I had so many octane code last w-e so i've decided to check the torque of the sensor and was very surprise when i checked it: near 30lbs! Not suppose to be 15lbs ???
Knock sensor
- Thread starter fishhunter18
- Start date
Well, problem's solve. Sensor too tight....
been running into code 21 knock sensor failure all winter, after new top end, and rk tek head install. some times it comes on at start up (idle), sometimes it comes on when riding. shut it off, open hood wiggle harness, will be ok for a bit but, sooner or later comes back on.
found the wiring diagram figured the pin out, cut harness approx. 6" from ecu connector, cut, harness near sensor to eliminate all connections but, the ecu pin. went for a test ride on a rough trail, no code for close to 15 miles. came home, installed the plastic conduit, taped, and zip tied in place... next ride, less than 1/4 mile, yep, you guessed it... CODE 21, KNOCK SENSOR FAILURE.
it doesn't run any different with the code, it just bothers me the code is on, blocking the cluster info for everything else. I am pulling my hair out. help is appreciated. Ski
found the wiring diagram figured the pin out, cut harness approx. 6" from ecu connector, cut, harness near sensor to eliminate all connections but, the ecu pin. went for a test ride on a rough trail, no code for close to 15 miles. came home, installed the plastic conduit, taped, and zip tied in place... next ride, less than 1/4 mile, yep, you guessed it... CODE 21, KNOCK SENSOR FAILURE.
it doesn't run any different with the code, it just bothers me the code is on, blocking the cluster info for everything else. I am pulling my hair out. help is appreciated. Ski
J
jim
Well-known member
First thing to do is figure out if it's real or a false alarm. Before you ride next time, run 2 gallons of av gas or race gas in your tank. See if you still get it. If it stops, you really were knocking. If not, you may have a sensor issue. You should be able to check the resistance of your stock one...but I don't know what the value should be. Some say you can tap it and the resistance should change? But, not sure.
Also, sure fire thing is to check pistons...make sure they aren't eroding or have pitting. You can check them through the power valve slots.
Also, sure fire thing is to check pistons...make sure they aren't eroding or have pitting. You can check them through the power valve slots.
recently had this exact same scenario. here is the fix. The problem is that the sensor cannot get a good ground through the anodizing.... clean threads, and sand off the anodizing under the sensor... your code will go away.
the code 21 IS NOT a knock code... it is a sensor circuit code... open/shorted.
thanks anylizer, you are right the code (21) is not saying it is detecting knocking, it says the sensor has failed. I have switched sensors with the wife's m8 sensor (same sled model, same sensor, we know it works). so, it is losing contact at some point. my next effort was going to be to replace the ecu pin in the harness but, I like your take on this issue, and it makes sense.
I was told the sensor doesn't really work at idle, and the cluster at start up sweeps to diag the sled, so kicking this code at idle (mine does) is a contact, ground issue. I wonder if you could run a second ground wire from the sensor to a good ground? I hate to mess up that pretty black anodizing.
I run fresh non ethanol 90 octane rec fuel, so I know it is not the fuel. have checked pistons ect... everything looks great. and again, the code is not for seeing detonation, it is saying the sensor failed. knowing I have a good sensor, I am pulling my hair out trying to make the code go away.
Ski
I was told the sensor doesn't really work at idle, and the cluster at start up sweeps to diag the sled, so kicking this code at idle (mine does) is a contact, ground issue. I wonder if you could run a second ground wire from the sensor to a good ground? I hate to mess up that pretty black anodizing.
I run fresh non ethanol 90 octane rec fuel, so I know it is not the fuel. have checked pistons ect... everything looks great. and again, the code is not for seeing detonation, it is saying the sensor failed. knowing I have a good sensor, I am pulling my hair out trying to make the code go away.
Ski
Humm, rode this w-e and problems back damn!!
M8 2011 and brand new without mods with the reflash and only 91 octane, still get the code.
Now i have a can, Boyesen reeds, 1.5 key. Run a lot better but have the octane code between 6000 and 7000 rpm randomly.
Now i have a can, Boyesen reeds, 1.5 key. Run a lot better but have the octane code between 6000 and 7000 rpm randomly.
remove the key, or add a powercommander and richen it up, you may have detonation with that set up... with reeds, and higher timing. 6500 is where the powervalves open, and the fuel curve from the factory is the leanest. I would run higher octane fuel, or pull the timing key, or add fuel via a fuel controller. your results may vary. I am guessing though, you are getting detonation from your set up, and the sensor is working, and picking it up. Ski
It does it stock. Put the can after 2 years of use. Reeds replaced 2 years ago and i just put the key last season so i doubt it's the problem.
APV cleaned every year but what you just said about that remind me that the mecanic didn't replace the power valves cables yet (5000miles). Gonna order new ones and try that next w-e.
Thank's!
APV cleaned every year but what you just said about that remind me that the mecanic didn't replace the power valves cables yet (5000miles). Gonna order new ones and try that next w-e.
Thank's!
Try removing the sensor and mount it on the tin at the top of the steering post, you will need a 8mm nut. This way you will know if it's deto or not. Just don't cruise at that 6500, not that you would just saying.
If no codes after a day riding then you know you have some light deto happening.
If no codes after a day riding then you know you have some light deto happening.
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