We now have a different knock sensor system (bolt on sensor) Prolly going to take a bit of tweaking to get just right for all.
The old design (Delphi ION sensing software system) calculated, based on tables, and other routines to determine if a combustion was good or bad whereas the new system measures actual engine vibration similar to most vehicles today.
Here in Cali we are strapped with 91 swill with alky added for good taste so we notice more heat and detonation issues than those with 93 octane without ethanol.
A little time will sort out the new knock sensing system.
Hopefully we will be allowed to adjust the knock sensitivity for build that require it.
Bob

 

The old system on the TC's was an ION sensing system. It was slower and only had one response which was to cut spark advance back 10 degrees for a set time.

The new system uses a microphone. It reacts rapidly and only cuts back spark sufficient to eliminate the problem. It is part of the many engine heat strategies that H-D incorporated to reduce engine heat. The more retarded the ignition the hotter the engine will run and the less performance.

There is nothing in either system has to learn or be fiddled with. Both were perfected long time ago.

By the way 10% alcohol content in gas reduces pinging. Just read what Moto GP says about why the Sunoco Race Fuel they use has it. Kevin Cameron wrote the article.

 

91 octane and no ping here. Weird your getting it..

 

So how was the ion sensing slower then the microphone setup??

What does the new system do that the old system does not?

IMO either system has to be learned and fiddled with if doing performance work.. Stock they are probably OK..

I agree with the 10% alky content.. I runs a few bike with over 210 CCP on Socal gas and they run just fine.. Alcohol has a tendency to raise the octane rating. You need a little more fuel tho..

 

Is it possible that there is too much throttle in too high a gear at too slow of a speed that is causing the ping?

 

found this interesting fwiw

"Sensing, for one thing. The Twin Cam used ion sensors. When getting into different riding positions and heat, you can get detonation conditions. Ion-sensing measures charge in the cylinder after combustion at the spark plugs. However, it has a lot of range to it, though. As you start to retard the motor to compensate for those riding conditions, you lose economy. Ion sensing is not as precise as measuring the knock through an accelerometer-based sensor. So we went to precision knock sensors on each cylinder. When we see one knock, we pull back and not pull too much. That helps with thermal management and fuel economy. You also get more output. It’s an important feature. Combined with the new torque-based ECM, you get smooth and responsive power delivery."

 

As far as I can tell, Ion sensing is nothing more than a simple resistive decay measurement across the electrode on the plug.. While the circuit is simple the algorithm for detecting detonation is likely a bit complex as the Delphi documentation is a little vague.. I know that this system is susceptible to problems if the series resistance of the plug wire / plug internal resistor is off. More important if the insulator on the plug leaks or the shape / material of the electrode change how ions are sensed, false errors can occur.

Accelerometer / microphone sensors likely use much simpler algorithms and none of the above problems. They been around longer. The issue is that they cost more to implement.

Cole or someone with more experience will probably correct me on some of this..

 

Knock sensors are not microphones.

An accurate description can be found here: http://www.freeasestudyguides.com/kn...-symptoms.html

 

Sorry but you don't know what microphone is.. it's nothing more than a transducer that translates a vibration cause by sound to electricity. The knock sensor has the same construction as a some microphones..

The vibrations are nothing more than high frequency sounds.

 

Well I guess you may be right in a very rigid definition of the word. However in a practical sense one would not ask to purchase a microphone from the local Harley dealer nor ask for a knock sensor at the corner music store. I suspect that one would be a very poor substitute for the other hence the reason for each having a different name. In any event the device in question's sole purpose is to sense knock. So let's just call a horse a horse and not confuse people.