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LH 2.4 Fueling

This page lists known fueling adjustments for LH 2.4 ECUs.



Main Fuel Trim Map


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Data type: 8-bit integer
Range: 0-255
Structure: 16x16 table w/axis, RPM vs. Load

LH 2.4 calculates injector pulse width using the AMM and the injector constants. This table is used to 'trim' that initial calculation. A value of 128 means no correction; deviations decrease or increase fueling by approximately 0.2% per point.

Fuel Multiplier (Fueling Constant #1)

Data type: 8-bit integer
Range: 0-255
Structure: 1-byte constant
Reference Values:
  • B204FT, 950 chip: 128
  • B230FT, 984 chip: 128
  • B230*T, 954 chip: 150
  • B230, 933 chip: 131

This adjustment changes the amount of fuel delivered globally. The result from the fuel table lookup is multiplied by this. Useful for scaling for injectors. Applied after constant #2 (below).

Higher values also DECREASE the calculated load. So, a higher value will increase the amount of fuel delivered, but also move you to a lower load cell.

Rough injector scaling equation

a = old injector value in cc/min
b = new injector value in cc/min
c = old injector constant #1
x = new injector constant #1

x = (a/b) * c


EXAMPLE:
On a stock 937 BIN (turbo), constant #1 is 150. Stock "greentops" flow ON AVERAGE (there's two variants AFAIK) about 318 cc/min. If we want to scale for 500cc injectors:

x = (318/500) * 150

318/500 = 0.636, * 150 = 95.4

So our new Fueling constant #1 would be 95 (or 96, I usually err on the side of rich)


Fuel Trim (Fueling Constant #2)

Data type: 8-bit integer
Range: 0-255
Structure: 1-byte constant
Reference Values:
  • B204FT, 950 chip: 128
  • B230FT, 984 chip: 80
  • B230*T, 954 chip: 128
  • B230, 933 chip: 128

This value is subtracted from the fuel table lookup result BEFORE the fuel multiplier (above) is applied. Essentially, higher values decrease the amount of fuel delivered. This may be considered a 'base fuel' adjustment of sorts.

Fueling Constant #3

Data type: 16-bit integer
Range: 0-65535
Structure: 2-byte constant
Reference Values:
  • B204FT, 950 chip: 192
  • B230FT, 937 chip: 153
  • B230FT, 984 chip: 153
  • B230*T, 954 chip: 153
  • B230, 933 chip: 192

This value is a 16-bit constant. It does not affect fueling directly, it is a fail safe threshold. It does not need changing in order to adjust fueling. More to come about it..

Fueling Constant #4

Data type: 16-bit integer
Range: 0-65535
Structure: 2-byte constant
Reference Values:
  • B204FT, 950 chip:2717
  • B230FT, 954 chip: 2443
  • B230*T, 984 chip: 2443
  • B230, 933 chip: 3889

Note: This used to be two seperate constants (#4 and #5) before it was recognised that it was a single 16-bit value.

This seems to adjust base fueling in an indirect way. Low values (> 1000) may cause fueling to happen erratically.

This one is very important, it is used in the main fueling calculation.

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