Injected Kits

So if you have made it this far you are more than likely getting the itch to convert. Smile Good for you and I hope I can offer the necessary information you are looking for to get it done and with the right equipment for you. Lets get started.

 CNG ECU – Compressed Natural Gas Electronic Control Unit. Its the fancy technical term for the new cng computer.

MAP Sensor - Mass Air flow and Pressure sensor. Your vehicle already has one for the petrol/gasoline system and the cng systems uses its own to run more efficiently.

Fuel Rail – Solid rail that holds the CNG Injectors, or it simply divides up the low pressure fuel into individual low pressure fuel lines to the injectors.

Injector port - Access point at where the fuel is injected into the intake manifold above the cylinder head.

How does this system operate?

Obviously this kit is injected like the name states however it isn’t a true injection system as we think of  like our regular vehicles petrol/gasoline injection system. The difference is that your current vehicle’s petrol/gasoline injectors inject directly into the piston cylinder or directly above and are strategically located to maximize the fuel injection into the cylinder. The natural gas injection system attempts to inject CNG as close to the cylinder as possible by drilling, tapping, and installing new injection ports and holes slightly above the current injectors or as close as can be possible given the other equipment surrounding cylinder head, unless it is a factory system like a Honda or a Chev/ford/dodge fleet vehicle which are traditional injection systems that we are familiar with. These new injector ports that have just been installed are supplied with CNG from an injection rail(s) depending on your number of cylinders, that fire in the same order as your current injectors by borrowing the signal from your existing injector and relaying it to the new injector for its appropriate cylinder. It only injects the amount needed for that cylinder.

The injector rail recieves the fuel from a low pressure fuel hose that is supplied from the regulator. Some times there are low pressure filters inline before the injector rail to remove any debris from the regulator or compressor oil that inadvertantly gets into the fuel. The regulator recieves the natural gas from a high pressure fuel line that comes from your high pressure cng tank. The regulator works to reduce the high pressure fuel to a working pressure for the system and like the aspirated kits also has coolant lines that keep it at an operating temperature and prevents it from freezing as the natural gas depressurizes.

The coolant lines are tapped into the heater hoses and simply run in and out of the regulator.

Unlike most aspirated systems the injected systems will use a their own MAP sensor to help regulate the amount of CNG released into the system. The map sensor takes a combination of inputs from the vacuum off the intake manifold and regulator to a pressure source off the fuel rail. It then feeds this information back to the CNG ECU and provides it with immediate feedback for better response to any and driving conditions.

Another difference from the aspirated systems is that the injection systems usually take a temperature from a couple points in the system to help keep the system operating smoothly. This input is used as a signal to when the CNG turns on if you choose to allow the system to do it automatically. Once it reaches the correct operating temp it will switch over on its own if the change over switch is on.

Change over switch. This will be located in the cab of the vehicle and will provide a display for what fuel the vehicle is operating on and what the current pressure of the high pressure tanks are at for a fuel gauge. It can be toggled between fuels without damage to the motor at any time.

The hardware for the system

  • High pressure fuel lines that feed into the pressure regulator/s. These supply the CNG to the regulators from tank/s.
  • Regulator. Reduces the compressed natural gas to a working pressure for the injectors.
  • Low pressure fuel lines. Takes the now decompressed fuel lines at the lower working pressure and feeds to the injector rail and from the injector to the injector port.
  • Coolant lines. There are coolant lines that are connected through the heater hoses to the regulator. These provide coolant to the regulator and heat up the natural gas. This is required because of the heat loss that occurs from the fuel decompressing. These coolant lines prevent the regulator from freezing and maintaining a working temperature in the regulator.
  • MAP sensor and vacuum lines. As mentioned above this takes a vacuum signal from the intake manifold as well as a vacuum signal from the regulator and a pressure signal from the fuel rail and transmits it to the CNG ECU for better response to current driving conditions.
  • Temperature senor. There will be a couple of points where a working temperature is taken for smooth operation. One is usually taken off of the regulator and the other off of the fuel rail.
  • Pressure Gauge. This can be mounted in line with the high pressure tubing or mounted to the regulator. This will provide information for the fuel gauge inside the cab on the change over switch.
  • Mounting hardware and fittings. The kits should come with the basic supplies to mount the hardware and keep the electrical lines out of moving parts. Be sure to secure all the equipment.

Things to Consider, Tips and Tricks

  • On any type of a system before you commit to installing a CNG system, carefully look it over under your hood and look for where you will put what. If you map it out in advance you will save a lot of time guessing later.
  • When you are installing your injection ports evaluate a location that will be approximately the same distance for all injection ports to the cylinder. You don’t want to have 2 or your 4 injection ports right next to the cylinder and 2 of them a few inches away because it won’t operate as smoothly as it should. Place them all relatively in the same spot per cylinder. If it is a few inches further than you would like but it gives you the necessary room to drill and tap it then it will be fine.
  • If you are working with an intake manifold that is plastic or a polymer then you can probably drill and tap it in place if you have the room. Drill slowly and remove all the shaving with a vacuum or by hand. When you tap it place some grease or vaseline on the tap to collect the plastic shavings.
  • If it is a metal intake manifold you will need to remove it for installing the injection ports. Be sure to mark it so you don’t drill it and install the ports only to realize there will be something in the way after you reinstall it.
  • When you are installing the new injection ports, press some of the low pressure tubing onto the new port and use the hose to thread it into the new hole. This will  give you more room to hold it and hopefully prevent you from dropping it down somewhere you don’t want to accidental. Place some loctite medium strength on the threads as well just to help seal the fitting in place.
  • Make sure all loose wires, connections, tubing are tied up in a secure location. Keep them secured and away from moving parts.
  • A tip for regions or areas with emissions. If you live in an area with emissions testing and you install or have a CNG system installed on your vehicle it will likely fail the emissions test because it isn’t really an emissions test.Surprised Its really a scam!  They are simply plugging into your OBDII and checking for any codes to see that your vehicle is operating without any error codes, instead of actually pulling the particulate count from your exhaust. (They do this but it isn’t decided by the counts your vehicle puts out.) Since the CNG system will more than likely cause the lean error code to go off it will fail the test with that code. The way around this is simply by purchasing an OBD scan tool from your local auto parts store (the cheap one that can clear codes). Clear the code and drive on regular gas for at least 50 miles before having the emissions tested. Leave it on regular gas until you pass the test then switch it back over to CNG. (it sounds silly to burn a dirtier fuel and pollute more in order to pass the test but that’s is what you have to do.) The reason for this is because they need to have a history in the cars ECU to reference if it is operating correctly and clearing the codes immediately before going won’t give them the history they need.
  • After you are done with the installation and getting ready to tune the system make sure the instructions tell you what the working pressure should be. It took me several hours on a vehicle the first time i was trying to tune an injected system because it didn’t contain that information. I am referring to the low pressure fuel line and its specific working pressure. When you are plugged in to the system with your laptop, it should have a pressure to the injectors, this is your working pressure. I finally contacted the supplier of the kit i bought and he mentioned to me that the pressure should be around 2.1 bar. So when i plugged in it was reading a static pressure of 2.05 and i thought it would be sufficient but after starting the truck it wasn’t because when the injectors began working it would drop pressure to approximately 1.3 bar and the system was effectively starving for fuel. I had to make the necessary adjustments on the regulator to provide a continuous working pressure of 2.13 bar for it to run properly. That information wasn’t given to me and I had to figure it out. Every system will be slightly different but that will hopefully prevent any lost time for you.


High pressure tubing and fittings. After you have mounted your regulator and tank you will need to link it to a fill nozzle and the regulator. When you are attempting to plumb the system you need to spend the time to get the angles correct with the tubing. The more time you spend with lining up the tubing to where it will be connected the first time the more time you will save yourself from leaks.

  • Tip one – If you are using the 6mm zinc plated tubing. check to see how soft the plastic covering is. If it is hard or brittle, send it back and request some newer tubing. It isn’t worth the time you will spend trying to keep it from leaking.
  • Tip two – Do not use pliers, of any sort to attempt to bend your tubing to line it up. Using them will create a flat spot in the tubing that will be very difficult to seal. Use your fingers. Give yourself at least 2 inches of a straight shot into the fitting to line it up. Make sure it lines itself up without any external force required. Spend the time and line it up correctly, it will save hours of time trying to fix the leak you will cause if you don’t line it up. I will try to post a video of this later but again get it lined up perfectly without any external pressure and don’t use pliers or a tool to straighten it. You will only be causing yourself more of a headache.