Strange Gearbox Behaviour 4.8is !!!

[Neil48is]

Right,i've managed to get a few miles on the car since i finished it. One thing i have noticed is that when the gearbox is cold it tends to hold onto 1st gear till approx 3-3.5k Revs and when the box is warm it tends to change up too early. I find the car "bogging" down at low speeds in sharp bends,junctions etc. It never seems to be in the right gear. If i use the car in manual all the gears select just fine. Could this just be down to needing new fluid and filter in the box or is it potentially more serious??!!!!

[Icer006]

I had a similar issue with mine. Transmission mechatronic unit was replaced.

[Neil48is]

That sounds expensive !!!

[Icer006]

When you drive around 45mph, does it feel like it's shifting back and forth between 3rd and 4th gear?

Mine was replaced under warranty, thank goodness. It cost close to $3.5k for the unit and labor. It's not inside the transmission itself.

[Neil48is]

Its hard to explain really,i've been told that the gearbox has a hot and cold program,the cold holds onto first gear for longer ? The bogging down issue just seems more of an inconvenience than anything,the car will shift upto second but then seems to shift up to 3rd too early at too lower revs causing the car to labour quite a lot. I don't seem to have any of the other issues that people on here seem to have, there is no harsh up or downshift between 1st and 2nd and i have no delay going into reverse. The box works fine in sport and manual modes.