Automatic trouble
I run a Vauxhall Meriva B 1.4 turbo automatic. I’m quite happy with this car although fuel economy is not that good. A recent rescue mission to Heathrow Airport returned just under 40mpg! While on the motorway doing 60mph I floored the accelerator to pass some traffic and the gearbox seemed to change right down to first gear (it has six) and the engine revved its nuts off with seemingly little acceleration!
Can I stop this from happening again apart from lifting off or using manual selection? Does this gearbox have an ECO mode? It is an Aisin Warner TF80SC AF40. John Thompson
The transmission unit in your Meriva is a very complex unit and in some ways can be compared to the VAG DSG and Ford Powershift type gearboxes, it shifts gears using the Lepelletier arrangement. This means that the gear change is managed by the computer program within the self-contained control module. The completion of the gearchange is achieved by one clutch engaging at the precise moment that another is disengaged.
The problem you encountered is quite rare and the best move would be to get the gearbox codes read to determine the cause – this could, I suspect, be the incorrect information from a speed sensor, but may be due to one of many different possible sources.
The problem could also have been one of the clutches slipping, and if this is the case then some burning of the fluid may be evident. Another possibility is that the valve block is sticking and this again should be looked into.
The ECO mode I presume you are referring to is the torque converter type lockup on some automatic transmissions – as your gearbox does employ a locking torque converter in normal driving, then this would not be applicable. One of the advantages of this type of transmission as with the DSG and Powershift units is that the direct-drive is expected to give the same fuel economy as the manual gearbox.