Woodward GECO, Technical Manual, Page: 77 / 90

Manual 03554 GECO

Stoichiometric
Woodward 69
11. Ramp the engine load up to the 100% power. Record the current Mdot_fuel
value. Enter this value into the last point of the Valve-Learn table.
12. Enter evenly distributed Mdot_fuel values into the remaining points of the
Valve-Learn table between 50% and 100%.
13. Verify that the EGO sensor health values are greater than 50% and that the
EGO1 sensor signal is reading below 0.8 Vdc. If the voltage is greater than
0.8 V, adjust the carburetor toward lean to bring this voltage below 0.8.
Repeat this for EGO2 if it is present.
14. Set the control mode to Manual, on page 1. Enter a valve position command
value of 35%. This will cause the EGO measurement to increase.
15. Close the carburetor “power valve” (or air/fuel ratio adjustment) toward lean
to bring the EGO voltage to approximately 0.780 Vdc.
16. Using an exhaust emissions analyzer, verify that the current air/fuel ratio is
correct for best emissions. If necessary, adjust the carburetor to tune the
lowest emissions. Record the EGO1, EGO2, EGO3 sensor readings; Valve1
and Valve2 position commands; and the Mdot_fuel value.
17. Enter this EGO1 (and EGO2) value(s) into the EGO1 (and EGO2) Base
value(s) on page 3. Enter the EGO3 value into the EGO3 Base value on
page 4. Enter the Valve1 (and Valve2) positions in all Bank1 (and Bank2)
points of the Valve-Learn table.
18. Enter 0.00 V for EGO3 Offset into the Valve_Learn at 100% load.
19. Set the circuit board toggle switch to Closed Loop. Verify that the control
mode is CL+Adaptive. Allow the control to stabilize and verify that the control
remains at the best emissions condition.
20. If the EGO voltage has regular, large swings under steady engine conditions,
the closed loop gain (CL Gain) can be lowered. The CL Gain also affects
response time, so operation during load or speed changes will suffer if the
gain is too low.
21. After the control is stable, if the emissions is not as expected, adjust the
EGO3 Base value a few millivolts at a time to get the proper emissions
levels. Once stable, read the steady EGO1 and EGO2 Target values and
enter these values into the EGO1 and EGO2 Base values.
22. Adjust the engine load to approximately 90%. Allow the engine to stabilize.
Record the Mdot_fuel value and enter it into the Valve-Learn table at the
next-to-last position. Adjust the EGO3 Offset value to achieve best possible
emissions at this load. Enter the current valve positions into the Bank1 and
Bank2 values on the Valve-Learn table. Repeat this process over the
operating range of the engine. At each of these points, verify that engine
emissions or exhaust oxygen are at the expected values. If not, adjust the
EGO3 Offset values in the table to achieve the desired results. Remember
that the control interpolates between points on the table.