Dealing with Oxygen Sensor in Fuel Injected Vehicles

Most modern-day fuel injected vehicles use a computer and oxygen sensing devices to monitor and maintain the correct oxygen/fuel ratio. One of the key sensing devices is the oxygen sensor or called exhaust sensor. Fuel injected vehicles have one or more oxygen sensors installed in them. The computer extrapolates what the air/fuel ratio is based on the amount of oxygen in the exhaust, as reported by the oxygen sensor.

The computer in a vehicle is also called the Electronic Control Unit (ECU). It controls the fuel injection system, ignition timing, and the idle speed control system. The ECU also interrupts the operation of the air conditioning and EGR systems, and controls power to the fuel pump (through the control relay). The ECU consists of an 8-bit microprocessor, random access memory (RAM), read only memory (ROM), and an input/output interface.

When a fuel saving device is installed, such as an oxy hydrogen generator, the petroleum based fuel is burned more completely. One of the results of this is that there is more oxygen (and less unburned hydrocarbons) in the exhaust stream. This is a good thing, and is in fact, what we are trying to achieve. However, the computer will perceive this condition as a “too lean” air/fuel mix. In other words, what is now a desirable condition in the exhaust, will be interpreted as “not enough fuel”, and the computer will direct the fuel injectors to increase the amount of fuel being pumped into the engine.

The result is that the oxygen sensor and computer prevent efficient combustion from occurring! In other words, it cancels out most of the improvement we have just made.

The Solution

The oxygen sensor “tells” the computer what the oxygen content is by providing a voltage on it’s signal wire between 0 and 1 volt. 450 millivolts (.45 volts) means that the fuel/air mixture is correct. Higher values means the mix is rich (has too much gas), and lower voltages means the mix is lean. By adding voltage to the sensor’s output, we can compensate for the additional oxygen in the exhaust.

The Electronic Fuel Injection Enhancer (EFIE), (not MAP - Manifold Absolute Presure - Sensor Enhancer), does exactly this. It adds a floating voltage to the top of whatever the oxygen sensor is putting out. It has an adjustment that allows you to control, to within a few millivolts, the amount of this added voltage. This allows the computer to be unaware of the additional oxygen content of the exhaust, and the oxy hydrogen generator can now achieve it’s full potential in fuel savings.

Most cars have oxygen sensors both before and after the catalytic converter. The ones downstream from the converter do not need to be treated. Their data is used to determine when the converter has gone bad, but are not used in the air/fuel calculations. EFIEs are only needed for all upstream oxygen sensors.

If you are purchasing an oxy hydrogen generator for a fuel injected vehicle, click here to check these commercial available electronic fuel injection enhancer products.

We do not plan to implement this EFIE device in the initial testing stage on our Dodge Sprinter as we’d like to see how much it saves fuel without using the device - I was told that an EFIE does not help much with fuel saving for Dodge Sprinter as its oxygen sensor is a wide band sensor.

Note that Hydroxy Tech offers a device called VMU (vehicle management unit) in their complete HHO generator kits to deal with oxygen sensor, MAP sensor and MAF sensor.

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