mark chandler
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| posted on 31/8/08 at 09:18 AM |
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Megasquirt question on MAP & RPM values
Hello
Do the MAP and RPM values need to be linear or can I have broad settings where the map is rarely used ?
With my squirted bike engine the MAP values when driving all revolve between 60 and 100, the scale on the side is 10, 20, 30, 40, 50, 60, 70, 80, 90,
100
What I would prefer is something more like 0, 20, 40, 60, 65, 70, 75, 80, 90, 100 so I can better MAP the system where the car drives.
For RPM my blade engine stops at 12,000 RPM so my mappings match this, however reading the manual the system honours the last value so if I set the
end at 10,000 rpm I gain more mapping points in the middle. Does this sound correct?
Regards Mark
[Edited on 31/8/08 by mark chandler]
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martyn_16v
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| posted on 31/8/08 at 12:00 PM |
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It does use the last value when you fall off the table. This doesn't mean that the fueling sticks at a constant value though, just the VE part
of the fuel equation, so more fuel will go in as rpm/map/tps continue to go up.
I'd worry about having the engine redline off the side of the table 
[Edited on 31/8/08 by martyn_16v]
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mark chandler
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| posted on 31/8/08 at 09:25 PM |
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On the basis that you do not hold the car at full power at max revs for long if it overfuels I should be okay.
Logging data will show values outside the parameters so I can easily validate to ensure nothing will fail here.
I fed my log into excel and pivoted the data, this shows that most of my driving occurs with a MAP value of 67 - 73, except on idle and overrun. The
RPM values duing this are between 3100 - 6900 so I want to concentrate getting things correct where I drive the car.
The lowest map value is 23, but its only really starting to read values at 30 so I can start my VE table here, values are still valid up to 100 but at
a low level from 37 -66 so I only need to gather basic data in this range.
This graph shows things more clearly
Regards Mark
 
Rescued attachment Blade MAP.JPG
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