the natural gas engine characteristics - … · the series 50g/60g engine is spark-ignited natural...

8 THE NATURAL GAS ENGINE CHARACTERISTICS

Section Page

8.1 NATURAL GAS ENGINE COMPONENTS ............................................... 8-3

8.2 ELECTRONIC SYSTEM .......................................................................... 8-9

(Rev. 9/04) All information subject to change without notice.

8-2 From Bulletin 2-50G/60GTS-04 6SE482 0409 Copyright © 2004 DETROIT DIESEL CORPORATION

SERIES 50G/60G TROUBLESHOOTING MANUAL

8.1 NATURAL GAS ENGINE COMPONENTS

See Figure 8-1 and Figure 8-2 for the identification of the series 60G Natural Gas components.

1. Automatic Belt Tensioner 5. Low Pressure Regulator

2. PSV 6. DDEC IV ECM

3. Fuel Mixer 7. SNEF Module

4. Throttle Plate Actuator

Figure 8-1 Natural Gas Components for the Series 60G Engine, Model6067–TKG8 (Sheet 1 of 2)

All information subject to change without notice. (Rev. 9/04)

6SE482 0409 Copyright © 2004 DETROIT DIESEL CORPORATION From Bulletin 2-50G/60GTS-04 8-3


1. Insulated Exhaust Manifold 3. Water-cooled Turbocharger Center Section

2. Coil over Plug Ignition System 4. Insulated Turbine Housing





See Figure 8-3, Figure 8-4, Figure 8-5, and Figure 8-6 for the identification of the Series 50GNatural Gas components.


2. Low Pressure Regulator





1. Insulated Turbine Housing 5. Coil over Plug Ignition System

2. Water-cooled Turbocharger Center Section 6. Fuel Mixer

3. Wastegate Actuator 7. Automatic Belt Tensioner

4. Insulated Exhaust Manifold






2. Low Pressure Regulator

Figure 8-5 Natural Gas Components for the Series 50G Engine, Model6047–MKG8 (Sheet 1 of 2)




1. Insulated Turbine Housing 5. Coil over Plug Ignition System

2. Water-cooled Turbocharger Center Section 6. Fuel Mixer

3. Wastegate Actuator 7. Automatic Belt Tensioner

4. Insulated Exhaust Manifold

Figure 8-6 Natural Gas Components for the Series 50G Engine, Model6047–MKG8 (Sheet 2 of 2)




8.2 ELECTRONIC SYSTEM

This section describes the function and installation requirements for the electronic system of DDCSeries 50G/60G Engine. A simple installation may require a basic understanding of electricalcircuits while a more comprehensive electrical or electronics background is required to access allthe capabilities of Detroit Diesel Electronic Controls (DDEC®).

The DDEC IV system is similar to the diesel engine controls in function and appearance. Thesystem optimizes control of engine functions which affect fuel economy, driveability, andemissions. DDEC IV provides the capability to protect the engine from serious damage resultingfrom conditions such as high engine temperatures, low oil pressure, combustion knock, etc. It iscapable of the same vehicle interface controls as the diesel engine such as door interlock, high andlow idle, cruise control, etc. Engine and vehicle management options such as ProDriver are alsoavailable. OEM supplied hardware and DDC supplied hardware are required to install DDEC IV.

The Electronic Control Module (ECM) receives electronic inputs from sensors on the engineand vehicle and uses the information to control engine operation. It controls spark ignition andthrottle plate position based upon predetermined calibration tables in its memory. Portableequipment facilitates access to DDEC IV diagnostic capabilities. The Diagnostic Data Reader(DDR) requests and receives engine data and diagnostic codes. This equipment provides manyunique capabilities including parameter versus engine speed (or time), printer output, and datasnapshot. The DDR also provides limited programming capability. DDEC IV provides threeindustry standard serial data links: SAE Standards J1587, J1922, and J1939. SAE standard J1587provides two-way communications for the diagnostic equipment and vehicle displays. SAEstandards J1922 and J1939 provide control data to other vehicle systems such as transmissionsand traction control devices.




8.2.1 OEM Supplied Hardware Requirements

The minimum OEM supplied hardware required is listed in Table 8-1. Refer to DDEC IVApplication and Installation, 7SA742 for additional information.

Hardware Description

Vehicle Interface Harness Assembly (VIH) Connects the vehicle functions to the ECM.

ECM Power Harness Assembly Connects battery power (12/24 V) and ground to theECM and includes fuse(s) or circuit breaker(s).

Coil Power Harness Provides power to the engine ignition coils.

OEM Sensor Power Harness Assembly Provides power (12 V only) to the Pulse Width ModulatedStepper Motor Valve (PSV), Signal Noise EnhancementFilter (SNEF) module, throttle and oxygen sensorinterface module. This harness connects to a pigtail onthe Engine Sensor Harness (ESH).

Fuel Shutoff Harness Connects to the engine-side fuel shutoff solenoid andprovides power to the fuel shutoff valve. (DDEC switch,12/24 V).

OEM Sensor Ground Harness Assembly Provides ground to the PSV, throttle and Oxygen SensorInterface Module. This harness connects to a pigtail onthe ESH.

Ignition Switch Controls 12/24 V ignition source.

Check Engine Light (CEL) Mounted in instrument panel. Indicates requiredmaintenance. Light is yellow.

Stop Engine Light (SEL) Mounted in instrument panel. Indicates engine shutdowncondition. Light is red.

Coolant Level Sensor (CLS) Mounts in radiator top tank or remote surge tank.

Table 8-1 Minimum OEM Supplied Hardware




8.2.2 DDC Supplied Hardware Requirements

The minimum DDC supplied hardware required is listed in Table 8-2. Refer to DDEC IVApplication and Installation, 7SA742 for additional information.

Hardware Description

Engine Sensor Harness Facilitates the receipt of input and output signals,controlling the fuel injection process and engine speed.

Oxygen Sensor Harness Connects the oxygen sensor to the interface module. Itis a ship loose item (Gas only).

Oxygen Sensor Provides a signal proportional to air/fuel ratio. This is aship loose item.

Exhaust Temperature Sensor Warns against malfunction that causes excessiveexhaust temperature. This is a ship loose item(Gas only).

Table 8-2 Minimum DDC Supplied Hardware

8.2.3 INSTALLATION REQUIREMENTS

The Series 50G/60G DDEC installation requirements are the same as those published in theDDEC IV Application and Installation manual except for the specifics shown in this manual.Refer to DDEC IV Application and Installation, 7SA742 for additional information.

8.2.3.1 Dedicated Power and Ground Requirements

The wires listed in Table 8-3 require dedicated power and grounds.

Wire Number Description

956 Throttle Ground

443 SNEF Power (Ignition Switched)

150 PSV Ground

446 PSV Power (Ignition Switched)

957 Oxygen Sensor Interface Module Ground

444 Oxygen Sensor Interface Power (Ignition Switched)

445 Throttle Power (Ignition Switched and DDEC Switched)

Table 8-3 Wires Requiring Dedicated Power and Ground




8.2.3.2 Relay Powered Throttle

Throttle power actuation will be done through an OEM supplied relay using either 12 or 24 V.Wire 561 (High-Side Digital Output), will provide ECM power (12 or 24 V) to trigger the relay.A dedicated 12 or 24 V power source will travel through the relay to wire 445 to the throttle.Wires 561 and 445 are show on the main wiring diagram layout and their individual connectordiagram layouts (see Figure 8-7).

Figure 8-7 OEM Sensor Power Harness




8.2.3.3 Relay Powered Fuel Shutoff Valves

Electronically-controlled fuel shutoff solenoid valves are required on the high pressure side ofthe fuel system (typically at the fuel tanks) and the low pressure side of the fuel system near theengine. The OEM is responsible for the high pressure shutoff valves. DDC will provide theengine-side solenoid valve (12 or 24 V valves are available). All electronic fuel shutoff solenoidvalves must be DDEC controlled.

DDEC control of the fuel shutoff solenoid valves will be done through an OEM supplied relayusing either 12 or 24 V. Wire 562 (High-Side Digital Output) will provide ECM power, either 12or 24 V, to trigger the relay. A dedicated 12 or 24 V power source will travel from the relay tothe solenoid valves (see Figure 8-8). The tank-side solenoids and the engine-side solenoid mustbe controlled in this manner. Separate relays can be used for the tank-side solenoids and theengine-side solenoid, as long as they are triggered by wire 562.

Figure 8-8 Fuel Shutoff Harness




8.2.4 ELECTRONIC CONTROL MODULE

The Series 50G/60G Engine is spark-ignited natural gas fueled engines that use the DDECsystem. The engine-mounted ECM includes control logic to provide overall engine management.See Figure 8-9.

Figure 8-9 Electronic Control Module

The ECM continuously performs self diagnostic checks and monitors other electrical systemcomponents. System diagnostic checks are made when the ignition is enabled and continuethroughout all engine operating modes.

NOTICE:

A diesel ECM and a natural gas ECM cannot be interchanged.An ECM is programmed for either diesel fuel with dieselcalibration or natural gas with gas calibration. To interchangethe two types of ECM’s could cause engine damage.

The ECM hardware for the Series 50G/60G engine is unique.




8.2.5 Ignition System

The Series 50G/60G engine uses an Integrated Coil and Electronics (ICE) direct ignition systemthat includes a coil for each cylinder pair and an ignition module within each encapsulatedassembly. During engine operation, the DDEC ECM sends trigger signals to the ICE modules,which direct high current pulses through the coils resulting in secondary voltages of 30,000 to50,000 volts traveling through the ignition boots to the spark plugs. The ICE system provideshigh voltage directly to each spark plug electrically, not mechanically, as does a distributor.

NOTICE:

The Series 50G/60G spark ignition system can generatevoltages as high as 50,000 V. High voltage fast pulses from thecoil can create broad band noise, Radio Frequency Interference(RFI), and Electromagnetic Interference (EMI). RFI/EFI candisrupt vehicle electrical/electronic systems with varyingdegrees of severity. Use the guidelines in this publication tokeep the ignition RFI/EMI down to acceptable levels.

Criteria for the Ignition System:

Ground are essential straps for conductive connections between individual metal partsin the vehicle.The Series 50G/60G Engine Ignition System requires a 12 V supply to the ignition coilswhich must be sourced directly from the battery or equivalent bus bar.

Use the following guidelines when installing a Series 50G/60G engine in a vehicle:

1. Make sure the following points are ground strapped together: Body to chassis, chassis tostarter ground, and starter ground to engine block.

NOTE:This practice ensures that none of the vehicle’s metal parts are at different voltagepotentials.

2. Route all electrical wiring at a maximum distance away from ignition coils, ignitionwires, and spark plugs.

3. Replace any ignition components that show signs of deterioration and check the plugs,plug wires, and coil resistances to see if they are within specifications. Refer to Series60 Service Manual, 6SE483, or Series 50 Service Manual, 6SE50, for ignition systemspecifications.

NOTE:Suspect or marginal ignition components can generate high levels of RFI/EMI.




8.2.5.1 Engine Protection

The Series 50G/60G engine protection system is similar to the DDEC diesel engine protectionsystem, with the addition of natural gas engine specific protection. Just like the diesel ECM, thenatural gas ECM monitors all engine sensors and electronic components, and recognizes systemmalfunctions. If a critical fault is detected, the CEL and SEL illuminate and a malfunction codeis logged into the ECM’s memory.

The additional Series 50G/60G protection types are as follows:

High intake manifold pressureHigh intake manifold air temperatureHigh engine knock levelHigh exhaust temperatureThrottle actuator fault protectionDDEC sensor supply voltage fault protection

NOTE:All other engine protection functions are identical to diesel including engine overrideand logging of fault codes.

8.2.5.2 Engine Critical Fault

In the event that an engine critical fault has been detected, the following sequence will occur:

1. The CEL illuminates.

2. The SEL illuminates if any condition exceeds its safe operating level.

3. The throttle actuator ramps down engine power.

4. The vehicle gas supply shutoff solenoid is set to OFF.

5. PSV closes.

6. The ignition system shuts down.

8.2.5.3 Application Code System

The Detroit Diesel Application Code System (ACS) was initiated along with the introduction ofDDEC III. The application code system includes all application-related DDEC parameters. TheApplication Engineering department has developed the list of parameters and default parametersthat are selected by Product Distribution for each application group. New 6N4C applicationcodes are required for the Series 50G/60G engine due to the differing application requirementsversus the standard diesel. For example, the Series 50G/60G engine requires the use of aDDEC-controlled fuel solenoid shutoff valve. There is no option for fuel shutoff available onthe standard diesel controls.




8.2.6 Pulse Width Modulated Stepper Motor Valve

The PSV is used to bias gas flow to the venturi mixer as a means of Air/Fuel (A/F) ratio control(see Figure 8-10). The PSV is electrically connected to the ECM and 12 V battery power throughan 8-pin connector that mates to the ESH. The PSV supplies a gas valve position analog signal toDDEC which can be monitored using the DDR. The signal indicates valve opening position. Adiagnostic signal is supplied to DDEC for loss of command signal, piston obstruction or valveelectronics failure.

1. PSV 5. Fuel Mixer

2. Bolt 6. O-rings

3. Washer 7. Fuel Transfer Tube

4. PSV O-ring

Figure 8-10 Pulse Width Modulated Stepper Motor Valve and Fuel MixerAssembly




8.2.7 Sensors

The standard sensors for the Series 50G/60G engine are listed in Table 8-4.

Low Pressure Fuel System (Generator Set) High Pressure Fuel System (Bus and Coach)

Oil Temperature Sensor (OTS) Exhaust Temperature Sensor

Oil Pressure Sensor (OPS) Oil Pressure Sensor

Coolant Temperature Sensor (CTS) Coolant Temperature Sensor

Coolant Level Sensor (CLS) Coolant Level Sensor

Manifold Air Pressure Sensor (MAP) Manifold Air Pressure Sensor

Timing Reference Sensor (TRS) Timing Reference Sensor

Synchronous Reference Sensor (SRS) Synchronous Reference Sensor

Fuel Temperature Sensor (FTS) Fuel Temperature Sensor

Air Temperature Sensor (ATS) Air Temperature Sensor

Throttle Position Sensor (TPS) Throttle Position Sensor

Knock Sensor Knock Sensor

PSV Position Sensor PSV Position Sensor

— Oxygen Sensor

— Barometric Air Pressure Sensor (BAP)

— Fuel Pressure Sensor (FPS)

Table 8-4 Standard Sensors for Series 50G/60G Engine

8.2.7.1 Knock Sensor and Signal Noise Enhancement Filter Module

Detroit Diesel has incorporated a combustion knock protection system using a Piezo-electricKnock Sensor and a SNEF module. The system provides a signal to DDEC indicating engineknock. In the event that combustion knock occurs, DDEC will modify ignition timing. Ifcombustion knock continues after ignition timing has been modified, DDEC will begin to lean outthe A/F mixture and reduce engine power until combustion knock is eliminated.

The SNEF module is engine-mounted and grounded to the engine block via a ring terminal.Power is supplied through the OEM Sensor Power Harness. Power must be 12 VDC only andmust be sourced directly from battery or equivalent bus bar.




8.2.7.2 Fuel Temperature Sensor

The FTS sends an electrical signal to the ECM indicating fuel inlet temperature. The ECM usesthis information to calculate fuel consumption.

On Series 50G/60G engines with the Compressed Natural Gas (CNG) high pressure fuel systemthe FTS is located in the PSV (see Figure 8-11 for Models 6067–TKG8 and 6047–TKG8 andFigure 8-12 for Model 6047–MKG8).

1. Fuel Temperature Sensor 6. Air Temperature Sensor

2. PSV 7. Low Pressure Regulator

3. Fuel Mixer 8. Fuel Pressure Sensor

4. Throttle 9. Fuel Inlet Tee Fitting

5. Inlet Elbow

Figure 8-11 High Pressure Fuel System and Sensor Location for EngineModels 6067–TKG8 and 6047–TKG8




1. Low Pressure Regulator 5. Throttle

2. Fuel Temperature Sensor 6. Intake Tube Adaptor

3. PSV 7. Fuel Pressure Sensor

4. Fuel Mixer 8. Fuel Inlet Tee

Figure 8-12 High Pressure Fuel System and Sensor Location for EngineModel 6047–MKG8

8.2.7.3 Exhaust Temperature Sensor

Excessive exhaust temperature may indicate a concern with the fuel system, the ignition system,or a mechanical fault. An exhaust temperature sensor will provide early warning and preventdamage. It must be mounted in the exhaust system within 305 mm (12 in.) of the turbine outlet(see Figure 8-11). The exhaust temperature sensor does not require any sealant or antiseizecompound. The sensor pigtail must be connected to the ESH at the rear of the engine. The wiresmust be routed away from the exhaust system and kept out of contact with moving components.Refer to section 8.2.8.8 for a schematic of the ESH.




8.2.7.4 Oxygen Sensor

Air/fuel ratio is a fundamental parameter for a natural gas engine. Precise control of the air/fuelratio allows the engine to operate closer to the lean limit. As a result, exhaust emissions, fuelconsumption, and exhaust temperatures are reduced.

The oxygen sensor measures exhaust oxygen which is an indication of the air/fuel ratio(see Figure 8-13). If fuel system hardware, fuel quality, or engine operating conditions change,DDEC will sense this and make corrections to keep the air/fuel ratio on target. This is called“closed loop” control.

Figure 8-13 Oxygen Sensor




The oxygen sensor must be installed in the exhaust pipe within 305 mm (12 in.) of the turbineoutlet. The sensor has pre-applied antiseize compound on the threads. The oxygen sensor harnessmust be used to connect the sensor to the oxygen sensor interface module located at the rear ofthe engine (see Figure 8-14). The wires must be routed away from the exhaust system and keptout of contact with moving parts.

Figure 8-14 Oxygen Sensor Interface Module




8.2.8 Wiring Harnesses

The DDEC system requires several wiring harnesses for proper operation.

8.2.8.1 OEM Sensor Power Harness

This harness provides power to the SNEF module, PSV, throttle, and Oxygen Sensor InterfaceModule through a 4-pin connector. See Figure 8-15.

NOTICE:

The power supply for the SNEF module, PSV, throttle, andOxygen Sensor Interface Module must be 12 VDC to ensureproper operation and to prevent engine damage.

Figure 8-15 OEM Sensor Power Harness




8.2.8.2 Fuel Shutoff Harness

This harness connects to the engine-side fuel shutoff solenoid and provides power to the fuelshutoff valve (DDEC switch, 12/24 V). See Figure 8-16.

Figure 8-16 Fuel Shutoff Harness




8.2.8.3 OEM Sensor Ground Harness

The OEM Sensor Ground Harness provides ground to the PSV, throttle, and Oxygen SensorInterface Module. This harness connects to a pigtail on the ESH. See Figure 8-17.

Figure 8-17 OEM Sensor Ground Harness




8.2.8.4 Coil Power Harness

This harness provides power to the engine ignition coils. See Figure 8-18.

NOTICE:

The ignition coil power supply must be 12 VDC to ensure properoperation and to prevent engine damage.

Figure 8-18 Coil Power Harness




8.2.8.5 Power Harness — Dual Fuse Installation

DDC recommends a dual fuse installation. This configuration will provide redundancy on acritical circuit and prevent splicing of wire into fuse holders or power connectors. Dual fuseinstallations have two lines wired in parallel. This configuration also allows for a greater distancefrom ECM to battery. See Figure 8-19. The resistance requirement is unchanged.

Figure 8-19 Power Harness with Single ECM and Dual Fuses




Use the requirements listed in Table 8-5 to determine minimum cable gage for a dual fuseinstallation. The cable gage is based upon harness length from the battery source to the ECM.

UNITED STATES INTERNATIONAL *

Length fromECM to

Battery or BusBar (ft)

Minimum WireSize (Ga.)

TotalResistance

of MaximumLength (m )

Length fromECM to

Battery or BusBar (m)

Minimum WireSize (mm2)

TotalResistance


0 to 28 12 24.8 0 to 6 2.5 22.80

28 to 44 10 24.57 6 to 10 4 23.55

44 to 70 8 24.58 10 to 14 6 21.98

70 to 110 6 24.7 14 to 26 10 23.66

110 to 178 4 25.0 26 to 40 16 23.20

* For international wire sizes, the harness length must be recalculated to meet the resistance requirement.

Table 8-5 Power Harness Length Criteria for Dual Fuse Installations

These lengths and sizes are based on the use of stranded annealed copper not aluminum wire.Splices must be soldered and sealed with a waterproof insulator. A heat shrink — dual wall epoxyencapsulating adhesive polyolefin is required.




8.2.8.6 Power Harness — Single Fuse Installation

Single fuse installations have one line from the battery to the ECM. Single fuse installations aresimpler and less expensive than dual fuse installations. See Figure 8-20.

Figure 8-20 Power Harness with Single ECM and Single Fuse




Use the requirements listed in Table 8-6 to determine minimum cable gage for a single fuseinstallation. The cable gage is based upon harness length from the battery source to the ECM.

UNITED STATES INTERNATIONAL *

Length fromECM to

Battery or BusBar (ft)

Minimum WireSize (Ga.)

TotalResistance


Length fromECM to

Battery or BusBar (m)

Minimum WireSize (mm2)

TotalResistance


0 to 14 12 24.8 0 to 3 2.5 22.8

14 to 22 10 24.57 3 to 5 4 23.55

22 to 35 8 24.58 5 to 7 6 21.98

35 to 55 6 24.7 7 to 13 10 23.66

55 to 89 4 25.0 13 to 20 16 23.2

* For international wire sizes, the harness length must be recalculated to meet the resistance requirement.

Table 8-6 Power Harness Length Criteria for single Fuse Installations

These lengths and sizes are based on the use of stranded annealed copper not aluminum wire.Splices must be soldered and sealed with a waterproof insulator. A heat shrink — dual wall epoxyencapsulating adhesive polyolefin is required.




8.2.8.7 Power Harness Installation Guidelines

The following guidelines apply to power harness installation. See Figure 8-21 for main powersupply shutdown.

Figure 8-21 Main Power Supply Shutdown for 12 or 24 V Systems

1. Power must be sourced directly from the battery. An electrically solid connection to thebattery or bus bar is required so the battery can filter electrical noise from the power lines.Power for other vehicle systems must not be sourced from the power harness assembly.Do not use chassis ground.

2. Power and ground bus bars may be used. The bus bar must be connected to the batteryposts with 0 AWG or larger wire depending upon the total vehicle current requirement.The connecting wires must be as short as possible to minimize circuit resistance. Do notconnect the ground wire to the chassis ground.




3. Provide maximum physical separation of the power harness from other vehicle electricalsystems. Other electrical system cables should ideally be at least three feet away from thepower harness and should not be parallel to the power harness. These precautions willeliminate coupling electromagnetic energy from other systems into the power harness.

4. Use the following precautions when installing the power harness assembly:

[a] Do not route the power harness near any vehicle moving parts.

[b] Do not route the power harness assembly near exhaust system or any high heat source.

[c] Use a protective sheath and clips to prevent wires from being cut or frayed whenweaving the power harness through the frame.




8.2.8.8 Engine Sensor Harness

The following wire schematics support the ESH. See Figure 8-22 and Figure 8-23.

Figure 8-22 Engine Sensor Harness — Series 50G/60G Engine, Models6067–TKG8 and 6047–TKG8




Figure 8-23 Engine Sensor Harness — Series 50G Engine, Model 6047–MKG8




8.2.8.9 Vehicle Interface Harness

The Vehicle Interface Harness (VIH) is supplied by the vehicle manufacturer. The following wireschematic shows design requirements of the VIH. See Figure 8-24 and Figure 8-25.

Figure 8-24 Vehicle Interface Harness — Series 50G/60G Engine, Models6067–TKG8 and 6047–TKG8




Figure 8-25 Vehicle Interface Harness — Series 50G Engine, Model6047–MKG8



the natural gas engine characteristics - … · the series 50g/60g engine is spark-ignited natural...

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