Power Vision Information Thread
#941
#942
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It will show in the log as Spark Knock F and Spock Knock R. I believe in the selection it says Front Spark Knock Retard and Rear etc. You are looking for where the bike retards the timing you have so PV tune can adjust the timing back in your calibration. Pick the Retard channels for logging
Spark Knock F = Front Spark Knock Retard
Spark Knock R = Rear Spark Knock Retard
Spark Knock F = Front Spark Knock Retard
Spark Knock R = Rear Spark Knock Retard
#943
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Knock retard or (KR) is the number of degrees the ECM is retarding your ignition timing in order to eliminate knock. There is a knock sensor mounted to each cylinder and when the sensor detects knock, it instructs the ECM to retard ignition timing to prevent knock.
If you are logging and you see no KR, then you can advance timing a little, then log again (especially log at Wide Open throttle or WOT). Keep advancing timing until you see some KR happening, then either back off the timing or add a few points of fuel to see if you can eliminate the KR.
The most power you will get is when you are running just on the edge of KR without actually seeing any in the logs. Quality of Fuel will play the biggest part in logging for KR because if your timing is advanced and you put in lower quality fuel, your knock sensors could go ballistic and you actually end up losing HP and performance bcause the ECM is compensating for the Knock by retarding your timing.
If you are logging and you see no KR, then you can advance timing a little, then log again (especially log at Wide Open throttle or WOT). Keep advancing timing until you see some KR happening, then either back off the timing or add a few points of fuel to see if you can eliminate the KR.
The most power you will get is when you are running just on the edge of KR without actually seeing any in the logs. Quality of Fuel will play the biggest part in logging for KR because if your timing is advanced and you put in lower quality fuel, your knock sensors could go ballistic and you actually end up losing HP and performance bcause the ECM is compensating for the Knock by retarding your timing.
#944
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Actually, most (all?) knock detection today has no external hardware mounted to the engine block to detect knock. Ion-sensing knock detection, the method used in Harleys at least as far back as '07, does not use a sensor that is externally mounted on the engine. The name "ion sensing" is derived from the fact that as detonation occurs ionization at the plug tip changes the resistance to fire the plug. The actual detection of this change in resistance is internal to the coil and the signal is sent back to the ECM.
#946
![Default](https://www.hdforums.com/forum/images/icons/icon1.gif)
Actually, most (all?) knock detection today has no external hardware mounted to the engine block to detect knock. Ion-sensing knock detection, the method used in Harleys at least as far back as '07, does not use a sensor that is externally mounted on the engine. The name "ion sensing" is derived from the fact that as detonation occurs ionization at the plug tip changes the resistance to fire the plug. The actual detection of this change in resistance is internal to the coil and the signal is sent back to the ECM.
#947
#948
![Default](https://www.hdforums.com/forum/images/icons/icon1.gif)
Actually, most (all?) knock detection today has no external hardware mounted to the engine block to detect knock. Ion-sensing knock detection, the method used in Harleys at least as far back as '07, does not use a sensor that is externally mounted on the engine. The name "ion sensing" is derived from the fact that as detonation occurs ionization at the plug tip changes the resistance to fire the plug. The actual detection of this change in resistance is internal to the coil and the signal is sent back to the ECM.
I logged a number of good runs that varied alot. The dyno-tuned map was pretty good from a spark perspective but there were a few areas where there were small knock events. Mostly out near 70-90 kpa and 3500-4000 rpms. Again these were relatively small events but I thought I would let the Tuner make the appropriate adjustment.
The tuner lowered the spark and when I logged again the knock event was either gone or reduced to nearly nothing. What I did notice was that the performance of the bike from just this small timing adjustment made a noticeable reduction in performance that could be felt from the saddle.
Is it possible that the basic tuner algorithym is too aggressive in lowering the timing when it reads a knock event. In any case I went back to the original dyno-tuned map and immediately felt the improved performance. Is it possible that PV tuner is lowering the spark advance more than the ECU knock retard is lowering it which is why I feel the reduced power?
#949