Quote:
Originally Posted by Nezil
But my point is that boost would build up much quicker than 1.3 seconds if only the waste gate would close. You can see the change in boost pressure rise happens suddenly once the waste gate closes, but it's a full second after you're back on the gas after a shift... And you can feel this when driving very easily.
I guess what I'm saying is that I expect some lag from a human shift being slow; it's inevitable, just as you say.
Throttle closes, DV dumps pressure and the waste gate opens all as soon as you let off the gas. Boost pressure drops dramatically and once you're back on the gas the pressure is way off target. You explained it well and it all makes sense.
What doesn't make sense to me is what happens once you're back on the gas - isn't the waste gate delayed closing behaviour making the situation far far worse (1 second more lag) than it needs to be?
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Hi Nezil, noticed you updated days ago, but didn't have time for a second look at log until now.
The WG behavior does seem abnormal. As when pedal fully back on, the boost delta is big enough to warrant a 100% WG duty but it held back a little to 80%.
Has it been consistently that way?
I suspect the safety action was still being taken at that moment, if the unsettling RPM is any indication. It could be the clutch not being fully engaged or the uneven road surface (less likely as I know what log would've been like).
WG is 100% for a short time (when RPM settles) before it goes down to 80% again which is normal - when boost is close enough to target, WG% goes down to prevent from overshoot, something you can find out for yourself if you floor it off boost and from low rpm.
Please take a look from other logs, specifically at WG behavior after 100% pedal.
In the end, I'm positive 100% WG won't solve the problem with 1.4s shift...Key is still off pedal time. As you see from DCT log, the system is able to hold boost during shift and for most of the time is dealing with overboost.
Thanks
Sean