This page contains a few notes on things that caused me some trouble in the past, so I'm hoping to save someone else this hassle in the future. These are little adjustments that you can do yourself in 5 minutes, but for which you'd be charged $100 if you took the bike to a dealer.
Like all things mechanical, they'll drive you crazy if you're all alone, but if someone can show you how to do it, it's incredibly simple.
The TPS has to tell your ECM, the main computer of the bike, exactly where the throttle is. The ECM can then look up this position on your fuel mapping table, and deliver the proper mixture of air and fuel to the fuel injectors. If the computer thinks you're at full throttle, and you're only at half throttle in reality, then the ECM is going to send the wrong fuel:air mixture to the combustion chamber.
The bottom line is that you have to give accurate information to the ECM if you want to get maximal power and performance. So you have to make sure your TPS is calibrated correctly. Here's how to do it.
On a side note, do not get this confused with the procedure for calibrating your TPS setting in the Powercommander©. That must also be done. But this page refers to actually calibrating the sensor itself on the bike.
You need a Dealer Mode switch to be able to adjust your TPS. So install that first.
Once that is done, locate your actual TPS on the right side of the bike. This drawing shows you the general area where you'll find it. The TPS is located at the end of the red arrow. Yep - it's hidden by the gas tank, so you'll have to remove the gas tank to get access to it.
The shop manual dscribes the TPS adjustment very clearly, on page 4-30.
Both the STPS and the TPS use a T25 Torx screwdriver for their adjustment. This is the "special Suzuki tool" mentioned in the service manual. Get one at your hardware store for a few bucks.
Here's a real life picture of the "secret Suzuki Tool", a $2 torx T25 I bought at Best's Hardware Store, Lewes DE. And right there you can see where it goes. If you're putting it anywhere else, it's not the TPS ! Don't mess with the STPS by mistake -- then you'll end up getting a C28 error and a ratcheting sound when you turn the key in the ignition...
Just to eliminate any confusion in these pictures, let me explain. On these pictures with the curved yellow arrows, those arrows don't point to anything, they are only meant to show the direction you TURN the TPS before you screw it down, and the effect that has on the TPS setting.
For example: this top picture is meant to show that when the TPS is turned too far clockwise, or DOWN, it will have the effect of making the TPS look "too low" on the speedometer. Then you would turn the TPS counterclockwise or UP, to correct this.
When you turn the TPS counterclockwise too far, it will make the TPS look "too high" on the speedo. The correction you would want to make is to turn the TPS clockwise a little bit , or DOWN, then tighten the torx screw.
... and the baby bear's bed was jusssst right...."
This is how your speedo should look when the adjustment is perfect. So quickly tighten down the T25 screw before the thing moves again!
After you have adjusted the TPS with your Torx screwdriver, your ECM now correctly "knows" when you are at 0 throttle and when you are at 100% throttle. That's important for the ECM to send out the proper amount of fuel to the injectors.
But now you have to "tell" the power commander when the throttle is 0 and 100% open, so it also can be calibrated to send the proper signals to your ECM. You're now ready to calibrate the TPS setting in your power commander software.
The procedure below shows how to calibrate the TPS settings in your power commander software.
Just hook up the power adapter to your power commander, hook up your 9-pin serial cable from your serial port on the laptop computer to the female connector on your home-made adapter, then turn the ingition key without starting the engine. Of course you fancy younger guys have the USB Powercommander, so you connect with a USB cable instead of standard serial cable.
The bike is OFF for this procedure. Important! you must have the kill switch (right handlebar) set to RUN, or this won't work. Also, you must have the Powercommander connected, with the ignition turned to ON (without the engine running), and you must have a power adapter with 9V battery attached. If all these things are not done, the "set throttle position" option in the software will not be available in the "utilities" menu.
If you've made sure all those things are done, , now go to the Power Commander software, click on "utilities". You'll see "Set Throttle Position". Click on that and the the dialogue box shown at the left will pop up.
With the throttle and choke (if applicable) closed, click on "TP Closed" button .
While holding the throttle all the way open, click the "TP Open" button, then click the "OK" button.
YOU'RE DONE! Now roll the throttle all the way closed, and all the way open, and watch the numbers at the top of the computer screen change. When the throttle is closed the %Throttle on the Commander Center Monitor should read 0, and when it is all the way open it should read 100.
If you're clueless with the Power Commander software, no need to worry. They have some very good animated tutorials to get you in the right direction - check these out. And you can download them to your laptop, to use in the garage.
c28 errors are common. You can pursure the checklist of items as shown in the service manual, but I would recommend doing something else first. A common source of a c28 error is actually not mentioned anywhere in the service manual: a miscalibrated STPS. Adjusting the STPS is easy, and will take you 10 seconds with a T25 torx screwdriver and a multimeter. You might expect a miscalibrated STPS to give you a c29 error, but that only happens if the sensor is broken or shorted out, not if it is miscalibrated.
So if you're getting a "c28" error, BEFORE you do anything else, check the resistance at the STPS coupler and make sure it is 500 ohms on the nose. If that is correct and you're STILL getting the c28 error, then go down the c28 checklist in the manual .
If you hear a ratcheting, clicking sound after you turn the key in the ignition, and after the fuel pump primes the injectors (the normal machine-like sound you hear before you start the bike), then that ratcheting sound is telling you that you have to adjust your STPS.
If you're really popping up the c29 error, that inicates a problem with the STPS circuit, which will take some investigation. Check the procedure posted at left.
Sorry I'm not a mechanic. I thought it was important to post these notes here because I've had these troubles before. But if the maneuvers posted here don't solve your problem, then I do thing it's time to take her to the dealer. Sorry I won't be able to walk you though any more steps than are posted here, just because I don't possess any more knowledge than this!