Holley COMMANDER 950 - Manual (Page 15)

15
2.2 Alpha-N
An Alpha-N system is similar to a speed density EFI system, except that for step 1, the ECU will look at engine speed and the
position of the Throttle Position Sensor, instead of the MAP Sensor, to determine the value from the base fuel map. The
following flowchart (Figure 2) illustrates this example.
100.8%
1000 RPM 40
47 ° F
ENGINE
SPEED
THROTTLE
POSITION
(TPS)
MANIFOLD AIR
TEMPERATURE
MODIFIER
(Air Temp Sensor)
ACCELERATION
ENRICHMENT
(change in TPS and
MAP Sensor)
COOLANT
TEMPERATURE
MODIFIER
(Water Temp Sensor)
100.0%
180
°
F
BASE FUEL MAP
VALUE
32
AMOUNT OF FUEL
INJECTED
(Pulse Width)
3.1 ms
0.82v
CLOSED LOOP
FEEDBACK TO
MAINTAIN 14.7:1
AIR/FUEL RATIO
(Oxygen Sensor)
CLOSED LOOP
OR
OPEN LOOP?
AMOUNT OF FUEL
INJECTED
(Pulse Width)
3.8 ms
Open Loop Closed Loop
100.0%
No Change
Sensor Data
Input
ECU Calculations
and Adjustments
Key:
Figure 2 Engine at Operating Temperature – Alpha-N ECU Strategy Flowchart