Is there any way to troubleshoot the ION Sensing Ignition Subsystem on a 2007 FXDC? This ION Sensing Subsystem checks for detonation and retards the ignition timing if detonation is detected - this eliminates the detonation.

As I posted last week, after my 10k service, I all of a sudden had severe detonation under any acceleration and steady detonation at speeds over 65mph. Three times I had the same scenario: I'd clean the plugs, recalibrate Mode 19 on my FuelPak, test ride the bike on a long ride, and the detonation would be gone. Then the bike would sit for a week, and the next time I'd ride it, the bad detonation would come back. I'd come back in from the ride, clean the plugs, recalibrate Mode 19 on my FuelPak, test ride the bike, and the detonation would be gone. This has happened three times. I am very puzzled why the detonation goes away, then when the bike sits in a clean, dry garage for a week, the next time I ride it, it's detonation city.

I know that the spark plugs, spark plug wires, ignition coils and ECM all play a role in the ION Sensing Ignition Subsystem. Could it be something as simple as I have a bad plug? How come this problem comes and goes like this? The next time the detonation occurs, I will do only ONE thing at a time (clean plugs and if that doesn't fix it, recalibrate Mode 19 of FuelPak) to better use the process of elimination.

Anyone with insight will be most appreciated.

Thanks,
Richard

 

Plugs are cheap. Make sure it's the correct plug from the manual. Don't copy the installed plug in case it's not correct to start with. Something as simple as different temp and humidity could trigger detonation if ion sensing is borderline in operation.
Ron

 

Thanks. At the 10k service the HD dealer installed the correct plugs - ie. HD 6R12s. The next time the detonation reappears, the ONLY thing I'm going to do is change the plugs. If that solves the problem then I'll know I got a bad plug(s) - it has been known to happen. If that doesn't fix the problem, I'll then recalibrate my Fuelpak Mode 19.

Richard

 

Richard
There is no way a fuel pack or any DFO can set the fuel delivery correct in each cell, the DFO or fuel pack takes hundreds of fuel cells and groups them into 4 sections.....any where in this group of cells can be wrong causing the detonation. This is why the TTST is so much better to tune with....it gives you basically what the engineers had to develop the map to begin with. DFO's can not do what needs to be done with your ECM.

 

Doc1,

I agree with you 100%. However, from July 2007, until September 23, 2008, my Super Glide Custom ran perfectly with the FuelPak for over 7,000 miles in all kinds of conditions under all loads and at all speeds. Why all of a sudden is it pinging (detonating) like crazy? I clean the plugs and the bike runs fine for hundreds of miles, and after sitting for a week it pings like crazy again? Like I said, this cycle has repeated itself 3 times over the past 4 weeks. The first time it happened the front plug was white and the rear plug was fine. Now both plugs are burning a very light brown. My question is how can I approach this from a diagnostic perspective? Since being laid off in Dec. 07 I cannot find work in my field so spending significant money is not something I can do now.

Thanks,
Richard...

 

Are you sure that the code is a "Pre-Ignition" issue and not a "No Combustion Detected" issue...

They both act the same... And you cannot rely on the ECM Codes, as you are utilizing an EFI Management Modem, and the Signals are scrambled...

Other issues to evaluate.... Correct terminal engagement on plug wires at Coil as well as plugs... Possible broken/cracked insulator.... Loose terminal cap on plug... If and when all these pass, take the FP out of the loop and try it without the FP...

 

Thanks Shovelhead,

Am not getting any DTC codes on the speedometer DTC check. As I indicated, I cleaned/reinstalled the plugs on Monday, ran the bike hard through all gears up to 85mph, and no detonation - not a single ping. And before I cleaned the plugs and reinstalled them and recalibrated Mode 19 on my FuelPak, the bike was detonating like crazy. This cycle has repeated itself 3 time in the past 4 weeks now. I will make the connection checks and take the FuelPak out of the loop if/when the situation reoccurs.

Also, regarding "no combustion," how do I check? Remove spark plug and crank engine to see spark at the electrode?

Thanks,
Richard...

 

I just noticed a potential issue... You reside in NJ.... No...., That is not the problem....

You are running Winter Fuel currently....

Could be where part of your problem is...

Winter fuel has a higher concentration of Oxygen and Ethanol...

Will affect the combustion process, as well as the FP doing it's thing with the interruption/modification of the ION Sense protocol....

 

No problem Shovelhead - I am no fan of NJ.

I am familiar with the "winter", oxygenated fuel and understand the potential for it to have an effect. I have been putting in just 93 octane Sunoco. I just need to figure out what it is that I'm doing that seems to temporarily fix the problem. I have not ridden this week yet.

Richard

 

I removed the spark plugs that the dealer put in for my 10,000 mile service and put in new spark plugs that I had bought about 6 months ago. The problem has gone away and there is only a slight ping every once in a while. This past Sunday I rode 370 miles with no pinging/detonation. I am guessing there was something with the spark plugs?

Richard