Dominic Sorresso

So I have been chasing knock retard that appears to happen at a very specific rpm/map range. I have attached a jpg showing an instance where knock retard is occurring but SA however is not being reduced even tho the log shows that KR is being invoked. Someone want to explain?

ULTM8Z

I know in 8D, there's a table that limits how much timing the ECM can pull. Perhaps the analogous table in your calibration accidentally got zeroed out?

Dominic Sorresso

I know I have reduced that table but not zeroed out because I wanted some level of protection. The stock table is a bit overboard. But I guess my question is that of it shows that the ECM is retarding timing by say 2* why am I not seeing the resultant SA showing up in the log. When it starts to pull timing, shouldn’t the SA be the net of the KR?

RBob

iTrader: (1)

There isn't enough retard to easily see the SA reduction. It looks like the line right before the yellow area is at 15.52°, the next line being 15.47°.

The MAP is decreasing and the RPM is increasing, both of which will typically have a higher SA.

Then with the spark loop running at 80 times a second, and the laptop data logging at 7 times a second. It is easy for the SA value and the retard value to be mis-synced.

RBob.

Dominic Sorresso

Thanks RBob. I will check further down the log to see if there is any evidence of retard altho it sounds like it may be missed by the logging rate vs spark loop rate. It looks minimal in any case. Dropping SA definitely has an effect on the KC/KR I log.
Again, it appears to be pretty specific as to the rpm/map region of the SA table. I’m a bit puzzled that I need to drop SA in this area only that at some points is actually below stock SA.

84Elky

In addition to what RBob said, could there be higher SA values in your table at the RPM and MAP during the retard, than just prior to it. Might review that because don't see how it's possible for code to not reduce SA by retard amounts. Also, does your mask have spark coolant bias? If so, could there be a mismatch between the bias Scalar and the spark correction table value at the kPas reported during the reported retard?. For example, if the spark coolant .vs. MAP table value exceeds the Scalar bias value at a given Temp & MAP, SA would be increased by that difference before knock retard would be subtracted, making it look like SA not being reduced. Given the coolant bias delta is usually small and because your retard is small, one could be offsetting the other making it look like SA not reduced.