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Natural Gas Conversion Systems
Transcript of Natural Gas Conversion Systems
CNG conversion systems. All of our components have been tested and approved to be
used in the United States. We understand that as engineers the best tools and
equipment are needed in order to successfully engineer a system for a specific engine.
CNG United uses proprietary electronics provided by Auto-Gaz Centrum Poland. We
have combined Polish Electronics with Injectors and Regulators provided by Auto Gas
America. We believe we have the perfect combination of components to make your
Engineering efforts seamless.
INTRODUCTION TO CNG UNITED
Natural Gas Conversion Systems
part 2 regulator
The vehicle uses several OEM sensors, such as fuel temperature, fuel pressure, coolant temperature, and manifold absolute pressure, to adjust the flow of Gasoline. Since the engine is receiving a different fuel source and the OEM sensors will still be reading the Gasoline, other sensors are necessary to help adjust the CNG fuel delivery. Our ECM uses the Gas Temperature and Gas Pressure sensors to adjust the fuel delivery. The ECM will enrich the fuel as the temperature increases in the fuel rail. This is done because the CNG will lose density as the temperature increases and vice versa when the temperature decreases. The ECM will also enrich and lean the fuel based on the pressure in the fuel rail. As the pressure increases the injection timing is decreased. A coolant temperature sensor is also used to let the system know when the optimal time is to switch to CNG.
part 5 sensor overview
The low pressure lines run from the regulator to the fuel rails. When running dual fuel rails it is
important to add two low pressure filters, one for each rail. This insures adequate flow of CNG
to the engine. The regulator has one low pressure output port. The hose connects from this
port to a "Y" or "T" fitting (for dual rail setups). After the line separation a low pressure filter
should be installed on each hose and then connected to the fuel rails. DO NOT "piggy back"
from one rail to another. This will cause uneven pressures and different flows on each bank.
part 6 low pressure lines
part 7 wiring diagrams
The best method for checking the pressure is to use the software. Set the delay to 40 seconds,
this insures the solenoids open up without the system turning on. Check your pressure once the
solenoids activate and turn the system back off. Make sure your pressure is set within the
optimal range of the injectors to start.
part 8 final inspection
Part 1 introduction
• Introduction to CNG UNITED • Components • Recommended Tools • System Information
part 2 regulator
• Regulator Diagram • Regulator Specifications • Mounting Location • Regulator Heating System
part 3 maniolds & fuel rail
• Manifolds Overview • Injection Nozzle Installation • Fuel Rail Installation
part 4 injectors
• Injectors Overview • Choosing the right injector • Mounting Locations
part 5 sensors
• Sensors Overview • Mounting Locations • Wiring
part 6 low pressure lines
• Overview • Gas Manifold Installation
part 7 wiring
• Wiring Diagrams • Injector Wiring In Depth • Solenoid Wiring • Fuel Controller
part 8 final inspection
• Pressure Checking • Wiring Inspection
part 9 software
• Software Installation • Tab Menu Overview • General Tab Functions • Configuration Settings • Auto Calibration • Map Tuning • Fuel Adjustment • Advanced Fuel Adjustment • USB Driver Information
CNG United provides the highest quality components that are affordable. Below is a list
of components that will be used when designing a system.
Pressure Relief Valve that will relieve the CNG
pressure when pressures exceed normal operating
Dual -Stage CNG Regulator
Dual-Stage Regulator Reduces the pressure of CNG from 3600 psi to 100 psi in the first stage and then to the fuel rail pressure of 20-50 psi in its second stage .
Single-Stage CNG Regulator
Single-Stage Regulator that reduces the pressure of the
CNG from 3600psi to Fuel Rail Pressure of 100-150psi
High Pressure CNG Solenoid
Shuts off the flow of CNG to the regulator when the key
is in the off position
Low Pressure CNG Solenoid
Shuts off the flow of CNG between the regulator and the
High Pressure Gauge Transducer
Optical gauge that shows the pressure of the CNG
Cylinder and transmits the pressure via signal to the ECM
Regulator Pressure Relief Valve
Low Pressure Filter
Filter for the low pressure side of the system designed to
filter out any contaminates and excessive oil. One type is
the coalescing filter and the other type is an inline
polyester filter. Both filters are 10 Micron Filters
Gaseous Fuel Rail
Gas Manifold designed to distribute the fuel to the
Gaseous Fuel Injector
Delivers a metered amount of fuel to each cylinder of
the engine. Operates the same way the OEM fuel
injectors do by opening and closing a valve using a pulse
width from the ECM
Monitors Fuel Rail Pressure and Manifold Absolute
Monitors Coolant Temperature (Regulator Temp) and
Fuel Rail Temperature for Compensations and Auto
Fuel Selector Switch
Push button switch used to toggle between fuels. Also
has a fuel level indicator LED's and Red Light out of Fuel
Activates when CNG is empty when Auto-Switch to
Gasoline is activated.
Contains all electrical inputs and outputs
CNG Injection Fuel Controller
CNG UNITED Systems are designed for the conversion of gasoline fuel injected engines only.
These systems are not "Universal" one kit fits all. These systems have to be engineered to a
specific engine. We recommend finding out as much information about the engine being
converted before any installation.
• Adjustable between 25 — 45 PSIG Pressure
• Adjustment on Top of Regulator
• Does not have Fuel Shutoff Solenoid Built onto the unit • Does not have a thermostat valve • Coolant Sensor Built into unit • High Pressure Gauge and Transducer mounted directly onto the unit
• Two Stage CNG Regulator
• Pressure Relief Valve built — On
• Rebuild diaphragm kit available
• Universal Mounting (Adjustment Screw must be accessible) • Vacuum assisted diaphragm
Coolant Heated Regulators should be mounted in the engine compartment. Non Heated
Regulators should be mounted as close to the tank as possible to ensure as much cool-down
time as possible before the gas enters the fuel rail. When choosing a location always consider
• Make sure the regulator is not touching anything other than its bracket. In some larger
displacement engines the CNG will travel at ultrasonic speeds causing unwanted
REGULATOR HEATING SYSTEM
As the high pressure gas is reduced from 3600 psi to lower pressures, the low gas loses heat
and becomes very cold. Without a regulator heating system the regulator would freeze and not
regulate the gas properly. Our regulators use the engines coolant system. The engine coolant is
routed from a delivery and return (most likely the heater core) coolant lines and into the
regulator. Since there are many different size OEM heater hoses we have included a few
fittings that may help in adapting to the regulator heating system. In some cases you may be
required to purchase your own hose adaptors to properly convert the OEM heater hose size to
the port on the regulator
It is important to know a few things before running the coolant lines:
• Make sure that two different coolant lines are tapped into which flow the coolant in
different directions. This ensures proper flow through the regulator.
• Do not re-route a coolant line using the regulator. Since the regulator has smaller
diameter orifices this could damage the engines heating and cooling systems.
manifold and injector nozzles
CNG UNITED systems use tapped port injection method of fuel delivery. When drilling and
tapping the intake manifold certain steps should always be taken.
• Always remove the intake manifold. This enables you to strategically drill and tap the
new ports as close to the OEM fuel injectors as possible without interfering with the
existing fuel system. Be careful not to drill into the same port that the Gasoline Injector
is flowing through, because this could change the spray pattern of the Gasoline.
• Make sure the intake manifold is clean and free from debris.
• Replace any gaskets that are damaged. Some intake manifolds require you to replace
the gaskets any time the manifold is removed.
• Some intake manifolds have valves or flaps before the block. Make sure there is nothing
directly in front of your new CNG port that could block or delay the injection timing.
CNG UNITED systems use fuel rail manifolds to distribute the gas evenly to the injectors. There
are several types of fuel rails, pick one that works best for the situation. Custom rail fabrication
may be necessary. Two sensors are usually attached to the fuel rails, the gas temperature
sensor, and the gas pressure sensor.
When installing the low pressure gas lines make sure the gas delivery to the fuel rails are even.
DO NOT connect one fuel rail to the other in sequence. This causes one rail to lose pressure
more quickly than the other. Each fuel rail should have its own delivery line coming from the
regulator. Teeing off the regulator is fine just make sure the low pressure filters are installed on
each rail to insure better gas flow.
Gaseous Injectors are different from normal Gasoline Injectors. We have several different types of injectors.
solenoid type injector that uses the fuel rail as a stop for the valve. Its valve mechanism uses a magnet and a spring to meter the amount of gas flow. This type of injector has a slower response time and is not recommended for newer vehicles with fast OEM injectors. These injectors also require maintenance every 20-30K Miles. These injectors come with one flow type. The horse power or flow is adjusted using different nozzle sizes. The smaller the nozzle hole, the lower the gas flow. General operating pressures range from 1.2-1.8 bar.
This technology was patented by an Italian company. These injectors are similar to the Solenoid Valtek because they utilize the block as part of the metering. These have a magnet that pulls a metal sleeve down on one side and opening the gas port on the other. These operate much like a teeter totter. These injectors are very fast due to the short distance needed for the sleeve to flip open the gas port. Most Matrix injectors can handle very low injector open and close times. General operating pressures range from 1.2 to 1.8 bar.
PEAK AND HOLD
These injectors are also considered Solenoid Type Injectors most peak and hold injectors are low impedance that requires a peak amp current and a lower hold amp current to operate them. It uses a higher current to open the injector and a lower current to hold the injector open. These injectors come in many different sizes and flows so check the Injector flow chart to match them. This injector operates the same as most Gasoline Peak and Hold Injectors with a pintle or needle that moves up and down by electromagnetism. General operating pressures range from 1.2 to 3 bar and Some even as high as 150psi.
CHOOSING THE RIGHT INJECTOR
Selecting the right injectors are probably the most important part of the conversion process
This could help eliminate hours of troubleshooting only to find out the wrong injector sizes
were selected for the project. Make sure before selecting the type of injector you know the
• Match the horse power of the engine to the injectors
• Make sure if the OEM engine uses micro-injection that the Gaseous injectors are fast
• Make sure the injector driver has the proper voltage and amps to drive the chosen
• The offset (the difference between the OEM pulse width and the Gaseous Injector pulse
width) should be at least a positive 1.0. Any lower than this and the OEM pulse width
could end up pulsing below the range of the Gaseous Injector.
• All of the injector hose lengths need to be the same size. This ensures that each injector
will match the flow of gas going into the engine.
• The shorter the injector hose length the better. Shorter hose lengths mean that the gas
has less distance to travel when entering the intake manifold. This ensures quicker
engine response time.
Coolant Temp. Sensor This sensor should be mounted near the regulator to accurately monitor the temperature of the engine coolant at the regulator Fuel Temp Sensor This sensor should be mounted on the fuel rail. The fuel rail will give the most accurate reading of the temperature of the gas - before it enters the combustion chamber. Some of our custom fuel rails do not have the port for this sensor to connect. In that case you will be required to drill and tap your own port on the fuel rail plug.
Fuel Pressure and MAP The MAP sensor and the fuel pressure sensor are integrated into one. This sensor should always be mounted with the barbs facing downward and away from the engine to stay cooler. This component can be mounted in the engine compartment but needs to be on the side if possible.
There is a blue wire from the new ECM Wire Harness that sends a Positive (+) signal when the
Solenoids are activated. This wire is meant for only one Solenoid. If multiple Solenoids are
required, a relay must be placed in the circuit. The Blue wire then activates the relay connecting
direct (Higher Amperage) to the Solenoids of the system. A Diagram is shown below.
The Fuel Controller is simple to wire, just plug in the harnesses. One thing that is imperative to
successful installation is to mount the ECM in a low temperature location. If the ECM must be
placed in the engine compartment, make sure it is as far away from the engine as possible and
shielded from high temperature air flow. It is always recommended to install the ECM under
the dash on the other side of the firewall. Also make sure it is mounted firm,and does not have
any play. The ECM has sensitive drivers and other components that can be dislodged from
part 9 software
1. CNG Inlet Port (Filter Cartridge Shown) 9/16”-18 UNF SAE Port
2. Pressure Sensor Adaptor
3. Coolant Inlet/Outlet Ports
4. Pressure Relief Outlet (Valve) Port (5/8 Hose)
5. Mount – Bosses 5/16’-18 UNF-2B
6. CNG Regulated Outlet Post ¾” – 16 UN-2B
7. HP Solenoid Valve (Hp Gas On/Off)
pressure relief device
• Never mount the regulator behind the wheel where rocks are likely to strike
• The regulator should always be mounted in a protected area free from rock hazards,
dirt, salt and any other non-protected areas.
• Before mounting the regulator, make sure the locations of all the coolant and fuel hoses
are planned before hand.
• Make sure the chosen a location is easily assessable because some minor adjustments
to the pressure may be necessary.
• Rated horse power of the engine
• Minimum Pulse of the OEM Injectors
• Maximum Pulse of the OEM Injectors
Once as much information is obtained about the engine being converted, select the proper
injector. Most of the time the injector is selected by horse power rating. Each Injector has a
maximum horse power rating per injector. This horse power rating is directly relative to the
pressure of the gas. The Injector Specifications Section will help when selecting what injectors
will work the best for the engine. A few things to look at when selecting the correct size are as
• Type of OEM Injector such as Micro-Injector, Low Impedance, High Impedance. This
matters to know how the injection timing will differ between the OEM and the new
When mounting injectors make sure it is planned well. Find a place on the engine that is close
enough that the hoses to the manifold are no more than 8 Inches for Solenoid Injectors and 3
Inches for Peak and Hold Injectors. Also consider the fact that the injectors need to be mounted
with rubber dampeners. Solenoid injectors can be very loud if they are mounted metal to
metal. A few things to consider when mounting the injectors are as follows:
Fuel pressure sensor
CNG Powerstroke Low pressure fuel hose
Injector Wiring in Depth
Since our Fuel Controller takes the injector pulse signal from the factory ECM and intercepts it
for cutting power to the Gasoline Injectors, Splicing into the injector pulse (-) wire is necessary.
Once the Gasoline Injectors are turned off, the Fuel Controller takes that signal, modifies it, and
then sends the modified signal to the new Gaseous Injectors. It is imperative that the proper
wires are intercepted as to not damage the OEM and NEW Injector Drivers. Some Engineers
prefer tapping into the Common (+) wire of the injectors as a good key-on source, this is ok.
When intercepting the injectors, the firing order is not important. To ensure the proper injector
fires at the correct time you must match up the Injector signal wire color on both the OEM
Injector interception wire, and the new Gaseous Fuel Injector.
Before plugging in the ECM it is always recommended to inspect your wiring thoroughly. It is
always safer to inspect the wiring before attempting to start the system rather than running
into problems later and possibly damaging the equipment. Eighty Percent (80%) of all support
calls are wiring related issues. NO ONE is exempt from wiring something wrong. After you have
inspected your wiring, plug in the ECM and run the software. Once all your settings are
selected, start your engine check the following readings.
• Coolant Temperature
• Gas Temperature
• Manifold Pressure
• Gas Pressure
• RPM Signal is accurate
• Check each injector for an accurate pulse. If you have a single injector with a pulse that
is out of normal range compared to the others, injector wiring must be checked.
Check out our
Zenit Pro Software Manual