Ghettodyne 2.3
0.5 BAR
Joined: Jan 2003
Posts: 57
Re:Ghettodyne 2.3
Ok, as long as you read it! 
First let's remember that we are dealing with a primitive 8 bit controller that only understands 0-255 decimal, or FF hex, or 1111 1111 binary. 8 bits...that's all we have to work with. This makes it difficult to have one single algebraic equation to calculate 1.08 milliseconds all the way to 20.60 milliseconds based on a single variable (the fuel map data point). It is kinda like the revlimit and idle math...the smaller the number gets, the larger the number of equations are needed based on the answer. Anyways, Honda created 5 separate equations. Each is recognized by a multipler value (0-4). The equations are:
0: (x + 224) / 208 = ms pulse
1: (x * 2 + 224) / 208 = ms pulse
2: (x * 4 + 224) / 208 = ms pulse
3: (x * 8 + 224) / 208 = ms pulse
4: (x * 16 + 224) / 208 = ms pulse
Where x is the data point the ECU is grabbing out of the fuel map. Remember that you cannot have a number over 255 for x and you will quickly realize why there is a need for 5 equations. To get the high resolution values this was the only way to do the math back when an 8 bit controller was all that was available...think about where computers were back in 88-91!
So...to scale the fuel there are these different equations for various thresholds for injector pulsewidths. The PM6 has certain multipliers for certain columns BUT the LS ECU and PM7, and ZC, etc, etc. have DIFFERENT multipliers for the same columns because they require more fuel where the D16 didn't.
Now tuning an LS or ZC engine with a PM6 you WANT the different multipliers for those columns where you require more fuel and with the base PM6 multipliers you simply cannot achieve those fuel vales. Plug in 255 for x in the "3" multiplier equation. You come up with a max value of 10.84 milliseconds but you need MORE fuel with an LS or ZC engine so what can you do? Nothing at all unless you change the multiplier and then scale down the rest of the column to match. GhD re-scales the whole fuel table everytime you change a multiplier for a point of reference to supply the correct amount of injector pulsewidth.
Basically they let you add more fuel in the higher columns that an engine such as an LS or ZC motor needs. This is also why a PM6 can fully control a B16 fuel/ignition wise...the VTEC switch is still in testing mode.
Hope that helps.
Mike
First let's remember that we are dealing with a primitive 8 bit controller that only understands 0-255 decimal, or FF hex, or 1111 1111 binary. 8 bits...that's all we have to work with. This makes it difficult to have one single algebraic equation to calculate 1.08 milliseconds all the way to 20.60 milliseconds based on a single variable (the fuel map data point). It is kinda like the revlimit and idle math...the smaller the number gets, the larger the number of equations are needed based on the answer. Anyways, Honda created 5 separate equations. Each is recognized by a multipler value (0-4). The equations are:
0: (x + 224) / 208 = ms pulse
1: (x * 2 + 224) / 208 = ms pulse
2: (x * 4 + 224) / 208 = ms pulse
3: (x * 8 + 224) / 208 = ms pulse
4: (x * 16 + 224) / 208 = ms pulse
Where x is the data point the ECU is grabbing out of the fuel map. Remember that you cannot have a number over 255 for x and you will quickly realize why there is a need for 5 equations. To get the high resolution values this was the only way to do the math back when an 8 bit controller was all that was available...think about where computers were back in 88-91!
So...to scale the fuel there are these different equations for various thresholds for injector pulsewidths. The PM6 has certain multipliers for certain columns BUT the LS ECU and PM7, and ZC, etc, etc. have DIFFERENT multipliers for the same columns because they require more fuel where the D16 didn't.
Now tuning an LS or ZC engine with a PM6 you WANT the different multipliers for those columns where you require more fuel and with the base PM6 multipliers you simply cannot achieve those fuel vales. Plug in 255 for x in the "3" multiplier equation. You come up with a max value of 10.84 milliseconds but you need MORE fuel with an LS or ZC engine so what can you do? Nothing at all unless you change the multiplier and then scale down the rest of the column to match. GhD re-scales the whole fuel table everytime you change a multiplier for a point of reference to supply the correct amount of injector pulsewidth.
Basically they let you add more fuel in the higher columns that an engine such as an LS or ZC motor needs. This is also why a PM6 can fully control a B16 fuel/ignition wise...the VTEC switch is still in testing mode.
Hope that helps.
Mike
3.0 BAR
Joined: Jul 2003
Posts: 6,447
Re:Ghettodyne 2.3
I understand WHY DOHC motors need the fuel multipliers but I am having a hard time understanding which fuel multiplier values I use for my specific setup. When I click to configure "Fuel Multipliers", the fields are already popluated with values from 0 - 4. Are these a "base" that needs to be properly tuned or are there / will there be specific values that I need to put in for a specific engine?
I assume each variation of honda engine will need different settings and need to be properly/safely tuned?
If I need to becareful and tune these values myself for my specific setup, and my thoughts are correct, just give a nod...
Am I the only one or were others wondering this too? Or did I just blatenly miss something?
I assume each variation of honda engine will need different settings and need to be properly/safely tuned?
If I need to becareful and tune these values myself for my specific setup, and my thoughts are correct, just give a nod...
Am I the only one or were others wondering this too? Or did I just blatenly miss something?
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