At the time of writing, regular unleaded gasoline average Canadian prices hit a new and grotesque milestone of over $2 per litre. And as expected, pop-up and spam ads for fuel-saving devices are appearing faster than dandelions on suburban lawns. With every fuel price surge, a new batch of products claiming 20+% improved gas mileage tries to capitalize on our commuting grief and need to save some money. The latest fad really isn’t new: plug-in engine control chips.
Performance addicts, off-roaders, and modified truck owners have been using engine control software plug-ins for years to improve power, accommodate non-stock tire sizes, and increase top speeds. And while the effects of most of these products are measurable, so are the risks.
The chips, proms, or plug-ins we’re talking about are the ones that insert into the industry-standardized diagnostic connector under the left side of the dash of pretty much every vehicle on the road. They basically come in two formats: ones that permanently rewrite the factory drivetrain control software, and ones that provide only a temporary patch that’s undone when the plug-in is removed. In theory, these types of add-ons have the best chance of actually improving fuel mileage if you don’t mind risking factory warranty coverage or engine longevity.
It would be easy for a programmer to alter fuel injection rates and ignition timing to get more out of a litre of fuel. There would likely be a minor drop in peak horsepower and torque, and even a slight increase in engine operating temperature. Over time, a modification like this is certainly able to save you money, but at what risk? How would the reliability of the engine be affected? Would any emission control components see damage or shortened life-spans? And what about factory warranty?
While an owner might remove their plug-in device before taking the vehicle into the dealership for some warranty repairs, its activities can leave a trace of their operation in the onboard computer memory that can be retrieved by a technician. If that warranty repair involves anything connected to the engine control system, the manufacturer may deny coverage. Just like most of the aftermarket fuel economy improvement offerings of the past, there are more unanswered questions than useable information in their pitches.
Let’s leave you with this question: if these products are really that effective and safe to use, why aren’t all major vehicle fleets using them and why aren’t automakers providing their software benefits right from the factory?