Have I got the kickdown right?

The Disco has gone back on the road today after a 4 month list of job were completed which included a top end rebuild, now the car is running beautifully but when I took it for a test run soon after a blast to the red line it started misbehaving. It's a 3.9 auto and after exiting a roundabout it revved to 1500 then dropped to tickover then revved to 1500 then dropped to tickover, which is all it would do. I got it back home, put it in neutral or park and it revs to the red line no problem, is this a gearbox problem and if so - any ideas guys.

I've no idea if the kickdown cable would influence this and I'm not sure if it is correctly adjusted. Also I didn't check the oil level in the box since putting it off road so I'm waiting for all to go cold.

Did you run the top end rebuild in? If you drive gently and then accelerate gently like you are just building up road speed does it behave normally then? remember there is no load on an engine that is just "reving on the drive" as it were and can diguise a great many faults.

Cheers, Nick.

It was run in gently and does exactly the same under very light throttle loads. I disconnected the kickdown completely earlier, took it out 1600 revs just feathering the throttle and sit drops back down to kickover then builds up again. I think it now may be electrickery!

Two things , one if you rev it to the reline in park or neutral too much you can damage the tourqe converter. Two check the connections, particuarly to the engine mangament temp sensor for the coolant ,wiggle them around with it running and see if it revs on its own whilst you are doing it.

I had this on my old BMW and it turned out to be that after two new ariflow metres and idle control valve and a lot of wasted cash.

Good luck