This is an updated version of an article I wrote three years ago, this time testing a new device/app combination in a gas-powered Class A motorhome.

Confession:  I am a data junkie.  Yes, all scientists are data junkies, but my particular dependency is much worse.  I have a smartwatch that monitors every step I take, every flight of stairs I climb, and every heartbeat; my bicycle has a mounted computer that provides me with every bit of information about how fast and far I’m going; and there have been many other gadgets – smartphone, tablet, computer – to keep a stream of email and messages and news flowing to my brain.  It is ridiculous, I know, but like any junkie, I can’t help myself. 

Our Tiffin Class A motorhome (2017 Allegro Open Road 32SA) is yet another gadget that feeds me a constant stream of data about road speed, engine rpm, fuel level, fluid temperatures, distance traveled, and my location on a colorful map.  Why is that not enough?  Because when I’m driving the motorhome, I am always making mental comparisons to driving my car.  That 11-ton motorhome is nearly 6 times the weight of my car, but the RV’s engine does not have even twice the horsepower or torque of my car’s engine. So it’s no surprise that the motorhome engine is clearly working harder, especially during acceleration, on grades, and at freeway speeds. 

And that started me asking myself:  If the engine is working harder, what is the long-term wear-and-tear on the engine components?  How much does our overall weight and engine load affect fuel economy?  Should I be driving differently to reduce the strain on the engine and improve its efficiency?  How is the engine affected by running the air conditioner, by driving up a mountain pass, or by extremes in outdoor temperatures?  The answers depend on gathering more data, especially since there is a lot of performance information that is not displayed on my motorhome dashboard.

That’s when I decided to get a device to monitor the parameters revealing how well and how hard the engine is working.  The information can be collected from a vehicle’s standard OBD-II port, which is the connection used by service technicians to access diagnostic data from all the onboard computers.  Since these data are also accessible while you’re driving, the trick is to choose the best data to display in a way that is instantly informative rather than distracting.

I already have a bright, colorful graphic interface ready to show this powertrain information:  my iPhone X is always mounted just to the left of my steering wheel. So I decided to exploit this display and have the data stream wirelessly from a transmitter connected to the OBD-II data port.  For the transmitter, I tested the OBDLink MX+ scanner because it employs Bluetooth v3.0 with EDR (Enhanced Data Rate) to maximize data sampling speed. The transmitter automatically makes a secure wireless connection (no passwords) to my iPhone and does not interfere with other Bluetooth operations, such as handsfree calling or music streaming to the vehicle’s sound system.  The wireless data stream of engine parameters is interpreted and displayed by the included OBDLink smartphone app (for iOS and Android phones), which has a completely customizable graphics interface that is simple to modify. The OBDLink MX+ is able to transmit all standard OBD-II codes plus advanced Ford-specific codes, so a comprehensive range of parameters can be monitored in our Ford V10-powered motorhome.

The most important information I wanted to observe is the calculated engine “load,” which is directly correlated with strain on the engine and inversely correlated with fuel economy.  By monitoring load, you can learn driving and shifting habits that put less wear on the engine components and improve the fuel economy and torque.  I customized my OBDLink app dashboard to display analog dials for load, torque, power, and real-time fuel economy.  I also added four digital readouts to augment my RV dashboard display:  road speed, current transmission gear, battery charge level, and trip fuel economy.  The only duplicated information is on my RV’s speedometer (a rather dim analog gauge), so the other seven gauges on my iPhone screen show information that is normally unavailable to the driver.

The result is a nearly instantaneous readout that is easy to interpret at a glance while I’m driving. There is significant phone battery drain from the constantly working display, but my battery remained charged because I keep the iPhone Lightning-USB cable plugged in to power music streaming and sometimes GPS navigation.  The transmitter never had trouble connecting automatically to the phone once the engine was started.  The app can run in the background and did not interfere with phone calls or any other phone operation.  The scanner can also be easily unplugged and used in different vehicles, just like its companion smartphone.  Portability is especially practical because the OBDLink scanner and app can also be used to diagnose trouble codes from dashboard warning lights (like the dreaded and mysterious “Check Engine” symbol).  The OBDLink app has other useful functions including mapping, time-based data recording, and trip logging, though I focused my attention on using my customized gauges for real-time monitoring of engine and drivetrain performance.

I’m enjoying the displayed data stream, though I still need to see if it meaningfully changes any of my driving habits – modifying when I downshift, how fast I accelerate, my speed on freeways or in hot weather, how I drive at high altitude, etc.  The OBDLink MX+ scanner and companion app cost about $70 (full disclosure: the manufacturer provided a free unit to me for evaluation). It will also be interesting to see how long I actually use a real-time monitoring gadget to improve my driving.  After all, I used to have my smartwatch alert me to every email, then decided it was too disruptive; I used to check my steps throughout the day, and now I just look at the total in the evening to see if I’ve earned dessert.  The benefit to fuel economy may be obvious sooner rather than later; the benefit to engine lifespan is probably something I will never know.