VDC not very intrusive?

wstar · 03-15-2012, 10:40 AM

Re manually rev-matching the 7AT:

Quote:

Originally Posted by ImportConvert

I wouldn't. Unless of course you are cool with replacing the 7AT on your dime.

I don't think it would hurt it in the short term to play with it for a few days. They take a lot of abuse and keep ticking, and it's really just some shocky engagements while experimenting.

Quote:

Originally Posted by UNKNOWN_370

I understand that. But I mean functionally. If DRM is disabled or not working properly when VDC is off? And we need to blip the throttle with no manual clutch? How do we still achieve rev-matching manually without computer assistance? That's my question.

SRM isn't disabled when VDC is off. This was just a side-topic that sprung up about SRM being disabled when ETC is off. ETC stands for Electronic Throttle Control, and can only be disabled via UpRev, not dash buttons. In the 7AT case, when you click a shifter paddle, after a short delay the compter goes through a sequence of clutching out of the old gear and into the new gear and blips the throttle in the middle. The question is whether it's practical to time that out manually and do it yourself or not. It's definitely theoretically possible, just possibly impractical.

The Service Manual has some pictorials about the underlying processes, e.g.:

The last line there "Engine Speed Control Demand" basically means "The time window for which the TCM wants to control your throttle for blipping purposes". With ETC off it can't do so, and you have to do the same with your foot.