Originally Posted by illinipo
SBAF6 has two DMRs that are described as KNOCK SENSOR RETARD LIMIT. I've talked to SCT about this at least 10 times over the last 3 years and all they have done was change the name of one of them, not the description. You need to take a closer look at the names, or download the latest livelink if you cannot see the difference I outline below.
KNK_RET_LIM is the first one. There is a table in the ECU with axes of RPM against load that simply limits the amount of knock retard you can get. It is -5 in almost all cells, with a few at low and high rpm at -4. The reason you are seeing -5 on this DMR only when you are moving or transbraking is the sensor is not allowed to be active at all until 0.359 load, and you would be hard pressed to see that much load without the car in gear (Tom already metioned this earlier in the thread). So basically whenever you are driving, as you describe, this should rightly show -5.
KNK_SEN_RETARD is the second one, the one you actually want to log, this is the actual knock retard. This one you ought to be able to at least see it ramp down (instead of jump down) to -5, and ramp slowly back up (instead of jump up) when you let off the throttle, if it is indeed pulling full knock retard.
You and Tom are both right. Thanks for the awesome detailed response though!
It turns out the right KNK SEN RETARD was being logged. I had the view on the "long name PIDs" setting instead of the "16 Char Name PIDs". In the long name veiw, both DMR's show up exactly the same as "KNOCK SENSOR RETARD LIMIT" but for some reason the correct one to be logged comes up first in the PID list. In the 16 view, the correct one comes up second on the list?
But yes, the graph shows a short little spike (about 0.6-1.0 advancement) then drops straight down to -5. Just waiting for my new one to see if anything changes.