Throwing Codes | COOK'S CORNER

What do you do when your bike's computer is smarter than you?

I learned something interesting about my long-term Suzuki V-Strom 1000. Finally tempted to try a slip-on muffler by Dale Walker of Holeshot Performance, I thought it might be useful to install a Power Commander to refine the fuel curve for the exhaust and, just maybe, get rid of the occasional glitch in the bike's low-speed fuel delivery.

Because the V-Strom has oxygen sensors in both head pipes and the Power Commander setup would prefer the stock ECU to not use them to alter the fuel/air ratio, the kit comes with two plugs that “fool” the ECU into thinking the oxygen sensors are providing a set feedback. The installation went really well and I rode the bike home with the zero map in place. (In case you haven’t used a Power Commander or similar injection tuner, a zero map simply passes through everything the stock ECU is trying to do. When you change a map, you add or subtract fuel in cells defined by throttle position and rpm.) As expected, the V-Strom ran just like it did stock.

But about halfway home, it “threw a code.” Modern engine computers are capable of what’s called on-board diagnostics. When something goes wrong in the system, the ECU records an error code, lights a warning on the dashboard, and stores that information for later retrieval. In the case of the V-Strom, it lit the “FI” light in the tach face and alternated whatever was in the top mileage display—usually total miles or one of the tripmeters—with the word “FI.” The bike continued to run fine so on I went.

A trick that used to work on some cars and bikes was to remove the negative battery cable for a short time to clear codes. I tried that, to no avail. I was starting to get cranky, certain it was a transitory failure and that I shouldn’t have to stare at a right light all day.

After quite a lot of back and forth with Dale Walker, who was much further down the experience trail with this than I was, I learned that the current Suzukis hold the FI codes and won’t extinguish the warning even if the problem fixes itself. As a test, I removed the Power Commander and restored the connection to the oxygen sensors.

Still got an FI light.

Finally, I had the bike taken back to Suzuki’s US headquarters to have the light reset and the fault codes read. Turns out, it was my doing all along. Apparently, when finishing the Power Commander installation, I missed reconnecting the air-temp sensor. The ECU saw this as a failure of the sensor and kicked out a fault. So it had nothing directly to do with the Power Commander. Whoops.

There are many lessons here.

  • Double check your work.
  • Be aware that today's ECUs look at everything. A sensor out of spec or even temporarily disconnected will cause the system to throw a code. And, at least for the most recent Suzukis, there's no way to reset the code on your own without tools. The old trick of removing the negative battery cable and waiting just doesn't work.
  • Get friendly with your local Suzuki dealer if you plan to modify your bike. I'm told that customers with good reputations at the service counter—something I do not have, since they hardly ever see me—might get codes read and fault lights reset as a courtesy. But it'll run $40-50 for the tech's time to hook up the Suzuki tool, read the codes, and reset the warning if you're just some guy off the street. And, it should be said, the Suzuki techs are trained to make sure that whatever fault found by the computer is actually fixed; so your service visit might be longer and more expensive if something is wrong beyond a sensor left un-connected.
  • You can buy the box Suzuki's techs use for about $200-250. This is probably a good investment if you're planning lots of mods to your machine.