Throwing Codes | COOK'S CORNER

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.