =====
@@ Line 123: / Line 122: @@
-==== Calculating a new global fuel scale ====
+==== Calculating global fuel scale ====
+One thing that was mentioned above in the "Fuel increase at E100" section but might not have been clear is that you need to specify your global fuel adjustment on the Fuel tab assuming a 0% ethanol content. So before you first enable ethanol sensor compensation, you're going to need to adjust your current global scale value according to the ethanol content of the fuel currently installed in your tank to make it correspond to a 0% content value.
+To do that, you'll manually kick the fuel pump on using the button on the Misc tab, let the fuel circulate for a few seconds and then view the FlexFuelAdj log value to see how much of an adjustment ECMLink is going to make to your global fuel scale once enabled. Then you're just going to "undo" that adjustment on the global fuel scale so that once the adjustment is enabled, you'll end up right back where you started. This ensures a consistent transition away from having no automatic ethanol adjustment. An example will surely clear this up.
-One thing that was mentioned above in the "Fuel increase at E100" section but might not have been clear is that you need to specify your global fuel adjustment on the Fuel tab assuming a 0% ethanol content.  So before you first enable ethanol sensor compensation, you're going to need to adjust your current global scale value according to the ethanol content of the fuel currently installed in your tank to make it correspond to a 0% content value.
+**Example:** Current global fuel = -40.5% before installing the ethanol sensor. Once installed and the fuel pump is run for a few seconds, FlexFuelAdj reads +35.9%.
-To do that, you'll manually kick the fuel pump on using the button on the Misc tab, let the fuel circulate for a few seconds and then view the FlexFuelAdj log value to see how much of an adjustment ECMLink is going to make to your global fuel scale once enabled.  Then you're just going to "undo" that adjustment on the global fuel scale so that once the adjustment is enabled, you'll end up right back where you started.  This ensures a consistent transition away from having no automatic ethanol adjustment.  An example or two will surely clear this up.
+**STEP 1: ** New global = (current global + 1) / (FlexFuelAdj + 1) - 1\\
+**STEP ****2: ** New global = (-0.405 + 1) / (0.359 + 1) - 1\\
+**STEP 3: ** New global = 0.595 / 1.359 - 1\\
+**STEP 4: ** New global = 0.438 - 1\\
+**STEP 5: ** New global = -0.562 or **-56.2%**
-\\
+So you would change the -40.5% global fuel to -56.2% before enabling the ethanol sensor adjustment in ECMLink.

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