Higher revs, cold engine?

[PTR200Jag]

Just wondered if anyone knows if the xk8 gearbox doesn't change up to fifth \ or fully engage whilst the engine is "cold" .
That is to say at 50 mph if the revs are say 1500 when the engine is hot then prior to full temperature the gearbox holds higher revs . 3/500 more perhaps, until it is up to temperature.
I had a similar situation on an auto v6 engine in a Honda and that was definetly a factory system.

Just slightly concerned if that is not the case !

[mike020150]

Hi, there is a transmission temperature sensor located inside the gearbox (within the internal wiring harness itself) primarily to sense fluid over-heating conditions. As far as I am aware, there is no deliberate restriction on the engagement of 5th gear when cold. However, the ZF box in 4 litre cars is prone to 'hunting' between gears at about 50mph and, under cold conditions, the wider throttle openings necessary are more likely to be interpreted by the transmission controller as requirements for the engagement of 4th rather than 5th gear. If the gearbox oil is known to have been changed every 40k/50k miles, in the absence of any other symptoms, I wouldn't be too concerned. Mike.

[PTR200Jag]

Hi, there is a transmission temperature sensor located inside the gearbox (within the internal wiring harness itself) primarily to sense fluid over-heating conditions. As far as I am aware, there is no deliberate restriction on the engagement of 5th gear when cold. However, the ZF box in 4 litre cars is prone to 'hunting' between gears at about 50mph and, under cold conditions, the wider throttle openings necessary are more likely to be interpreted by the transmission controller as requirements for the engagement of 4th rather than 5th gear. If the gearbox oil is known to have been changed every 40k/50k miles, in the absence of any other symptoms, I wouldn't be too concerned. Mike.

Thanks for the info, the engine seems smooth and no hunting apparent but in any event once the car has warmed properly normal service is resumed. I thought perhaps that the box might have a sensor and kept slightly higher revs to assist warm up.
Not sure if gearbox oil has been changed at all but it is on the to do list !!