18572A 1 Mercury FORWARD GEAR

Table 1
Recommended Inlet Manifold Pressure    
Engine RPM     Inlet Manifold Pressure (1)    
900    
40 5 kPaa (5.8 .7 psia)    
1000    
50 5 kPaa (7.3 .7 psia)    
( 1 ) kPaa is kilopascal measured in absolute pressure.These recommended values are provided for reference only. Parasitic loads affect the required inlet manifold pressure. The engine choke trim can and should be adjusted to a manifold pressure level that provides the optimum engine stability and the load acceptance capability for the specific application of the engine.Use the following guidelines for the proper adjustment of the choke trim.
The choke trim should be adjusted in order to get an average exhaust port temperature of 500 to 550°C (932 to 1022°F) when the engine is operating below 40 percent load.
If the wastegate is in the closed position, the engine may be over choked. The choke trim setting on the DDT needs to be made more negative in order to reduce the choking. This will permit the wastegate to help control the desired air fuel ratio.
If the exhaust port temperatures are all lower than 500°C (932°F), then the engine is operating too lean. This can result in a high rate of cylinder misfires. The choke trim on the DDT needs to be made more positive in order to increase the choking.
The maximum exhaust port temperature should not exceed 600°C (1112°F). If the exhaust port temperatures are higher than 600°C (1112°F), the engine is not getting enough air. This can result in detonation and/or component thermal degradation. The choke trim needs to be made more negative in order to reduce the amount of choking. If only one cylinder exhaust port temperature is exceeding 600°C (1112°F), then investigate for a mechanical problem with that cylinder.Electronic Choke Trim Procedure
Set the engine operating condition to the rated speed and no load (or minimum load possible).
Connect the DDT to the Engine Supervisory System (ESS). Display the DDT screen "number 33" by pressing the "SELECT MODE" key in order to display the "CSP MENU" (customer selectable parameters) screen "number 03". Then press the "SELECT FUNC" key to display screen "number 33". Or simply enter the "number 33" and then press the "ENTER" key.Screen "number 33" on the DDT will display the following:"CHOKE TRIM""00 40/0900 33<"The numbers on the second line of the display are: The choke trim "OFFSET" number which indicates the amount of offset that has been entered through the "ALT1" and the "ALT2" keys. The amount of the choke trim offset "00" represents the factory default setting. "40/0900" represents the Inlet Manifold Pressure (kPaa)/Engine speed (rpm).Note: kPaa is kilopascal measured in absolute pressure.
On the DDT screen "number 33", when the "ALT1" or "ALT2" keys are pressed, a command signal is sent to the choke actuator in order to change the position of the choke plate.To raise the inlet manifold pressure, press the "ALT2" key. (The offset number on the DDT screen will decrease by one every time the "ALT2" key is pressed.)To lower the inlet manifold pressure, press the "ALT1" key. (The offset number on the DDT screen will increase by one every time the "ALT1" key is pressed.)This process should