P38 auto box problems

I have a problem with my auto box on a 1997 P38 range rover its adding in kick down on its own accord so adds a little rev of about 1,000 every few minutes then when using kick down sometimes it just sticks in one gear, but stop and start and all goes back to normal, if you stay in top on motor way it will not happen.
One dealer say new box other says probably an electrical problem any thoughts?
Gary

hi you did not say if it was diesel or petrol,i do know on the petrol model there is a throttle potentiometer that the gearbox takes a signal from so it knows when to kick down, the throttle cables are connected to a small black box these are adjusteable to copensate for wear and tear and other reasons they have to be set at close to zero no throttle as kickdown only starts at 80% of travel so the book says i will have a read to see how the diesel works,can you let us know what fuel it runs on cheers tiga

Hi

Its a diesel one.

Gary

hi i have had a read up basically here goes the kick down is obviously dependant on engine speed road speed and engine torque being used,the gearbox ecu takes this into its calculations and the selects the correct gear up and down shift including in sport mode although economy and sport have different map settings,the kickdown signal angle sensing is taken from the throttle position sensor,which looks as if its built into the throttle itself,does the gearbox react the same in sport and in normal economy mode, when was the last time the gearbox oil and filter was changed. Also the autobox ecu acorrding to the manual have to stay with the car,what they are saying is that the gearbox has adapted to the gearbox ecu and so equally matched nowing what the car and what demands are put on it,you can try another ecu on it from another car as long as part nos are the same and of course are the same engine,the ecus to change from country and vechiles about 3 different types listed,so basically you can just try another ecu and if it works put your old 1 back on and then buy a new one and get it reprogrammed at a specalist car dealer hope this helps i would go for changing the oil and filter first tiga

Hi
Thanks. Have already done gearbox oil and gearbox filter so its got to be the ecu, so will try this and see what happens. Unsure what you mean about reprogramming it? will not a new one just do the trick?
Gary24400

hi gary yes you can fit a new one but the programming is to let the ecu know the engine details also stores your VIN,im sure it would make a difference not having it programmed but from time to time new programmes are available for ecu programming to update or clear certain known faults,what about taking it to a main dealer to get there opinion,i must say since being on this site im appauled by how much main dealers want and they wont even look at your car for nothing our dealership is not like that thank god we are happy to help people and dont rip them off not sure what else to suggest so hard without driving the car and feeling the fault for yourself tiga