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Old 10-02-2013, 08:53 AM   #8 (permalink)
Sam Powell
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Join Date: Sep 2013
Location: Maryland, USA
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Fueling andtiming are extremely flexible with MEgasquirt. There are 3 primary, basic tables, and many trim tables. The basic ones are a 12x12 AF ratio matrix, a 12x12 fuel amount (called a VE table) and a 16x16 timing table. In each the rpm which is user defined is across the bottom of the table, and the MAP (load) goes up the vertical axis of the table. Every cell can have its own number. This means for every RPM and load you can have a specific timing and fueling amount. The wideband O2 sensor adjusts the fueling within the parameters the user sets to match what is in the AF table. The actual amount of timing or fueling is an interpolation of the number in the cell, and the numbers in cells around it if the RPM or MAP load is on the edge of two cells, or even 4 if it is in a corner.

I can make this engine run any way I want to. I just need to know what to try. I am not an IT person. Getting the soft ware downloaded and talking to the ECU was not easy, as I needed my daughter's help. So discussions of trying to get mileage feedback recorded and readable go over my head. This does not mean I am not interested in doing it some day. I can tune the actual ECU now, which was an accomplishment for a 68 year old man.

Right now the engine idles at 13.5:1 which is a little rich, but this is batch fire, multipoint injection, not sequential. There is fuel behind the valve awaiting its opening, which can get sucked into another cylinder and disrupt the AF ratio for that cylindar. However it runs at speed nicely at 16.5:1 as long as the load is low. It will cruise down a level highway at 45 MPH and 18 inches of vacuum all day. If I ever get the ECU reconfigured to read the pick up wheel and sensor instead of the distributor, I can set it up as sequential. But it runs now, and am not eager to shake things up much at this point.

The trim tables are such things as warm up enrichment, start up enrichment, start up timing, cold timing, etc. etc. There is an idle timing trim table that will bump extra timing into it when you first crack the throttle for drivability.

Thanks in advance for any tuning suggestions you can offer.
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