knock sensor

[twodealdrive]

I've got a '99 with a PC2 and 38k on it. It used to belong to Vern (xrated). Great bike, has been well taken care of. But lately, the last month I'd say, I keep getting the FI light with more and more regularity, especially when I ride in the rain. Which would make me suspect a connection or wire. The code is always 25, the knock sensor. I've checked the connections from the PC2 to the ECU, I've done the '99-'00 wiring loom fix, I've left the neg cable off the battery for 15 minutes. The FI light comes after about 10-15 minutes of running. I can feel it effect the performance of the bike. It's a noticeable loss of power when your cruising along at a steady throttle.

Anybody have any suggestions as to what I should try next? I'm pretty handy and do all my own maintainence, so I'm willing to give most any idea a try. Is there some wiring I should check, or is it the sensor and I should just replace it? I've also downloaded the manual but I haven't found the sensor yet. I usually burn 87 octane and haven't tried any higher grade to see what that would do.

Thanks in advance for the help.

UPDATE: I found the knock sensor location on the engine under the gas tank. Details are on page 40 of chapter 1 in the manual, if anyone else is interested. Also found part # and price for new one from Ron Ayers.[attachmentid=2922]

[ironmike]

I don't think I've heard of one going bad... Have you tried disconnecting the PC2 and seeing if you get the same codes via the stock ECM..?

:icon_think:

[mikesail]

I've done a couple threads on this topic. search for knock sensor and you'll see some of my conclusions.

I'll bet that it is just becoming disconnected, pulling the plug on my bike does cause the FI code to display.

the sensor absolutely affects power and mileage.

And it takes a 24mm deep socket to remove.

[twodealdrive]

I've done a couple threads on this topic. search for knock sensor and you'll see some of my conclusions.

I'll bet that it is just becoming disconnected, pulling the plug on my bike does cause the FI code to display.

the sensor absolutely affects power and mileage.

And it takes a 24mm deep socket to remove.

I've read your posts and found them helpful but not totally for my situation. But it is good to know a little more about the knock sensor and it's function.

I'm going to look into the PCII next and make sure all the latest software is downloaded to it.

Mikesail, you used a rubber O-ring as a washer?

[mikesail]

I used an o-ring as a washer because I wanted to decrease the vibration to the knock sensor. My goal was to prove that the sensor was affecting the power. And it was.

But you bike showing a code leads me to suspect that the wire is likely disconnected. My sensor was putting out too much signal, and this does not report a fault.

[twodealdrive]

But you bike showing a code leads me to suspect that the wire is likely disconnected. My sensor was putting out too much signal, and this does not report a fault.

The knock sensor was hooked up. I took the PCII out of the loop and no more knock sensor code. I hammered on it during my test ride, which previously would trip the code and red FI light almost right away. I'm not sure if riding in the rain got the PCII wet and caused the problem or if it needs the firmware update. I'll try the software download and see what happens when I put the PCII back on-line. Thanks for the help.