ML auto box upshift points changing..

[stuart o]

Recently drove for 100 + miles in almost monsoon conditions from Inverness to Lochgilphead - I noticed after a while that the the auto box wasn't changing down as normal and was staying in a gear higher than normal and wasn't keen to go past 2500 RPM - would the slippery conditions have triggered something in the g/box - it only lasted for approx 5 miles then reverted to normal, roads were awash / flooded at this point. To make matters worse at the time I only had about 20 psi in o/side rear, this was unknown to me at the time - found a nail in tyre later on the journey - car was loaded to the gunnels also, roof box full of golf gear

any genius's on here shed some light on this ??
car is 05 ML 270 W163

 

[JEZ.S320L]

Recently drove for 100 + miles in almost monsoon conditions from Inverness to Lochgilphead - I noticed after a while that the the auto box wasn't changing down as normal and was staying in a gear higher than normal and wasn't keen to go past 2500 RPM - would the slippery conditions have triggered something in the g/box - it only lasted for approx 5 miles then reverted to normal, roads were awash / flooded at this point. To make matters worse at the time I only had about 20 psi in o/side rear, this was unknown to me at the time - found a nail in tyre later on the journey - car was loaded to the gunnels also, roof box full of golf gear

any genius's on here shed some light on this ??
car is 05 ML 270 W163

Certainly not a 'genius'. The gearbox remembers the driving style and so after a period of almost pedestrian motoring, requires a spot of 'spirited' driving to wake it up. Of course, the opposite applies as well.

 

[stuart o]

auto box

Hmmmm - not so sure, would this happen after a period of about 20-30 miles at low spead it was bit disconcerting as it initially struggled to climb some of the hills on the road then it cleared and has been perfect ever since..

 

[psmart]

If you didnt turn off your engine inbetween the fault occuring and it being rectified, then it could just be your MAF (Air Flow Sensor) got water on it. The air scoop/silencer is over the drivers side front wheel, goes into a silencer box, then onto the airfilter, then on to the MAF before entering the Turbo, quite possible water got through in those conditions. If it was something more important, you would have been locked in the gear until you turned the engine off!

 

[JEZ.S320L]

Hmmmm - not so sure, would this happen after a period of about 20-30 miles at low spead it was bit disconcerting as it initially struggled to climb some of the hills on the road then it cleared and has been perfect ever since..

Not sure if it is time or distance-related. All I know is that it does.

You can always try it yourself:

Accelerate to your chosen cruise speed - GENTLY and click on c/c. Brake to a slow speed and select 'resume'. Result? A nice gentle acceleration back to cruise. THEN:
Accelerate FLAT OUT to the chosen cruise speed - repeat as above - BUT hold onto the steering wheel when you 'resume'

 

[stuart o]

auto box

Thanks gents - I will see if there is evidence of staining etc of water attempting to get to air filter and will try the cc method to see how it feels and compare - cheers again..

Stuart