Handling Your Vehicle's Electronics To Work With HHO


Back in the "good old days", you had carburetors and distributors, and no one ever heard of putting a computer in a car. If you wanted to modify the engine, and in particular, if you wanted to add supplemental hydrogen, well you just did it. The results were instantaneous, and there was no computer to get in the way. Even today, diesels are still in much the same state. Add an HHO generator, and you're done. You can start getting instant mileage increases without further fuss.

With the coming of modern fuel injected vehicles, there is no longer a carburetor mechanically metering out the correct amount of gas to the engine. So an array of sensors is needed to monitor what is going on with the engine, and a computer to calculate the correct amount of gas to inject. This all started out pretty simple in the beginning, but as the computer chips became more powerful, the programs started getting more complicated. However, in the end, you have a few sensors being used, and with the data from these sensors, the computer is calculating the amount of fuel to inject to make the engine run properly.

I've been finding a lot of people are confused on the subject of these electronics. I've even talked to a growing number of cell designers & resellers that only want to deal with diesel engines so they won't have to tackle the computers of gas burning cars. I've heard people say that cars built after 2004 won't get better mileage with HHO because the computers won't allow it. All of these observations make it clear that there are some confusions on the subject of the car's electronics, and we had better get this subject better understood so we can all be more successful using HHO.

The Basics

In order to get good results with an HHO system, you have to do 2 things: 1) Get a good, efficient source of HHO, and get it into the engine, and 2) Handle the computer so that it can accept the resulting improved combustion. That's all. That's the simplicity of what we are trying to do. If we achieve those 2 things, we will get a remarkable increase in fuel economy, and a dramatic decrease in vehicle emissions. This article assumes that you have a good HHO supply for your engine, and will strictly cover handling the sensors and the computer.

As is covered in more depth in other articles, when using HHO (or any other technology that causes more efficient burning of the petroleum fuel), one of the phenomena that occurs is that there is more oxygen appearing in the exhaust (see Oxygen Sensor Adjustment - General Information for more information). When this information is fed to the computer from the oxygen sensors, the computer reacts by adding more gas. However, in this case, the added gas is more than the engine needs. The reason the computer is adding fuel is that the oxygen levels in the exhaust are telling it (incorrectly) that the air/fuel mixture is too lean. The trouble is, the mix was correct, and the fact that the fuel is being burned completely is fooling the computer into thinking that the mix is too lean. It just wasn't programmed for combustion to be this complete. This is the factor that we have to overcome in order to get our results with our HHO system.

Sensors, Sensors and More Sensors

Computers use a number of sensors to figure out the air fuel ratio, and thereby the amount of fuel to deliver to the engine. Chief among these is the oxygen sensor. But also used are the MAF (Mass Air Flow) sensor, the TPS (throttle position sensor), the MAP (Manifold Absolute Pressure) sensor, IAT, CTS (Intake Air and Coolant Temp Sensors), and RPM Sensor. This is not a huge list of sensors, and all vehicles use a combination of these sensors to do the calcs for amount of gas to deliver. Further, while there are a few variations of how each sensor does its job, the basic information they give is the same for all cars. For instance, there are wide band oxygen sensors and narrow band oxygen sensors. They operate completely differently, but they still both tell the computer the same thing. The same goes with the rest of the sensors. They all tell the computer the same information. Even the computers themselves are pretty much doing the same thing. The only real variation from vehicle to vehicle is the programming of the computer.

The programming can vary widely. And its this fact that makes the job of getting the computer to accept the HHO most challenging. I don't point this out to make the task look daunting, I'm only trying to point out what the task actually is. Once we can see what we have to do we can confront it and handle it in an orderly manner. It also helps to know that one size does not fit all when it comes to the task of handling the vehicle's electronics. But they can all be done.

Oxygen Sensors

We always start out by adjusting the oxygen sensor's data. We use an EFIE for this (Electronic Fuel Injection Enhancer). There are many articles on my site about these devices, and if you want more information on them, please see our Documents Page. But the point is, by adjusting the information coming from the oxygen sensors, in most cases, the vehicle will be solved. In the past, we have usually treated only those oxygen sensors that are upstream of the catalytic converter. However, when that isn't enough, there are plenty of other steps that can be taken to solve the problem.

Before proceeding with further recommendations and remedial actions, I'm going to assume you have already gone through our HHO System Debug Checklist. The most common reasons an HHO system is not working are simple errors that can be caught by going through this list. It has the common errors that we have turned up on our tech support lines, trying to help people get results with their systems. If points on the checklist are out for your vehicle, then adding further sensor handlings will not solve the project. Actually the things I will cover here are in the checklist, but at the very end. The idea is to solve the common and easily solved problems first before diving in to the more esoteric and expensive sensor handlings.

Downstream Oxygen Sensors

With that said, after installing EFIEs on all upstream sensors, if I still haven't reached my mileage goal, I will look at the downstream sensors. Traditionally we have always "known" that only the upstream sensors need to be treated with an EFIE, because the downstream sensors aren't used in the air/fuel ratio calculations. Usually these downstream sensors are only used to monitor the health and efficiency of the catalytic converter. However, we have been finding more and more vehicles that do use the downstream sensors in their air/fuel calculations. A number of manufacturers document this usage. These include Chrysler/Dodge, Honda, and Jeep.

There are other manufacturers that don't document this usage of downstream sensors, yet still have been found to be using them. Notable among these is the Ford F Series pickups. We've solved a number of projects by treating the downstream sensors on these trucks. We've also found vehicles from other manufacturers that throw codes if the downstream sensors are not treated. So even though they aren't using the downstream sensors for the calculations, they are still checking the upstream sensors, and can invalidate their use if the readings don't agree. In these cases we must also treat the downstream sensors.

To make it economical to treat 2 upstream and 2 downstream sensors on a V-6 or V-8 engine, we created the Quad Digital EFIE. It has 2 digital EFIEs for the upstream sensors, and 2 analog EFIEs for the downstream sensors. With this device, you can handle all of the oxygen sensors on your vehicle, and don't have to worry about whether the downstream sensors are causing a problem for you. I now use the Quad Digital EFIE on all new vehicles with narrow band oxygen sensors, because it never hurts to treat the downstream sensors, and more often than not, will avoid "mysterious" problems later.

Other Sensors

By this point, most vehicles are done. They will be getting 30%-50% mileage improvement (or better) and that's about what you should expect from an HHO system. But if you are still below 25% mileage improvement, and you have done the steps of the HHO System Debug Checklist, you may need to treat other sensors as well.

The MAP or the MAF will be the next sensor to address. Most vehicles have one or the other of these 2 sensors, but not both. If you do have both, you'll have to experiment to find out which one works best. I always start with the MAF in these cases, but some vehicles get better results treating the MAP. In any case, the same handling works on both devices. A Simple MAF/MAP Enhancer covers how to make your own MAF/MAP enhancer for a few dollars. A slightly more advanced circuit can be found in Tuning For Mileage. These handlings only work with sensors that put out a simple voltage type signal to the computer. There are MAF and MAP sensors that put out a frequency signal, and currently no devices are available that work for these types. However, we are currently prototyping a universal MAF/MAP enhancer that will work on all types of sensor, including the frequency types, and this device is now available in our online store by Nov, 2009.

The last sensors to address are the temp sensors. You'll probably have both of these, and they are the CTS and the IAT sensors. I have never adjusted these on my cars, but if I were not getting my results by doing the above sensor handlings, I would then adjust my temp sensors. You can do these with a resistor, but I would use a pot. That way the adjustment can be find tuned. I would also try to use an OBD2 reader while I was setting these so I could see the result. You want to end up with a setting that will make the temperature about 10 degrees hotter. The details of how to modify your temperature sensors can be found in the article Tuning For Mileage.


There is no reason, today, not to get great gas mileage. You should be getting from 30%-50% improvement. All you need to do is:

1. Provide a good source of HHO to your intake

2. Handle the electronics so they are not nullifying the improved combustion performance you now have.

That's all it takes.

With all the modern electrolyzers that are being made today, there's no problem getting a good source of HHO. The electronics part can be a little tricky for a person dealing with them for the first time, but handling them is usually also very straightforward. Your best solution is to purchase an EFIE from FuelSaver-MPG, and follow the installation instructions exactly. We recommend our Documents Page very highly for further information about how to go about all of this, and to understand some of the underlying principals. But realize that you are only trying to achieve the 2 steps described above. Get these done, and you'll have the mileage you have been hoping for.

Good Luck!

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