With motor fuel prices higher than an upset cat’s back, who wouldn’t want to increase their fuel economy? Recently a slew of articles have appeared in legitimate media for little devices that plug into your vehicle’s OBD2 port. They make comforting promises: “Lower your car’s fuel consumption up to 45% with this amazing device.” [fuelfixpro] “EcoOBD2 adjusts itself to the vehicle, according to the driver’s habits and always maintains the remapping ECU to save fuel and reduce discharge.” “EcoOBD2 Saves 15% fuel for Benzine cars.” Drop your consumption by 45%? Are these fuel savings for real?
“One size fits all”?
How do these “fuel-saving devices” work? The typical advertisement says something like this one, from EcoMaxFuel: “Every modern car made after the year of 1996 has an ECU (Electronic Control Unit). This is the car’s brain, and it monitors the performance and optimization of the engine. Once installed and you’ve driven around 150 miles with the EcoBox Fuel Saver connected, it will have enough data to begin tuning your car’s computer for lower fuel consumption.”
RV diesel rig owners have been using electronic chip technology to help them develop more engine power for years. But no matter what engine you have, you can’t just buy a “generic” chip and plug it into your rig. Each chip is specifically designed for the rig, year, and model. Engineers analyze how each vehicle’s computer operates, and “map” a variety of parameters to make it all work. With all this work, it’s no surprise you’ll spend a few hundred bucks for an aftermarket chip. It’s not some sort of “one size fits all” affair.
Video reveals the truth
With that in mind, it’s reasonable to ask: How can somebody reprogram an ECU with a fuel-saving device that sells for anywhere from less than $10 to up to $70? And how can these fancy fuel-saving devices do “one size fits all” for literally hundreds of different vehicles? The simple answer is—they can’t.
So, just what are you getting if you buy one of these little plug-ins? Put simply—a little plastic box with a blinking light. We found an exposé YouTube video that shows just what you get. David Jones, an Australian engineer with a Type A personality, has been cranking out weekly YouTube casts under his EEVblog. Jones says he has a 25-year history in electronics design.
What’s really under the hood
Jones took the cover off an “ECO OBD2” fuel-saver device to figure out exactly what it does—or doesn’t—do. If you have a few minutes, we recommend you watch the video for the more technical details. We’ll break it down to the simplistic.
What’s inside? A circuit board, some light emitting diodes (LEDs) and an integrated circuit device. Just what kind of integrated circuit it is, couldn’t be told. Jones discovered that the identification numbers that would show just what the device is had been cleverly scrubbed off. There’s also a “reset” button, which the instruction set prompts you to push on installing. Oddly, the instructions don’t tell you where to find it.
On his test bench, Jones applied power to the appropriate connectors to simulate the device being plugged into a vehicle’s OBD2 port. With the cover off, three different LEDs began to flash in a particular sequence. Interestingly, the customer will only see ONE of these lights—the other two are under the opaque plastic cover. If the light you see flashing is indicating the “fuel saver” has made a connection with the vehicle’s ECM, think again. The LEDs flash in sequence when the power is applied—without even being attached to an OBD port.
“Reprogramming” signal won’t ever get to your engine computer
A closer examination reveals that any reprogramming signal that this device could send out to the ECM would never get there. Two resistors of such a high value are plumbed into the leads that reach out to the ECM. These effectively squelch any signal that might be sent. Further, about half the pins of the integrated circuit aren’t even connected to the circuit board itself. A major tipoff that “something is rotten in Denmark.”
When Jones connected the fuel saver to a live OBD2 port, the findings showed more baloney. With the device plugged in the port, the LEDs sequenced exactly the same, regardless of whether the engine was off, in “key on” position, or actually running.
Here’s the bottom line. The device does NOTHING to communicate with a vehicle’s ECM, and so can do NOTHING to alter fuel efficiency. Jones’ bench test did reveal that the ECO OBD2 device did do one thing for a vehicle: Draw power. Anytime the box is plugged into the OBD2 port it draws 50 milliamps, “draining a 40-amp-hour battery in a month,” concludes Jones.
Sucker born every minute. Don’t be one
No matter how much money you spend, you’ll not be saving a cent in fuel costs. Like Barnum said about a sucker born every minute. There are plenty of outfits that want to take your money. Articles about how “great” these devices are for fuel saving have appeared around the country in legitimate newspapers. They look like genuine news articles. It’s only when you reach the bottom of the story do you read that these aren’t true reviews, but paid advertisements. On Amazon.com, there are about a dozen or so of these “fuel savers” luring customers with siren songs of increased fuel economy, boosted power, etc.
Want to save money? Keep your tires properly inflated. “Keep your foot out of the pot,” meaning, slow down, and don’t do jackrabbit starts. Just these two tricks alone are GUARANTEED to save you more fuel than any of these plug-in “miracles.”
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