I’m a certified Automotive Technician and fuel saving inventor; so I was in a unique position to understand WHY the EFIE was needed when electronic fuel injection systems started using oxygen sensors in the 70’s and 80’s.
Effective combustion enhancement (fuel saving) results in more than ‘normal’ oxygen levels in the exhaust (see EFIE literature for why this is). The vehicle’s computer woul then recieve a lower voltage from the oxygen sensor and would ADD FUEL to compensate (negating the potential fuel savings).
I did experimentation and discovered what needed to be done to ‘correct’ the voltage output of the oxygen sensor so that the computer wouldn’t add additional fuel. I got several quotes from electronics engineers to build the circuit I desired and the LEAST cost one was $30,000. I decided to learn electronics and do it myself, which I did. Again, as an Automotive Technician and inventor I was in a perfect position to KNOW what was needed.
I developed the EFIE to have a ‘floating’ voltage. This is a voltage that is NOT connected to vehicle ground. A floating voltage allows you to add an (user adjustable) voltage to the oxygen sensor’s voltage WITHOUT any possibility of damage to the vehicle’s computer. This can ONLY be done using a transformer, because a transformer decouples the source of the voltage from ground. Thus my EFIEs are ‘digital’ to generate the original voltage but analogue (with transformer) to connect it to the vehicle.
Once the need for the EFIE became well developed, other electronics designers came up with their own circuits to add voltage to the oxygen sensor output. They did NOT use a transformer so do not have a floating voltage. They advertise their circuits as ‘digital’ like it’s an advantage. It’s not!
My circuit allows the ORIGINAL oxygen sensor voltage to go to the vehicle’s CPU, adding a (variable) voltage.
Their circuits stop the original signal from the oxygen sensor, using it as a reference to generate a ‘new’ signal to the computer.
The two problems with this ‘non-floating’ technique are both related to the vehicle’s ground. First, if there is ANY ground issues with the ‘digital’ EFIE or the oxygen sensor, the ‘digital’ EFIE will not function correctly. Second, the ‘newly generated’ signal may be incompatible with the vehicle’s computer, with possibility of damage to the computer.
I’ve improved the EFIE in the decades since I first invented it and I still use the floating voltage because I design to be SURE of no damage AND reliably achieving the goal.
Further you may hear of how my EFIE increases voltage as it warms up, like it’s a bad thing. I DESIGNED the EFIE so that it would not lean the mixture too much when the engine is cold, and gradually lean more as it warms up, to achieve maximum savings with no performance issues.