Car won't accelerate on motorway past 70mph

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MS9

New Member
Joined
May 2, 2021
Messages
5
Location
Leeds
Car
E220
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
 
Does your mechanic have MB STAR scanner? If not, then the car needs to be taken to an MB specialist.

It could be an issue with the transmission, or with fuelling, or failing sensor, etc.

Has it been serviced regularly? Air and fuel filters replaced as per schedule?
 
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Maybe the previous owner set the speed limiter to 70 or you have done so accidentally :doh:
I was thinking about it, but the car will go past 70mph without a problem when I accelerate from 0. The issue starts on motorways when I drive 70ish for a long time, then it goes 'limp' and it won't accelerate. But again, sometimes it does. Hence, I want to see if others experienced a similar issue.
 
We have a sprinter at work that does this but it also brings the eml on.
It was in Mercedes about 18 months ago and they fixed it, then last week it started doing it again.
I have no idea what they did though.
It's as if it loses boost.
 
We have a sprinter at work that does this but it also brings the eml on.
It was in Mercedes about 18 months ago and they fixed it, then last week it started doing it again.
I have no idea what they did though.
It's as if it loses boost.
Exactly the same issue by the look of it. But it’s not always like that, sometimes it runs fine. I’m looking for decent mechanics around Leeds. Hopefully they can fix it.
 
Our sprinter is the same, will be fine for weeks then suddenly problems.
It will be fine to start with then during the day suddenly it starts playing up.
 
I had a friend who accidentally set his speed limiter and it took me, sorry him, a couple of days to work out what was wrong.

In his defence he never used cruise control or had ever set a speed limit, and the car was new to him and he had been messing about pushing buttons to see what they did. :dk:
 
I had a friend who accidentally set his speed limiter and it took me, sorry him, a couple of days to work out what was wrong.

In his defence he never used cruise control or had ever set a speed limit, and the car was new to him and he had been messing about pushing buttons to see what they did. :dk:
I’m glad you, sorry your friend found the issue.
I just went for a ride, no motorways just local roads, gears were shifting from 2 to 6 constantly and engine management light turned itself off again! 🤷‍♂️
 
I’m glad you, sorry your friend found the issue.
I just went for a ride, no motorways just local roads, gears were shifting from 2 to 6 constantly and engine management light turned itself off
Get your gearbox serviced and checked out. Sounds like a TCU or solenoid problem. TCU is £800 in parts alone and needs coding to the car. You can also get it reconditioned on ebay for £200 plus postage. I would put it on STAR for diagnosis.
 
I've had a very similar problem, twice so far in 3000 miles; feels like limp mode, from what I've read. Both times it has happened within a couple of miles of a cold start, and both times switching off, then restarting, restored normal operation. No (iCarsoft) fault codes, no warning lights. I'm just going to carry on until it starts happening more often, if it does, and see how I get on.
 
I had a friend who accidentally set his speed limiter and it took me, sorry him, a couple of days to work out what was wrong.

In his defence he never used cruise control or had ever set a speed limit, and the car was new to him and he had been messing about pushing buttons to see what they did. :dk:

There's also usually a limiter hidden away in the menus, intended for use when winter tyres are fitted.
 
I’m glad you, sorry your friend found the issue.
I just went for a ride, no motorways just local roads, gears were shifting from 2 to 6 constantly and engine management light turned itself off again! 🤷‍♂️
Are you saying that the transmission will not shift into 7th or just on this journey?
 
There's also usually a limiter hidden away in the menus, intended for use when winter tyres are fitted.

There was on both my last two E Classes.
 
My guess would be a faulty air mass meter.
 

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