milleplod wrote: ↑15 Jan 2017, 10:27My C5 autobox is exactly the same in that it sometimes seems to need a second or two to work out exactly what its supposed to be doing. I can predict when its going to happen though....at a particular local junction, for example, where I'll be approaching on a closed throttle, slight downhill incline....I take a view, its clear....foot on accelerator....and wait for the box to have a good old think about things! Of course, its only a second or two, but feels like an eternity!
The interesting thing is that our previous automatic cars all did exactly the same sort of thing at the very same junction
This delay can be very annoying. It mainly happens when the throttle is closed and you are coasting such as when nearing a roundabout.
This is how it went for me when I first got my C5:
Slowing for a roundabout, spot a gap, release brake and apply some power.... nothing.... apply some more power... nothing.... push the pedal nearly all the way because that gap you spotted on the roundabout is shrinking fast and there's not enough room to come to a stop now... then all of a sudden the revs jump to 3000 rpm and it's off! makes you look like an idiot with passengers in the car
I've since learned to 'tickle' the throttle as you're coming up to a roundabout as that seems to give it a head start when you do call for some power.
I'm still curious as to the cause of the delay. To my mind the delay appears to be electronic, rather than any quirkyness to do with the torque converter.
The engine just doesn't rev for that one or two second between putting your foot down and the car responding. I'm wondering if the gearbox ECU can veto the demand for power momentarily as it declutches / reclutches or does some other operation that would be interrupted by a sudden increase in power?
I'd be interested to hear from others who have driven an Auto (new or old) about this behaviour and whether it is not present on cars without fly-by-wire throttles.