3500 ENGINE CONTROL,ELECTRONIC UNIT INJECTION PART.3

SYSTEM POWER SUPPLIES

The 3500B EUI system has one external and five internal power supplies with various voltages as shown.



EXTERNAL POWER SUPPLIES

ECM power supply                                            24 Volts


INTERNAL POWER SUPPLIES

Speed/Timing Sensor power supply                  12.5 Volts Injector power supply                                  105 Volts Analog Sensor power supply             5 Volts
Digital Sensor power supply                             8 Volts Wastegate Control
Solenoid power supply                                      0 - 24 Volts

The power supplies are described in detail in the following section.

ECM Power Supply

The power supply to the ECM and the system is drawn from the 24-Volt machine battery. The principle components in this circuit are:

- Battery
- Key Start Switch
- Main Power Relay
- 15 Amp Breaker
- Ground Bolt
- ECM Connector (P1/JI)
- Machine Interface Connector (J3/P3)

If the supply voltage exceeds 32.5 Volts or is less than 9.0 Volts, a diagnostic code is logged. (See the Troubleshooting Guide for complete details on voltage event logging.)

NOTE: The Ground Bolt and the Machine Interface Connector are the only power supply components mounted on the engine.

ECM power supply circuit

This schematic shows the principle components for a typical 3500B ECM power supply circuit. Battery voltage is normally connected to the ECM. However, an input from the key start switch turns on the ECM. Battery voltage may be checked using the service tool status screen.

The machine wiring harness can be bypassed for troubleshooting purposes. These steps are described in the Troubleshooting Procedure.

Notice the P1/JI and P3/J3 connectors in the circuit (described on the next slide.)

J1/J2 40 pin connectors

A common but vital part of all the power supplies (and sensor circuits) described to this point is the 40 pin connector
This slide shows the two ECM 40 pin connectors, P1 and P2, looking from the wire side. The pins highlighted in the P1 connector are for the ECM power supply circuit

The system also includes the J3/P3, 40 pin Machine Interface Connector. This 40 pin connector transmits the power supply from the machine wiring to the engine wiring harnesses.

The Troubleshooting Guide identifies the relevant pins for each circuit in this manner. The J3/P3 connector is identified identically and is also a part of the system power supply.

Speed/Timing Sensor Power Supply

The Speed/Timing Sensor has a dedicated power supply. The ECM supplies 12.5 ± 1 Volts to the Speed/Timing Sensor
Connectors A and B send the common power supply to the sensor. The C wire transmits a separate signal to the ECM.

This power supply is not battery voltage, but is generated and regulated within 1.0 Volt by the ECM. This power supply and the Speed/Timing Sensor are vital parts of the EUI system. A failure of the sensor will result in an engine shutdown.

NOTICE
Connecting another system or accessory to the Speed/Timing Sensor
power supply will cause an engine malfunction or failure.

Injector Power Supplies

The injectors are supplied with power from the ECM at 105 Volts. For this reason, precautions must be observed when performing maintenance around the valve covers.

On the 3512B and 3516B, two of the internal power supplies are used for the injectors. If a failure occurs, only one bank of injectors could have failed. On the 3508B, only one of the internal power supplies is used. As previously mentioned, the same ECM is used on all three configurations.

If an open or a short occurs in the injector circuit, the ECM will disable that injector. The ECM will periodically try to actuate that injector to determine if the fault is still present and will disconnect or reconnect the injector as appropriate.

Analog Sensor Power Supply

The Analog Sensor Power Supply provides power to all the analog sensors (pressure and temperature).

The ECM supplies 5.0 ± 0.5 Volts DC (Analog Supply) through the J1/P1 connector to each sensor.
A power supply failure will cause all analog sensors to appear to fail. The power supply is protected against short circuits, which means that a short in a sensor or a wiring harness will not cause damage to the ECM.

Digital Sensor Power Supply

The ECM supplies power at 8 ± 0.5 Volts through the J1/P1 connector to the following circuits:

- Throttle Position Sensor

- Fan Speed Sensor (if installed)

- Exhaust Temperature Sensors

The power supply is protected against short circuits, which means that a short in a sensor will not cause damage to the ECM.

Wastegate Control Solenoid Power Supply

The ECM supplies a PWM signal of 0 to 1.04 amps through the J2/P2 connector to the Wastegate Control Solenoid Valve.

The solenoid valve and power supply can be tested on the engine using ET and the Wastegate Position Test. Using the test, the pressure can be adjusted manually with the ET service tool from minimum to maximum. Therefore, this function can be used to verify the operation of the ECM, the power supply and the control valve.

The service tool status screen "Wastegate Position" reading can be used to show the position with 0% indicating the closed position and minimum current used, and 100% indicating fully opened with the maximum current used. This measurement can be used in conjunction with the desired and actual boost pressures to check the system operation.

ELECTRONIC SENSORS AND SYSTEMS

This section of the presentation covers the electronic sensors and related circuits for 3500B EUI fuel systems used in machine applications.

Engine and machine wiring block diagrams

This block diagram shows all the electrical circuits on the engine and the machine (Off-highway Truck). The engine circuits will be described first, followed by the machine circuits.

On the diagram, the dashed lines divide the engine mounted circuits and the machine mounted circuits.

Speed/Timing Sensing Circuit

One Speed/Timing Sensor is installed and a serves four basic functions in the system:
- Engine speed detection

- Engine timing detection

- Cylinder and TDC identification

- Reverse rotation protection

The Speed/Timing Sensor is mounted on the rear housing and is self-adjusting during installation
This type of sensor does not have a typical fixed air gap. However, the sensor is not in direct contact with the timing wheel, but does run with zero clearance. A Speed/Timing Sensor failure will cause an engine shutdown.

The sensor may be functionally checked by cranking the engine and observing the service tool status screen for engine rpm.

A sensor failure will be indicated by the active fault screen on the service tool. An intermittent failure will be shown in the logged fault screen.

The sensor has a dedicated power supply. A power supply failure at the ECM will cause the sensor to fail.

The sensor head is extended prior to installation. The action of screwing in the sensor pushes the head back into the body after the head contacts the timing wheel.

During installation, it is essential to check that the sensor head is not aligned with a wide slot in the timing wheel. If this condition occurs, the head will be severed when the engine is started, and some disassembly may be necessary to remove the debris.

As mentioned earlier, timing calibration is normally performed after the following procedures:

1. ECM replacement

2. Speed/timing sensor replacement

3. Engine timing adjustment

4. Camshaft, crankshaft or gear train replacement

Analog Sensors and Circuits

The following analog sensors may be used in various applications:

- Coolant Temperature Sensor

- Aftercooler Temperature Sensor

- Oil Pressure Sensors (2)

- Atmospheric Pressure Sensor

- Turbocharger Inlet Pressure Sensors (1 or 2)

- Turbocharger Outlet (Boost) Sensor

- Crankcase Pressure Sensor

Coolant temperature sensor

The Coolant Temperature Sensor supplies the temperature signal for the following functions:

- Caterpillar Monitoring System or VIMS instrument display, warning lamps and alarm

- Demand Control Fan (if so equipped)

- ET coolant temperature display

- High coolant temperature event logged above 107°C (225°F)

- Engine Warning Derate when 107°C (225°F) is exceeded or low oil pressure occurs (if so equipped)

- Reference temperature for Cold Mode operation


NOTE: All analog sensors use the common analog power supply of
              5.1 ± 0.2 Volts.

Aftercooler temperature sensor

The Aftercooler Temperature Sensor is mounted at the rear of the block (Off-highway Truck) and measures coolant temperature in the aftercooler circuit.

The ECM uses the sensor signal as a reference for the fan control. When high aftercooler temperatures are reached, the cooling fan speed is increased. Very high aftercooler temperatures will cause a VIMS warning event to be logged.

NOTE: This sensor measures the ability of the aftercooler to cool the air sufficiently for combustion. As a general rule, for every 1 degree that the combustion air is reduced in temperature, the exhaust will be reduced by approximately 3 degrees. High inlet manifold temperatures can significantly shorten the life of exhaust system components (i.e. exhaust manifolds, valves, turbochargers and pistons). High temperatures will cause a loss of power also

Oil pressure sensors

Three pressure sensors are used for the measurement of oil pressure:

- Two Oil Pressure Sensors (filtered and unfiltered)

- Atmospheric Pressure Sensor

The filtered and unfiltered pressure sensors are used together to measure oil filter restriction.

The filtered oil pressure sensor is used to measure lubrication oil pressure for the operator on the dash panel and for the technician on ET. The atmospheric pressure sensor is used with this oil pressure sensor to calculate the gauge pressure reading.

LUBRICATION OIL PRESSURE CALCULATIONS

MEASUREMENT                            MEASURED BY                       RESULT
  Oil pressure                      [oil press (A) - atmospheric (A)]     =    Oil pressure (GP)
Oil filter restriction  [Unfiltered oil press - Filtered oil press]    =  Differential pressure (?P)

These measurements are used to determine oil pressure for the ET service tool and for the dash display to alert the operator that an abnormal condition exists. The sensor operating range is 0 to 1000 kPa (0 to 144 psi) (A).

Two lubrication oil pressure sensors are installed on this engine. One sensor measures pressure before the oil filter, and the other sensor measures pressure after the filter. These sensors are used together to calculate oil filter restriction (?P).

NOTE :

(A)           =absolute pressure
(GP) = gauge pressure
 (?P) = differential pressure

Oil pressure map

Engine oil pressure varies with engine speed. As long as oil pressure increases above the upper line after the engine has been started and is running at low idle, the ECM reads adequate oil pressure. No faults are indicated and no logged event is generated. A delay (de-bounce time) built into the system prevents false events from being logged after start-up or after a filter change.

If the engine oil pressure decreases below the lower line, the following occurs:

- An event is generated and logged in the permanent ECM memory.

- A Category 3 Warning (alert indicator, action lamp and alarm) is generated on the VIMS and Caterpillar Monitoring System.

- The engine is derated (if so equipped) to alert the operator.

The width of the pressure band between the two lines is sufficient to prevent multiple alarms and events or a flickering warning lamp. (This pressure separation is referred to as hysteresis.)

Atmospheric pressure sensor

All pressure measurements require the atmospheric pressure sensor to calculate gauge pressure. All pressure sensors in the system measure absolute pressure. The sensors are used individually in the case of atmospheric pressure (absolute pressure measurement). They are used in pairs to calculate gauge pressures (oil and boost) and filter restriction.

All the pressure sensor outputs are matched to the Atmospheric Pressure Sensor output during calibration. Calibration can be accomplished automatically using the ET service tool or by turning on the key start switch without starting the engine for five seconds. The Atmospheric Pressure Sensor performs four main functions:

1. Automatic Altitude Compensation (Maximum derate 24%)

2. Automatic Filter Compensation (Maximum derate 20%)

3. Part of the pressure calculation for gauge pressure readings

4. Reference sensor for pressure sensor calibration

A foam filter is installed below the sensor to prevent the entry of dirt.

Automatic altitude compensation

Atmospheric pressure measurement by the sensor provides an altitude reference for the purpose of Automatic Altitude Compensation.

The graph shown here describes how derating on a typical 3500B starts at 7500 ft. and continues linearly to a maximum of 17000 ft. Other engines may start between 4000 and 12000 ft. depending on the application.

The advantage of the EUI system is that the engine always operates at the correct derating setting at all altitudes. The system continually adjusts to the optimum setting regardless of altitude, so the engine will not exhibit a lack of power or have smoke problems during climbs or descents to different altitudes.

NOTE: The EUI system has an advantage over a mechanical fuel system which is derated in "altitude blocks" (i.e. 7500 ft., 10000 ft., 12500 ft.). EUI derating is continuous and automatic. Therefore, a machine operating in the lower half of the block is not penalized with low power. Conversely, a machine operating in the upper half of the block will not overfuel with the EUI system.

Turbo inlet pressure sensor

The Turbocharger Inlet Pressure Sensor is used with the Atmospheric Pressure Sensor to measure air filter restriction. This function is known as Automatic Air Filter Compensation.

These two sensors are used to enable the Automatic Air Filter Compensation function by measuring the differential pressure across the filter.

The Turbocharger Inlet Pressure Sensor is also used as a back-up to the Atmospheric Pressure Sensor for Automatic Altitude Compensation.

Depending on the inlet and air filter configuration, some applications may have two inlet pressure sensors (i.e. separate left and right systems with no connecting balance pipe)

Automatic filter compensation

Automatic Filter Compensation means that the engine is protected against the effects of plugged filters. Derating is automatic as follows:

- Air filter restriction (?P) exceeds 6.25 kPa (30 in. of water)

- Engine power derating starts at the rate of 2% per 1 kPa of ?P

- Maximum derate 20%

- Event is logged when air filter restriction (?P) exceeds 6.25 kPa (30 in. of water)

These ?P specifications are typical examples. The actual values may vary depending on the application.

Derating is retained at the maximum ?P until the key start switch is cycled off and on.

NOTE: If only one filter is plugged, the ET service tool and Caterpillar Monitoring System will display the highest ?P of the two. Derating is also based on the highest ?P of the two.

Turbocharger outlet pressure sensor

The Turbocharger Outlet Pressure Sensor measures absolute pressure downstream of the aftercooler. Boost (gauge) pressure can be read with the ET service tool. This measurement is a calculation using the Atmospheric Pressure and the Turbocharger Outlet Pressure Sensors.

A failure of this sensor will cause the ECM to default to a zero boost condition. This failure can result in a 60% loss in engine power.

The function of the sensor is to enable the Air/Fuel Ratio Control which reduces smoke, emissions and maintains engine response during acceleration. The system utilizes manifold pressure and engine speed to control the air/fuel ratio. Engine fuel delivery is limited according to a map of gauge turbo outlet pressure and engine speed.

The Air/Fuel Ratio Control setting is adjustable on 3500B machine applications using the ET service tool.

Crankcase pressure sensor

The ECM uses gauge pressure measured from the Crankcase Pressure Sensor and the Atmospheric Pressure Sensor to determine whether crankcase pressure is excessive.

The ECM will warn the operator of possible damaging conditions and record adverse conditions in the memory.

A possible cause of excessive crankcase pressure could be piston damage or a piston ring failure. An early warning means that the engine can be shut down without catastrophic secondary damage.

Crankcase pressure (A) is compared with atmospheric pressure (A). The result is crankcase (gauge) pressure (i.e. pressure above ambient).

The trip points are:

WARNING 2 kPa (10 in. of water)
EVENT         3.5 kPa (17in. of water)

Engine Mounted Switches

Three EUI circuit switches are mounted on the engine:
The Low Oil Level Switch signals the ECM if the engine oil level decreases below a predetermined level. The ECM then warns the operator of possible damaging conditions and logs an event.

The Filter Differential Pressure Switch signals the ECM if the pressure across engine fuel filter is excessive and the filter needs to be changed.

The Coolant Flow Switch provides the operator with a warning if a failure in the coolant circuit causing no flow occurs. The switch contacts are normally open with no flow

Coolant flow switch

The Coolant Flow Switch, like the Oil Level Switch, is a passive sensor
no power supply) which means that the ECM cannot determine if the switch or associated circuit has failed. A system problem could be determined if coolant flow is indicated with the engine stopped or if no coolant flow is indicated with the engine running.

The functions of these switches may be checked using the status screen. The Coolant Flow Switch should indicate if flow is present. This function should be checked both with the engine running and stopped

Digital Sensors and Circuits

The following digital sensors and circuits are used on the 793C EUI fuel system:

- Wastegate Control Solenoid

- Exhaust Temperature Sensors

- Throttle Position Sensor

Wastegate control

The ECM controls turbocharger boost (on the 793C) with the Wastegate Control Solenoid.

The ECM varies the current level to the solenoid to maintain the desired boost pressure. This current, expressed as a percentage (0 to 100%), can be monitored with ET on the status screen. The ET service tool also allows the wastegate to be manually operated for testing purposes.

Both desired and actual boost pressures can be monitored. If high boost pressure is detected, a warning is generated and the engine is derated for protection against excessive cylinder pressure. A lower than normal boost pressure will also cause a warning to be generated.

ECM derates with excessive exhaust temperature

Two Exhaust Temperature Sensors are installed on the 793C. The sensors are mounted between the exhaust manifold and the turbocharger.
The ECM uses the sensors to warn the operator of possibly damaging conditions and logs an event in the memory.

An engine derate occurs on Off-highway Trucks if excessive exhaust temperatures are reached.

Throttle position sensor

The Throttle Position Sensor provides engine speed control for the operator.
At engine start-up, the engine rpm is set to low idle for two seconds to allow an increase of oil pressure before the engine is accelerated.

The Throttle Position Sensor receives 8 Volts from the Digital Sensor Power Supply at the ECM.

The Throttle Position Sensor is shown on the machine wiring side of the diagram.

NOTE: This system eliminates all mechanical linkages between the operator's engine speed controls and the governor (ECM).

Throttle position sensor signal

A Pulse Width Modulated (PWM) output signal is sent from the Throttle Position Sensor to the ECM. A PWM signal eliminates the possibility of an erroneous throttle signal due to a short causing a possible "runaway."

If a signal problem occurs, the control defaults to the desired engine speed of low idle. If the ECM detects an out-of-normal range signal, the ECM ignores the Throttle Position Sensor signal and defaults to low idle.

The sensor output is a constant frequency Pulse Width Modulated (PWM) signal to the ECM. For example, the Off-highway Truck sensor produces a duty cycle of 10 to 22% at the low idle position and 44 to 52% at the high idle position. The duty cycle can be read with some VOM's. The percent of duty cycle is translated into a throttle position of 0 to 100% by the ECM and can be read on the ET status screen.

Other applications differ in PWM values for low and high idle. These values can be found in the Troubleshooting Guide for the appropriate application.

Throttle back-up switch

The Throttle Back-up Switch provides a "limp home" mode in the event that the Throttle Position Sensor becomes inoperative.

If the ECM detects either an invalid or no signal from the Throttle Position Sensor, the Throttle Back-up Switch is automatically activated. When activated, the operator may operate the switch to raise the engine speed to 1200 rpm for as long as the switch is operated. If the Throttle Position Sensor signal is received again, the switch is deactivated.

Engine Shutdown Systems

The Ground Level Shutdown Switch is connected to the ECM through the machine and engine wiring harnesses.

The switch signals the ECM to cut electrical power to the injectors, but maintains power to the ECM.

This feature also enables the engine to be cranked without starting for maintenance purposes.

No other circuits may be connected to this system. The user defined shutdown feature may be used in conjunction with other circuits.

User defined shutdown input

The User Defined Shutdown feature (if installed) may be used to connect another device to the system to shut down the engine (such as a customer installed fire suppression system). When the shutdown input is grounded for one second, the engine will stop running. The input must be pulled down below 0.5 Volts before the ECM will recognize the shutdown signal.

Operation of the User Defined Shutdown is logged as an event and can also be shown on the ET status screen.

For example, when installed on an Off-highway Truck, this feature is programmed to function only during the following conditions:

Parking brake is ENGAGED Transmission is in NEUTRAL Machine ground speed is at ZERO
Not all machines will have this feature installed.

Ether Injection System

The ECM controls the use of ether for cold starting. The ECM uses inputs from the speed/timing and coolant temperature sensors to determine the need for ether.
The ECM cycles the ether for three seconds on and three seconds off. Actual flow is determined by engine speed and temperature. Ether injection is disabled when the coolant temperature exceeds 10°C (50°F) or engine speed exceeds 1200 rpm.

A manual mode allows ether injection when the above parameters permit. In the manual mode, a continuous flow of ether is injected. The ether injection status can be read on the ET status screen.

Demand Fan Controls

Two types of thermostatic fans are used in 3500B machine applications. Some Off-highway Trucks and Track-type Tractors are equipped with a variable speed fan drive clutch. Some Wheel Loaders are equipped with a hydraulic fan drive.

Both systems use the ECM and the temperature sensor as the engine coolant temperature reference, and both are controlled by the ECM. If an electrical failure of the system occurs, the fan will go to maximum (100%) speed.

The advantages of the systems are:


- Reduced fuel consumption in most conditions

- Reduced engine overcooling at low ambient temperatures

- Faster engine warm-up

- More engine power available at the flywheel

- Reduced noise

CAT Data Link

The CAT Data Link is the communication link between the ECM,
EPTC II, Caterpillar Monitoring System, ET Service Tool, or PC based software and other onboard/offboard microprocessor based systems. The CAT Data Link is a system which allows the various onboard systems to communicate with each other through a two wire connection. Up to 10 systems can be connected on a machine.

The CAT Data Link is used for programming and troubleshooting the electronic modules used with Caterpillar ET through the Service Tool Connector. This connector is the common access point for all onboard ECM's.

It should be noted that, if a Personality Module is not installed in the ECM or is not flash programmed, the ET Service Tool will not be able to communicate with the ECM.

Data link cables twisted to reduce RFI

The CAT Data Link is a two wire (twisted pair) electrical connection used for communication between electronic modules that use the CAT Data Link. The cables are twisted to reduce Radio Frequency Interference (RFI).

Typical systems connected by the data link are:

- ECM
- VIMS Modules
- Caterpillar ET Service Tool
- Transmission Control Module

The ECM communicates with the Caterpillar Monitoring System or Vital Information Management System (VIMS) to share engine information such as engine speed, engine oil pressure, coolant temperature, filter restriction, and electronic system faults.

Two data link systems are currently used. The CAT Data Link circuit is used for normal diagnostic and programming functions, and the ATA Data Link is used for flash programming.

Prelubrication System

The ECM controls the prelubrication system (if installed). This system uses the coolant temperature, engine speed and oil pressure as its references to determine the need for prelubrication.

The system is activated when the key start switch is turned to the start position. The system prevents starter motor engagement until the oil pressure increases.

Logged Events

Logged events listed on the appropriate ET screen are conditions which are abnormal to the operation of the engine. For example:
- High coolant temperature

- Low oil pressure

- Filter restriction

- Excessive engine speed

These events are not normally electronic problems, but might be conditions caused by a plugged radiator, low oil level, maintenance or operator deficiencies.

A list of possible events for the 3500B engine is included on the next page.
Some of the parameters listed in this presentation are used in the ET events list. They are as follows:

- High coolant temperature

- High exhaust temperature

- High aftercooler temperature

- Crankcase pressure

- Loss of coolant flow

- Low (lubrication) oil pressure (according to the oil pressure map)

- User defined shutdown

- Air filter restriction

- Fuel filter restriction

- Oil filter restriction

- Engine oil level

- Engine overspeed histogram

- High boost

- Low boost

All the above parameter values can be read on the ET status screens. Events are not logged if an electronic fault is detected.

Passwords are required to clear events. This process would normally be performed during an engine overhaul. At other times, the events should remain as a record of the engine history up to overhaul time.

APPLICATION SPECIFIC SYSTEMS
This portion of the presentation discusses application specific systems in machine applications.

The topics are:

Oil Renewal System (Off-highway Trucks) Wastegate Control System (793C).

Oil Renewal System

This system is controlled by the ECM which, depending on various parameters, injects engine oil into the return fuel line where it mixes with the fuel and is sent to the fuel tank.

Located on the right side of the engine are:

- Oil renewal injector manifold (1)

- Fuel pressure regulator (2)


The oil does not have to be changed when using the oil renewal system. When the oil renewal system is used, the engine oil filters, the primary fuel filter and the secondary fuel filters must all be changed at 500 hour intervals.

Oil flow from lube system to fuel tank

A small amount of engine oil flows from the engine block to the oil renewal injector manifold.

The oil flows from the oil renewal injector manifold into the return side of the fuel pressure regulator.

The engine oil returns to the fuel tank with the return fuel.

The engine oil mixes with the fuel in the fuel tank and flows with the fuel from the transfer pump to the EUI injectors to be burned with the fuel.

When the oil renewal system is used, the operator must pay close attention to the ADD OIL message that the VIMS provides to the operator when makeup oil must be added.

This system, which is an attachment, includes a larger capacity oil pan. If the ECM detects a low oil level, an event is logged.

Wastegate Control

An exhaust bypass (wastegate) valve (1) prevents excessive boost pressure by diverting exhaust gasses away from the turbochargers. The bypass valve is controlled by the ECM.

Brake system air pressure is supplied to the wastegate solenoid valve (2). If boost pressure exceeds a predetermined value, the ECM will energize the wastegate solenoid which sends air pressure to open the exhaust bypass valve. When the exhaust bypass valve is open, exhaust gases at the turbine side of the turbochargers are diverted to the muffler. Diverting the turbine exhaust pressure causes the turbochargers to slow down and reduce the boost pressure to the cylinders.

For diagnostic testing, the wastegate solenoid valve can be manually controlled (overridden) from minimum to maximum with the ET service tool. The status screen can be used to read the current flowing through the solenoid. 0% corresponds to a closed wastegate and 100% corresponds to fully open.

The following conditions will cause the ECM to generate a derate and log an event:

20 kPa (3 psi) above desired pressure for 15 seconds causes 10% derate

30 kPa (4 psi) below desired pressure for 15 seconds causes 10% derate

CONCLUSION

The 3500B Electronic Engine Control System is the "state of the art" in engine electronics. It combines the speed and capacity of modern computer systems, but at the same time is easy to service and maintain. Tasks such as re-rating the engine, which traditionally took four to eight hours, can be performed in minutes with this system.

The key to success with the 3500B EUI system is understanding the functions of all the components and the diagnostic tooling. This only develops with practice, working with the system, operating with ET and using all the tool functions.

EUI COLD MODES

COLD MODE TITLE                     PURPOSE             TRIP POINTS                 SENSOR

Speed Control

Elevated low idle                              Faster warm-up               < 60°C                   Coolant temperature


Fuel Limiting

Cranking limit              Improves starting by limiting fuel       < 60°C                   Coolant temperature

                                     Prevents over-fuelling during start-up


Cold Mode Cutout      Cuts out dead cylinders during cold,
                                       low load, low speed conditions           < 60°C                 Coolant temperature
                                                                                                   < 1300 rpm
                                                                                                   < 25% throttle

Injection Timing

Cold Mode Timing        Optimum timing for cold running       < 60°C                 Coolant temperature

                                         Reduces white smoke

Ether Injection

Ether injection                   Starting aid                                       10°C                   Coolant temperature

ECM PRESSURE CALCULATIONS

MEASUREMENT                   MEASURED BY RESULT


1. Atmospheric pressure                    atmospheric sensor =  ambient press (absolute)


2. Air filter differential             atmospheric - turbo inlet =  filter ? pressure


3. Boost                                turbo outlet - atmospheric =  boost (gauge pressure)


4. Manifold press. (A)                   turbo outlet sensor =  boost (absolute pressure)


5. Oil pressure                             oil press - atmospheric =  oil press (gauge pressure)


6. Oil filter differential            oil press unfiltered - oil press filtered =  oil filter ? pressure


7. Crankcase pressure (A)         crankcase pressure - atmospheric  = crankcase pressure (gauge                                                                                                                                                      pressure)

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