Sometimes my auto gearbox will hold onto gears a lot longer than it would normally, and it actively resists my attempts of changing up manually, this occurs in either of the following two scenarios:
a) If I have been doing highway / freeway speeds (110km/h) for a period of time in excess of 30 minutes, then drop back into stationary or slower traffic (60 - 80km/h).
b) Sit in stationary or near stop start traffic for longer than 15 - 20 minutes.
The only way to recover from this symptom (that I have found to date) is to stop for 15-20 minutes.
The gearbox has been serviced ~ 15,000 km ago, and the Auto specialist shop didn't find any issues mechanically or diagnostically. That service did actually resolve some seemingly unrelated performance issues with the low speed cruising rev stability, but this issue has persisted.
Has anyone else encountered this issue?
I suspect that it is heat related so I am thinking about trying a heavy duty transmission cooler similar to
Universal SuperCooler rated at 29,200 BTU 11"x11"x1-1/2" or
Hi-Tek Automatic Transmission Cooling System 13-1/2"x9"x3-1/2" with 9-1/2" diameter fan
Anyone got any thoughts, suggestions or other recommendations to offer me?
2011 BMW E38 728i
Linear Mode
