This does not happen all the time, but when it happens I can surely feel it - it is like the bike does a 'hiccup' on power delivery, then quickly recovers.
It can be seen in the log (see screen shot), basically what happens is that when you close the throttle the spark advance quickly goes to zero and then comes back to where it should be.
It is not a 'knock' event, it is something different. Can it be the 'closed throttle spark' function acting up? I have those tables but there is not a sigle 'zero' in them anywhere...



by the way bike is a street glide (117") with a 824 strategy/map.

 

What year? Can you post the map currently in your ECM?

 

it's a 2019... here's the map I was running when that log happened. file says '.txt' but it is actually a .pvt (powervision). Could not attach it as .pvt
will upload another to the bike later today with the 'closed throttle spark max tps' set to zero to see how it behaves.
interesting that the description says '0.5 to 0.9' but the value (got this from stock IIRC) is 1.172. close enough I guess

 

The 19 CVO uses torque management in the background- I wonder if that is what's affecting it?
Entirely possibly it's simply a decel fuel cut off occuring, causing that sensation.

 

I guess you nailed it - fuel cut off. It happens regardless of the closed spark table thing being disabled. I am at a loss why it also pulls all the timing during this cut off, and why it does add it back gradually when it exits the cutoff state. Guess i'll have to play with that if even possible.
The only side effect I felt running with the closed tp spark tables off is that the bike appears to behave better at lower RPMs, like 1500 and under. tables probably not set up right because I messed a lot with the main spark tables and did not pay much attention to the closed ones.

vv

 

well, I was checking the DFCO parameters for my map (which from what I can see are the same of all other touring M8 maps that I got from DJ website, and also the same as the map I got from FM) and I think they are stupid

The parameters translate to the narrative below, which is *exactly* what I see in the log.

When the throttle is closed (tgs < 1.6),
IF rpm > 2400 and engine is not dead cold (> 45 degrees C) and map < 18.1 enter fuel cutoff IMMEDIATELY;
WHEN rpm < 2050 (as it will quickly be if you keep throttle closed) drop spark advance to 4 degrees (minus the temperature based reductions it gets to be zero) IMMEDIATELY.
IF RPM < 1800 or tgs > 1.9 or map > 22 -> exit DFCO mode (injectors are reactivated and spark goes back to normal).

maybe I'm 'driving my harleys wrong', but the way I do it when driving lazily this will happen a lot of times, I shift between 2500 and 3000 and roll back the thottle when doing so. And I never feel this hiccup on the sportie (from what I see in her map this feature is disabled) or the electraglide (which is tuned with TTS and I dont see DFCO stuff anywhere in their calibration, maybe also disabled).

it does not seem to be a bad thing to do, but the IMMEDIATELY part is what I think it is totally bonkers. fortunately there are parameters to deal with this, so I changed it to work like this and will test tomorrow :

When the throttle is closed (tgs < 1.0),
IF rpm > 2400 and engine is not dead cold (> 45 degrees C) and map < 18.1 enter fuel cutoff AFTER 2.4 seconds (number totally pulled from my ****).
WHEN rpm < 2050 drop spark advance to 4 degrees (minus the temperature based reductions it gets to be zero) AFTER 0.5 seconds (also from **** - might never happen).
IF rpm < 1800 or tgs > 1.5 or map > 22 -> exit DFCO mode (injectors are reactivated and spark goes back to normal).

there are other stuff about adding extra fuel based on how long it was cut off, but I left it as is (all zeroed).
the changes on tgs cut points I based on what I see in logs... dead closed seems to be 0.6 so < 1.0 looks more appropriate (not sure why original is <1.6, but all maps are).

hopefully these changes will limit the cutoff to when I am actually going downhill and engine braking... will know better tomorrow if weather helps

 

You may notice a bit of change as you slow for a stop sign, as DFCO in/out affects that area, too. This helps with what is commonly called "decel pop".

 

well just tested and no more hiccups - confirmed in datalog too
this and the disabling of the wrong closed throttle spark table made the bike behave much better... I was kinda used to the quirks but it's better without them - happy camper here

as to 'why oh my' we have defaults such as those... mysteries of life I suppose.