So I finally quit procrastinating and bought the license to tune my SG (stock 117) engine.
Usual drill, put a canned-ish map in and go for some datalog runs, yadda yadda

I see a lot of KNOCK RETARD in the logs, weirdly both cylinders 'knock together' (this never happened on my older TC!), the front always retards twice as much as the rear. is this normal??

what I did so far to get this sorted out was reduce a 'limit' on the knock retard actuation that would prevent it from kicking in below 50kpa (what I was seeing was it kicking in exactly when it crossed 50kpa, so perhaps it was already pinging before... who knows. reduced that limit and histeresis to 30/28kpa).

what is the expected advance when 'on the throttle' for this engine? im doing 24-ish and still seeing some pinging 'mid-throttle', around 50-70kpa at lower RPMs (2000-ish). just keep pulling timing or is my knock detection thing misbehaving (I dont hear any pronounced pinging).

 

You probably shouldn't have done this.
I would recommend reviewing your data log (sort and filter in excel) and find where the knock retard is happening and the highest numbers. Then go into those cells in the VE tables and just add +5 to start with. Just because there are numbers in the knock retard doesn't mean it was pinging. If after you run another datalog and see numbers above 4 or so (especially max), then add some more fuel. Anything below that is not worth messing with. In my opinion of course.. Knock retard is just doing it's job.

 

What and how are you tuning it? Did you get your VE's mapped out before moving to timing?

 

agreed - it's just to help me troubleshoot this thing. the retard goes almos instantly to 6 degrees (max) front and 3 degrees rear as soon as it crosses 50kpa at low RPMs... after I get this sorted I'll put it back to default. Gas here in brazil is 'odd' (crap!) that might be exarcebating the issue.

not really - used the stock VEs from the original tune and just increased a bit here and there. original plan was of course to start with the VEs but all those ping/knock events came as a surprise. since the M8 has real sensors instead of that old 'measure knock by spark plug' thing from the TCs it is probably real, not some ghost reading (used to get those on my 103's front cylinder until I gapped the plug properly).

 

well...

reducing the timing to the point of being ridiculous (engine noticeably weak when hot) and the goddamn 'knock events' still happen everywhere. will have to assume that 'it's the nature of the beast' and simply go back to the stock-ish timing.

to be honest, bike was running well and I could not actually 'hear' any knocking (I could easly hear it on the TC!), so this is probably how it is designed to work anyway. another case of 'if it aint broke don't fix it!'

cheers.

 

the spark plugs will tell you of its detonation. the porcelain will be speckled.

 

yeah... I think I got it figured out, but still think its weird.

those were not actual 'knock events', they are actually caused by some 'adaptive retard' thing that those M8 ECUs seem to have built in. it should be controlled by this table :





which oddly there are two of them (with different values) on TTS software, which I assume front and rear, but in powervision there is only one. by filling positive values in those zeroes to the left-top I managed to have 'knock retard' even at idle in the front cyl (just 0.5 degrees), which is... retarded

apparently the right name for this table is 'adaptive knock retard limits' and it applies over a hidden table that remembers where knocks happened (and boy, they DID happen with the stock tune and shitty gas I have been running for the past months), and it is easy to see why 'retards' would kick in at 50kpa - until 48kpa the 'allowance' for the 'learned table' to interfere is zero, then it opens the floodgates.

in theory the other 'invisible' table should start 'reducing' over time if the base timing is correct. it is actually a clever idea, to introduce a retard if you get a batch of inferior gas, etc, then go back to normal over time. my problem is that I run bad gas all the time and my 'learned' table is probably full of retardment.

so, new plan... zero out all of this table and deal with the ACTUAL knock events that show up, then put it back on (perhaps a bit different limits, we'll see).

 

I hate he fact that all these tuning software companies don't give full control/access to every table in the ecm.

 

agreed! - it should at least give you the option to 'clear' this spark adaptive table like it does with the adaptive VEs when you load the map, but looks like it does not.

 

I wouldn't trust any knock detection with powervision. It doesn't work right. Never has.
Not the only thing that doesn't work properly with powervision either. The crank tooth setting doesn't work either. That's why it's unavailable except to certain dyno tuners.