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Old 12-12-2011, 12:29 AM   #1
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Default Definition of "Fuel Load"

My dad and I are currrently testing the MS3 with the Stim, but the lack of definition of some things makes it very slow going.

In spite of 20-30 min of googling and looking around, I have yet to find a good definition of fuel load. The only reference even close to useful was in the MSExtra FirstStart manual:

"Fuel load - show be close to 100kPa at sea level, down to say 80kPa at high elevations."

How does the percentage of the fuel load change? I see it in the fuel maps, but don't know where to aim at.
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Old 12-12-2011, 03:37 AM   #2
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Think of fuel load as your map sensor reading, cause thats what it is.

As to why its called fuel load... my best guess would be because 100kpa needs more 'fuel load' than 80kpa. therefore fuel load is used at part of the algorithm to determine how much fuel to dump into the motor.
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Old 12-12-2011, 10:44 AM   #3
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the fuel load %, as displayed on the fuel table, is equal the kPa reading.

100kPa = 100% fuel load = sea level atmospheric pressure.

general rule of thumb, if load/kPa increases, so does VE/fueling needs.
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Old 12-12-2011, 11:10 AM   #4
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Your fuel load is whatever mode you set under Basic Setup > Engine and Sequential Settings > Control Algorithm. This is the method used to determine engine load.

You can see that in the project I pulled up (randomly), the algorithm is set to MAFMAP. That means the MAP as calculated with a MAF sensor. Most applications use speed density, which uses MAP straight off a MAP sensor.

There are also other modes such as alphaN (for big cam or big/multithrottle N/A cars that don't make vacuum), MAF, and ITB (blends speed density with alphaN; a little more work to tune than alphaN but works awesome).

The Y axis "%" value will then vary with which algorithm you have chosen. With speed density, the values represent MAP. With alphaN, they represent throttle position, etc etc etc.

Note you can use the same control algorithm for both fuel and spark, or you can run different algorithms. For instance, you could run fuel off MAF and ignition off speed density if you wanted. Some would argue that it would provide for a more accurate tune. But I bet most would argue that it would just be more work.
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