C11/C13 ACERT ENGINE ON GRADER 16M CATERPILLAR

C11/C13 ACERT™ ENGINE

The C11 ACERT™ and C13 ACERT™ engines utilize the A4 Electronic Control Module (ECM) engine control and is equipped with an Air to Air Aftercooler (ATTAC) intake air cooling system.



The Engine ECM utilizes the ADEM IV to control the fuel injector solenoid and to monitor fuel injection.  The fuel is delivered through a Mechanical Electric Unit Injection (MEUI) system. ACERT™ Technology provides an advanced electronic control, a precision fuel delivery, and refined air management.

 The C11 engine is an in-line six-cylinder arrangement with a displacement of 11.1 L.  The C13 engine is also an inline six-cylinder arrangement with a displacement of 12.5 L.

The C11 and C13 ACERT™ engines meet all US Environmental Protection Agency (EPA) Tier III Emission Regulations for North America and Stage IIIa European Emission Regulations.

The engine performance specification for the 14M are as follows:

- Serial No. Prefix: RSX
- Performance Spec: 0K6245
- Hp range with VHP: 183 kW - 194 kW (245 hp - 260 hp)
- Hp range with VHP Plus 183 kW - 209 kW (245 hp - 280 hp)
- Full Load rpm: 1800
- Low Idle rpm: 800
- High Idle rpm: 2150
- Boost at Full Load rpm: 23 Psi


The engine performance specification for the 16M are as follows:

- Serial No. Prefix: MHX
- Performance Spec: 0K7190
- Hp range with VHP: 221 kW - 233 kW (297 hp - 312 hp)
- Hp range with VHP Plus 221 kW - 248 kW (297 hp - 332 hp)
- Full Load rpm: 2000
- Low Idle rpm: 800
- High Idle rpm: 2150
- Boost at Full Load rpm: 18 Psi

Engine Electrical Block Diagram

This block diagram of the engine electrical system shows the components that are mounted on the engine. The components provide input signals and receive output signals from the Engine Electronic Control Module (ECM).

Based on input signals, the Engine ECM energizes the injector solenoid valves to control fuel delivery to the engine and energizes the cooling fan solenoid valve to adjust fan speed.

The two interface connectors provide electrical connections from the engine to the machine including the CAN Data Link and the Cat Data Link.

Some of the components connected to the Engine ECM through the connectors are:  throttle pedal position sensor, throttle mode switch, and the ground level shutdown switch.

Input Components:

Camshaft speed timing sensor - The speed timing sensor sends a fixed voltage level signal to the Engine ECM in order to determine the engine speed, direction, and timing.

Crankshaft speed timing sensor - The speed timing sensor sends a fixed voltage level signal to the Engine ECM in order to determine the engine speed, direction, and timing.

Atmospheric pressure sensor - This sensor is an input to the Engine ECM and is used as a reference for air filter restriction. Also, the sensor is used to supply information to the Engine ECM during operation at high altitude.

Turbo inlet pressure sensor - This sensor is an input to the Engine ECM to supply information about the air restriction before the turbocharger.  The ECM uses this information for engine derates and logged events.

Intake manifold air temperature sensor - This sensor supplies air temperature data at the intake manifold to the Engine ECM.  The ECM uses this information for engine derates and logged events.

Fuel differential pressure switch - This switch relays information to the ECM that the fuel pressure at the output of the filter base is restricted in comparison to the inlet pressure.

Coolant temperature sensor - This sensor is an input to the Engine ECM supplying information on the temperature of the engine coolant.  The ECM uses this information for fan solenoid current, high coolant temperature warnings, engine derates for high coolant temperature, or logged events.

Fuel temperature sensor - This sensor sends fuel temperature data to the Engine ECM.  The ECM uses this information for engine derates and logged events.

Engine oil pressure sensor - This sensor is an input to the Engine ECM to supply an information warning for low oil pressure, engine derates for low oil pressure, or logged events.

Throttle pedal position sensor - This sensor sends the throttle position to the Engine ECM in order to increase or decrease the fuel supply to the injectors.

Key switch ON (+B) - The Key ON input to the Engine ECM enables the ECM for operation and is recognized by any ECM on the machine.

Ground level shutdown switch - This switch is an input to the Engine ECM.  This input disables fuel injection when the engine is running or at engine start-up.

Intake manifold air pressure sensor - This sensor is an input to the Engine ECM to supply information about the air pressure into the intake manifold.

Throttle mode switch - The switch relays information to the ECM for manual and automatic throttle controls.

Throttle resume/decel switch - The switch relays information to the ECM to decel or resume engine rpm.

Throttle set/accel switch - The switch relays information to the ECM to set or accelerate engine rpm.

Timing calibration connector - Connector used for timing the engine with Cat ET.

Output Components:

+5 Volt - Regulated supply voltage for the sensor inputs to the Engine ECM.

+8 Volt - Regulated supply voltage for the sensor inputs to the Engine ECM.

Throttle sensor voltage - Voltage supply for the throttle position sensor.

Fan solenoid valve - Proportional solenoid valve that controls the signal pressure to the brake and hydraulic fan pump in order to meet the varying cooling requirements of the machine.

Ether solenoid valve - The Engine ECM energizes the solenoid valve to inject ether into the intake manifold.

Fuel pump relay - Relay used to turn the electric fuel pump on when the key start switch is turned to the ON position.

The Engine ECM (1) is located on the left side of the engine.  The Engine ECM has a 70-pin connector and a 120-pin connector.  The connectors are identified as "J1" and "J2."  Be sure to identify which connector is the J1 or J2 connector before performing diagnostic tests
Occasionally, Caterpillar will make changes to the internal software that controls the performance of the engine.  These changes can be performed by using the WinFlash program that is part of the laptop software program Cat ET.  Cat ET is used to diagnose and program the electronic controls used in Caterpillar products.  If using the WinFlash program, a "flash" file must be obtained from Caterpillar and uploaded to the ECM.

The crankshaft speed/timing sensor (1) is located at the bottom of the timing gear cover.  The crankshaft sensor is the primary speed sensor reporting to the Engine ECM with the engine speed and position of the crankshaft.  The crankshaft speed/timing sensor sends a frequency signal to the Engine ECM on contact J2-35 and contact J2-25 indicating crankshaft speed.  The speed/timing sensors serve four functions in the engine electronic control system
1. Engine speed measurement

2. Engine timing measurement

3. TDC location and cylinder number identification

4. Reverse rotation protection


If the signal from the crankshaft speed timing sensor is lost or intermittent, normally a
CID 0190 FMI 08 Engine Speed Abnormal will be logged and can be viewed through Cat ET

NOTE:  If the engine is running and the signal from the crankshaft is lost, a slight change in performance is noticed during change over to the camshaft sensor.

The atmospheric pressure sensor (1) is located on the left side of the machine on the engine. The Engine ECM uses the sensor as a reference for air filter restriction and derating the engine under certain parameters. All pressure sensors in the system measure absolute pressure and, therefore, require the atmospheric pressure sensor to calculate gauge pressures
The atmospheric pressure sensor is one of the many sensors that require a regulated 5.0 VDC for the sensor supply voltage. The atmospheric pressure sensor outputs a variable DC voltage signal.

The camshaft speed/timing sensor (2) is located below the atmospheric pressure sensor.  Under normal operation, the camshaft speed/timing sensor determines the No. 1 compression timing prior to the engine starting.  If the camshaft sensor is lost, a CID 342 MID 08 Secondary engine speed signals abnormal code is active and the crankshaft sensor will time the engine with an extended starting time.  The engine will run rough until the Engine ECM determines the proper firing order using the crankshaft sensor only.  In the case that the signal from both engine speed sensors is lost, the engine will not start.  During a running condition, the engine will shutdown.

The sensor serves as a back-up for the crankshaft speed/timing sensor.  If the crankshaft speed/timing sensor fails, the camshaft speed/timing sensor allows for continuous operation.

Engine Speed/Timing Calibration Port

If the engine requires timing calibration, a timing sensor (magnetic pickup) is installed in the engine block at location (2) and connected to the timing calibration connector (1) located above the Engine ECM.

Using the Cat ET service tool, the timing calibration is performed automatically. The desired engine speed is set to 800 rpm. This step is performed to avoid instability and ensures that no backlash is present in the timing gears during the calibration process.

Timing calibration improves fuel injection accuracy by correcting for any slight tolerances between the crankshaft, timing gears, and timing wheel.

Timing calibration is normally performed after the following procedures:


- ECM replacement

- Engine overhaul

- Active code that requires a timing calibration

Fuel System

Fuel is drawn from the fuel tank through the primary fuel filter and water separator by a gear-type fuel transfer pump.  The fuel transfer pump then directs the fuel through the secondary fuel filter.

The fuel then flows to the cylinder head.  The fuel enters the cylinder head and flows into the fuel gallery, where it is made available to each of the six MEUI fuel injectors. Any excess fuel not injected leaves the cylinder head and flows back to the secondary fuel filter.  Then, the excess fuel flows past the fuel pressure regulator.

The fuel pressure regulator is a check valve that is installed in the secondary fuel filter.  The fuel pressure regulator maintains fuel system pressure between the fuel transfer pump and the fuel pressure regulator.

From the fuel pressure regulator, the excess fuel flow returns to the fuel tank.  The ratio of fuel used for combustion and fuel returned to tank is approximately 3:1 (i.e. four times the volume required for combustion is supplied to the system for combustion and injector cooling purposes)
A differential pressure switch is installed in the secondary fuel filter base and will alert the operator of a fuel filter restriction.  The differential pressure switch compares the filter inlet pressure to the filter outlet pressure.  When the difference in the inlet and outlet pressures causes the switch to activate, the Engine ECM will signal Messenger to warn the operator the fuel flow is probably restricted.

A fuel pressure sensor is installed in the secondary fuel filter base and will signal the Engine ECM of a high fuel pressure.  If the fuel pressure exceeds a pressure of 758 kPa (110 psi) the Engine ECM will log a E096 code.

In the case of a logged high fuel pressure Event, check the following Fuel System's Components:

- Inspect the fuel transfer pump pressure relief valve that is in the body of fuel transfer pump.  Check    for damage to the spring or to the valve assembly.

- Verify that the pressure regulating valve in the fuel filter manifold is operating correctly. Check for     damage or for dirt in the valve assembly.

Check the return line from the fuel filter base to the fuel tank for damage or collapse

The top visual is the 14M.  The lower visual is the 16M

The fuel transfer pump (1) is a gear pump that is located near the balancer at the front of the engine.  The fuel transfer pump is driven by the front gear train.  Fuel is drawn from the primary fuel filter and water separator by the fuel transfer pump and is directed to the secondary fuel filter.

The fuel transfer pump incorporates a check valve.  The check valve allows fuel to flow around the gears of the pump when the fuel system is primed. A relief valve (not shown) is also installed in the fuel transfer pump.  The relief valve limits the maximum fuel pressure in the fuel system.

The top visual is the 14M.  The lower visual is the 16M.

The primary fuel filter (1) is mounted near the left rear side of the engine.  The primary filter contains a water separator which removes water from the fuel.  Water in a high pressure fuel system can cause premature failure of the injector due to corrosion and lack of lubrication. Water should be drained from the water separator daily, using the drain valve that is located at the bottom of the filter

The primary filter has an electric fuel priming pump integrated into the filter base. The priming pump is activated automatically by the Engine ECM. The electric fuel priming pump is used to fill the fuel filters with fuel after they have been replaced.

The relay for the electric fuel priming pump is energized for 120 seconds when one of the following conditions occur:

- Key start switch is turned to the ON position (engine not running)

- When the engine is cranking

- After the engine has been shutdown

The fuel system is also equipped with a high efficiency secondary fuel filter (2).  This filter is located on the left side of the engine.  The fuel regulator (not shown) is integrated into the secondary fuel filter base.  The fuel pressure regulator regulates the the flow of fuel from the fuel gallery

Power Derate

The illustration above defines the power derate in relation to the rated torque map and the default torque map.  The power derate is a percentage reduction from the rated power at a given engine speed toward the default map at the same rpm.

Power is unchanged until the requested power exceeds the derated level.  The maximum power during a derate is calculated as:

Maximum Power Output = Rated Power - (Rated Power - Default Power) * Derate Percentage

For example, if the engine has a maximum rated power of 500 hp and a 100 hp default torque map with a 50% derate, the engine will have 300 hp output power.  If 250 hp was needed, then the operator will not notice any change.  If however, 400 hp was needed, there would be only 300 hp available due to derates.

300 hp = 500 hp - (500 hp - 100 hp) X 50% (.50)

The engine coolant temperature sensor (1) is located on the front of the engine, below the water temperature regulator housing. The input to the Engine ECM from this sensor on contact J2-13 provides the following temperature information:
- The Instrument Cluster coolant temperature gauge and the high coolant temperature warning alert       indicator LED on the Caterpillar Instrument Cluster.

- The temperature input for the ether aid system operation.

- The Caterpillar Electronic Technician (Cat ET) status screen coolant temperature indication.

NOTE: If the coolant temperature exceeds 110° C (230° F) an event is logged in the Engine ECM. Also, the ECM will automatically derate the fuel delivery to protect the engine.

The coolant temperature sensor measures the temperature of the coolant
When the temperature of the coolant exceeds 110° C (230° F), the Engine ECM will initiate a Level 1 Warning.

When the temperature of the coolant exceeds 111° C (231° F),  the Engine ECM will initiate a Level 2 Warning. At 111° C (231° F) the Engine ECM will initiate a 25% derate.  Refer to the illustration for the remainder of the high engine coolant temperature derates. At 100% derate, the engine available power will be approximately 50%.

The engine oil pressure sensor (1) is located on the left side of the engine near the Engine ECM (2).  The sensor monitors the pressure of the engine oil.
The sensor receives a +5 VDC signal from the Engine ECM on contact J2-72 and sends an oil pressure signal to the ECM on contact J2-28.

The Engine ECM will use the information supplied by the oil pressure sensor to output warning levels to Messenger and derate the engine.

This illustration shows a graph with the two different warning levels for low oil pressure
When the oil pressure is below the blue line (154 kPa @ 1600 rpm) (22 psi @ 1600 rpm), the monitoring system will enable the low oil pressure Level 1 Warning.  Change machine operation or perform maintenance to the system, in the event of a warning.

When the oil pressure is below the red line (104 kPa @ 1600 rpm)(15 psi @ 1600 rpm), the monitoring system will enable the low oil pressure Level 3 Warning.  The operator should immediately perform a safe engine shutdown, in the event of a Level 3 warning.

Also, with the Level 3 Warning, the Engine ECM initiates a 35% engine derate.

If the signal between the Engine ECM and the oil pressure sensor is lost or disabled, the Engine ECM will initiate a low engine oil pressure Level 1 Warning.

The intake manifold pressure sensor/turbocharger outlet pressure sensor (1) is located on the left side of the engine.  The input data from the intake manifold pressure sensor/turbocharger outlet pressure sensor to the Engine ECM is used by the ECM to electronically control the air fuel ratio.  This feature allows very precise smoke control, which was not possible with mechanically governed engines.  The intake manifold pressure sensor/turbocharger outlet pressure sensor also allows boost pressure to be read using the Cat ET.  The intake manifold pressure sensor/turbocharger outlet pressure sensor receives a +5 VDC signal from the Engine ECM on contact J2-72 and sends a signal to the ECM on contact J2-15
The intake manifold air temperature sensor (2) is also located on the left side of the engine. The air temperature sensor provides air temperature data on contact J2-56 to the Engine ECM to warn the operator of potentially damaging conditions.  This sensor is also used for derating the engine at high temperature and for use by Messenger.

The intake manifold air temperature sensor measures the temperature of the air that is flowing to the intake manifold.  The sensor is used to initiate warning levels and engine derates.
After the engine is running for at least 3 minutes and if the intake manifold air temperature goes above 82° C (180° F), the Engine ECM will initiate a Level 1 Warning.

After the engine is running for at least 3 minutes and if the intake manifold air temperature goes above 86° C (187° F), the Engine ECM will initiate a Level 2 Warning.  With the Level 2 Warning, the Engine ECM signals the engine to initiate a 3% derate.  This derate will have a 20% upper limit.

The turbocharger inlet pressure sensor (1) is located in a tube between the air cleaners and the turbocharger.  The Engine ECM uses the turbocharger inlet pressure sensor in combination with the atmospheric pressure sensor to determine air filter restriction.  The Engine ECM provides the input signal to the monitor system, which informs the operator of the air filter restriction
The sensor receives a +5 VDC signal from the Engine ECM on contact J1-2 and sends a signal to the ECM on contact J1-15.

The turbo inlet pressure sensor measures the restriction of the air inlet that is flowing to the inlet of the compressor housing of the turbocharger.  When the pressure difference between the turbo inlet pressure sensor and the atmospheric sensor read a difference of 9.0 kPa , the
Engine ECM will derate the engine approximately 2%.  The Engine ECM will then derate the engine 2% more for every 1 kPa difference up to 10%.

Typically the atmospheric pressure sensor is 100 kPa at sea level. As the air restriction increases, the difference will increase.  The first derate will occur when the difference is approximately (100 kPa minus 91 kPa.= 9 kPa).

If the air inlet restriction is 92.5 kPa (a pressure that is between 7.5 kPa and 9 kPa) for 10 seconds, the Engine ECM will initiate a Level 1 Warning.

If the air restriction goes to the point that the turbo inlet pressure sensor sees a difference of 91.1 kPa (a pressure that is 9.0 kPa) for 10 seconds, then the Level 2 Warning will occur and the engine will derate.

NOTE:  This air inlet restriction derate is a latching derate.  The derate will remain active until the machines is shut down.

The differential fuel pressure switch (1) is located in the top of the secondary fuel filter housing on the left side of the engine.  This switch indicates restriction in the fuel filter and provides an input to the Engine ECM on contact J2-62. A warning is also sent by the Engine ECM to Messenger.
The fuel pressure sensor (2) is located in the top of the secondary fuel filter housing on the left side of the engine.  This sensor is used to monitor fuel pressure and receives a +5 VDC signal from the Engine ECM on contact J2-72 and sends a signal to the ECM on contact J2-40.

The fuel temperature sensor (3) provides an input to the Engine ECM on contact J2-62.  The Engine ECM uses the fuel temperature measurement data from the fuel temperature sensor to make corrections to the fuel rate to maintain power regardless of fuel temperature (within certain parameters).  This correction feature is called "Fuel Temperature Compensation.

This illustration shows the graph for the warning and the derates map for the fuel temperature. When the fuel temperature exceeds 90° C (194° F), the Engine ECM will activate a Level 1 Warning.  When the fuel temperature increases to 91.0° (196° F) a Level 2 Warning will be initiated by the Engine ECM. At the same time, the engine will derate to 12.5%.  If the fuel temperature exceeds 92° C (198° F), the engine will be derated to 25%.
A fuel temperature sensor open circuit will derate the engine to 12.5%.

When the differential pressure switch recognizes a fuel pressure of 103 kPa (15 psi) for 3 minutes, the Engine ECM will initiate a Level 1 Warning.
When the differential pressure switch recognizes 103 kPa (15 psi) across the filter for 4 hours, the Engine ECM will initiate a Level 2 Warning. With the Level 2 Warning initiated, a 17.5 % derate is applied to the engine. After 1 second, the Engine ECM will initiate a second derate of 17.5%.  The total derate will be 35%.

NOTE:  This feature will be disabled when the fuel temperature is below 30° C (86° F).

An engine derate can occur due to a estimated (virtual) high exhaust gas temperature.  The Engine ECM monitors barometric pressure, intake manifold temperature, and engine speed to estimate exhaust gas temperature.  Certain conditions (high altitude, high ambient temperatures, high load and full accelerator pedal throttle, barometric pressure, intake manifold temperature, and engine speed) are monitored to determine if the engine derate should be enabled.  The Engine ECM determines a maximum fuel delivery percentage to maintain safe maximum power output under load.  This calculation is new to the off-road Tier III engines and is used in place of the previous altitude compensation derate strategy.
This event is to inform the mechanic that a derate has occurred because of operating conditions. Generally, this is normal and requires no service action.

The Engine ECM will process all derate inputs in the highest derate priority selector.   The most critical derate condition input will be used to adjust fuel system delivery limiting engine power to a safe level for the conditions in which the product is being operated, thereby preventing elevated exhaust temperatures.

The virtual exhaust temperature derate will log a 194 event code.  The derate will enable a Level 1 Warning and eventually a Level 2 Warning.  The level of the warning will depend on the conditions that are sent to the Engine ECM.

The following conditions must be met to initiate a virtual exhaust temperature derate.


- No CID 168 01 FMI (low battery voltage to the Engine ECM) are active.

- No active intake manifold pressure sensor faults.

- No active atmospheric pressure (barometric) sensor faults.

- No +5 V sensor voltage codes active.

- The virtual exhaust temperature derate must be the highest derate.

- More fuel is being requested than the virtual exhaust temperature derate will allow.

This derate is triggered by the information inferred by the Engine ECM, rather than an individual sensor as with the previous single derate strategies.  If you think this derate is possibly being imposed incorrectly check for event codes on high intake manifold temperature. Correct any codes first. Also, make sure the aftercooler is unobstructed.  For additional information about troubleshooting, refer to the troubleshooting guide for the particular engine that is being serviced.

The ether start control has changed with the introduction of the Tier III machines. The ether system (if equipped) is now automatically controlled by the Engine ECM. Ether control also now utilizes one continuous shot instead of a one shot application.
The Engine ECM energizes the ether solenoid (arrow) for a predetermined amount of time that is based on ECM software.  The ECM monitors the coolant temperature sensor, air temperature sensor, and the atmospheric pressure sensor to determine the temperature and altitude of the machine.  Based on these inputs, the ECM will determine if ether is required.

The ether injection system can be enabled or disabled using Cat ET.

The radiator (1) and air to air aftercooler (2) now sit side by side in the cooling package.  The C11/C13 is equipped with a wastegate turbocharger which provides higher boost over a wide range, improving engine response and peak torque, as well as outstanding low-end performance.
NOTE:  The wastegate is preset at the factory.

Throttle mode switch (1) allows the operator to select between two different throttle modes:
- Automatic Mode:  When top of switch (1) is depressed, the throttle mode is set to automatic.  In          automatic mode, the operator can set the engine rpm with the throttle pedal (not shown) or with          set/accelerate switch (2).  If the operator wants to decrease the engine rpm, the operator can depress    or depress and hold the resume/decelerate switch (3) to decrease engine rpm.  If the brake pedal is      depressed at any time when the automatic mode has been selected, the engine will return to low          idle.  If the switch (3) is depressed, the engine rpm will return to the previous set point.

- Manual Mode:  When the bottom of switch (1) is depressed, the throttle mode is set to manual            mode. The operator can set or decrease the engine rpm in the same way as automatic mode.  The        brake pedal does not decrease the engine rpm to low idle.  To return the engine to low idle, the            switch (1) should be placed in the OFF position (center).

Engine Idle Management

Cool Engine Mode - In cold weather operation, the engine rpm will be set to 1000 rpm in  order to generate additional engine heat, keeping the engine warmer.  This mode monitors the coolant temperature and the intake manifold temperature.  When the coolant temperature is below 80° C (176° F) or the intake manifold temperature is below 15° C (60° F) and the cool engine mode is enabled, the machine will time out for 10 minutes. After ten minutes, if the coolant temperature is below 70° C (158° F) and the machine has been the in cool engine mode, the engine will be in the cool engine mode.  If the machine has not been in cool engine mode but the intake manifold temperature is less than 5° C (41° F), the engine will go into the cool engine mode.

Low Voltage Mode - In this mode, the engine will ramp up to 1000 rpm when the battery voltage drops below 24.5 volts for more than five minutes. When the battery voltage is greater than 24.5 volts, the engine idle will return to low idle.

NOTE: The Engine Idle Management Strategies can not be reconfigured with Cat ET.


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