[Nezil]

I can't remember who posted it, so I apologise for not giving credit where it's due, but I'd heard it suggested that the lag between shifts with the 6MT is a software thing, and not true turbo lag.

This bothered me quite a bit, mostly because it went against established thought, including my own thoughts on the subject, but it could explain why this lag between shifts

a) doesn't improve by making engine modifications that in theory should
b) doesn't happen when shifting above 6,000 rpm.

I'd also heard that this phenomenon also happens with the M2C. The S55 is fundamentally very similar to the N55, but the induction system is different enough that I'd expect a different characteristic between shifts.

So I started investigating this a little deeper by looking in to some logs. These logs were captured with 100% accelerator pedal input, shifting from second to third but before 6,000 rpm.

I'm no expert at reading logs, but it appears that the Waste gate Duty Cycle trace shows the waste gate opening after I've got back on the gas, for a period of 1 second. This prevents boost from building until it again goes to 100% duty cycle and boost again climbs.



I have some questions then about this finding:

• Can anyone comment on if I'm reading this log data correctly?
• Can anyone comment on if the 6MT S55 M2C also has this behaviour?
• Can anyone comment on if the DCT OG MG (or M2C) has this behaviour if you shift manually below 6K rpm whilst flooring it?
• If this is a software defined / controlled behaviour, can it be fixed or improved in a tune?