Car won't accelerate on motorway past 70mph

[MS9]

Hi there,

This is a strange one, the car drives fine... until I get on the motorway. It will accelerate nicely to 70mph swiftly, but then if I want to take someone over or even when it's up the hill car will not accelerate 80% of the times, it will slowly slow down to about 55mph and then it will pick up again until next hill. My mechanic can't find a problem, hoping you guys can point me in the right direction.

Thanks in advance
E220/2014/2.2

 

[rifiki]

Get the codes read using MB STAR diagnostics before you start throwing money at it.

 

[RhodieBill]

I know a silly question, but you sure you haven't activated the Speed Limiter? (It's part of the Cruise Control)

 

[MS9]

I know a silly question, but you sure you haven't activated the Speed Limiter? (It's part of the Cruise Control)

Haha that’s what I thought at first but checked and that’s not the case. If I accelerate from 0 it will go 80/90. The problem starts when I drive 70ish for longer, then and only in about 80% of times it goes ‘limp’

 

[LostKiwi]

Get the codes read on a code reader that can talk to all the modules in your car.
About the cheapest is the Autel AP200 which is phone/dongle based if you want to DIY.

 

[MS9]

Will do, just came back from 30 min ride, no motorways just local roads. Gears were shifting from 2 to 6 constantly and then engine management light turned itself off! But I know, if I go on motorways it will comeback!