I have made progress in reducing the torque management advance (TMA) by RPM Limit Accel Thresh vs. Accel. However, there is still some TMA remaining. I suspect there were multiple sources for the TMA — we solved one. My next hypothesis is that there is some torque management advance coming from boost rate of increase exceeding the allowed pressure delta.

I see in the prior graphs that when there is torque management advance there is also rapid boost increase. I assumed that this was due to the TMA, but it got me wondering if the rapid boost increase was actually a causal factor for the TMA.

I am not clear how Cadillac calculates rate of boost increase. To try to model the rate, in the graph above I first graphed the limit in blue. Then I considered a rate of increase per 0.1 seconds from my log 1E. In other words, what was the % of increase in boost over 0.1 seconds? I graphed that in red. Finally, where do we see TMA on the same run? I graphed that in gray. I can see that the TMA correlates with the boost increase rate. Correlation does not equate to causation, but it is a clue.

My next test will be to increase the Pressure Delta Factor to determine if that has an impact on torque management advance.

This tune had a couple of fixes to try to eliminate the torque management advance. They were partially successful.

Previous run showed two spikes with up to 12 degrees of torque management advance; this run had one spike with only 4.2 degrees. Although there is still some TMA, this was progress.

I have been showing the graphs as xy graphs, hp to rpm for example, which is the way a dyno might show similar data. However, this does not consider the time aspect — it takes much less time for the engine to get to 4500 rpm than from 4500 to 6500 for example.

This shows time offset from hptuners scan along the X axis instead of RPM. My impression is that they are time in seconds of the scan. It is time correct, and RPM builds from left to right but I have not discerned a best way to show both the HP vs RPM and HP vs TIME on one chart yet.

This second chart is useful however for understanding when events occur in time — go WOT, tip-in and boost, torque, and RPM build rapidly. A largely flat torque curve that matches the boost curve.

The remaining TMA retard appears to coincide with rapid boost development. My next test will be to see if that is a limiter.