Cruise control won't select 9th gear...common?

[PaulXC]

As far as I am aware my car hasn't had any software update, but I have always had to Manually Select 9th Gear under 74 MPH!

It has been improving since the first Servicing at 15,500 miles, but I put that down to the Engine "Loosening up" Unless I am on a road that is completely flat or on a slight slope I have to "Paddle" to get 9th at 70MPH and that only happens if the Engine is running fully warm!

Exactly the same with my E220d. Just had it serviced but not noticed it behaving any differently. Will check next time I'm on the M62.

 

[TeddyRuxpin]

Mine had a sw update last April. Still goes into 9th in C & CV.

Your SL400? That's a petrol, unless you have a diesel too?

 

[zipdip]

Well if the op on his journey to work got 9th gear before the update then it must be what MB did to his car,if they are now saying that you can only get 9th gear at 76mph then why have a 9 speed box,I can well understand why he is upset,you buy a car because it will be economical on long runs on low revs in 9 and after a update you are down 5mpg .

 

[markjay]

Seems there are different updates... doing different things.... confusion reigns:

New recall campaign - UPDATE POWERTRAIN CONTROL UNIT SOFTWARE - MBWorld.org Forums

 

[TeddyRuxpin]

From that thread though: "The update just fixes an issue with the Service schedule indicating you need service sooner than you should. It doesn't provide any actual powertrain changes."

 

[sc3992]

My E220D always drops into 9th gear at speeds above 76mph, changing down back to 8th at any speed below 66mph, especially when using Cruise Control.........

 

[Deleted member 126251]

Your SL400? That's a petrol, unless you have a diesel too?

Oops yes you are correct. However a diesel with it's "superior" torque should be able to hold 9th at lower revs compared to a petrol.

However, on the diesels, it might also be something to do with keeping the DPF regen tip top in diesels and a hotter exhaust.

 

[Deleted member 6183]

Perhaps the update is geared towards continental speed limits?

 

[John N]

Hi John, what year is your car, and how long ago did it last go into a MB garage for a service? They probably applied the update without saying anything, they've been rolling out these updates for a while, whenever a car is taken in for a service. That's what they did on my dad's car, for example, they didn't mention it.

Of course, most people don't care, don't notice fuel consumption or RPMs, and have no idea what RPMs their cars should be at for a particular speed... or what gear they're in, in an automatic.[/QUOT

I picked up the car on the 13 March 2019 and the first Servicing was in early December!

 

[TeddyRuxpin]

Cool, so it will already have any updates applied

 

[Mikesmith29]

Mine had a software update last November and another last week.

No real difference on the first one, will have to wait and see for the latest one until next week.

The link above seems to be related to U.S cars.

 

[Petrol Pete]

The OP has taken his diesel car to a Mercedes Benz dealer for a service and an ECU 'upgrade' It comes out'feeling' and driving very different from when he took it in.

He has had it for a few years , they had it for a day.

They Insist they know best. Anyone on here surprised ?...Not me, there will be more of this to come. people like us who join forums tend to be a bit more 'involved' in our cars., my bet is hundreds (if not thousands) of dealer service cars have been 'tweaked' without their owners (drivers) even noticing...or consenting.

 

[Mikesmith29]

It is very much the same with PC's.
Everyone that owns one has it set up and working perfectly, then a software update comes and screws it all up.
Because the software companies know best.

 

[EdMcC]

New member of the forum. Took delivery of a 2020 7000 mile C220D on Friday. Have done 76 miles of.motorway driving so far at 65/70 mph and not once has it gone into 9th. If I manually select it by unshifting the flappy paddle it knocks it back to 8th after a few seconds. On a light throttle at steady speed it should comfortably hold 9th surely?

 

[markjay]

New member of the forum. Took delivery of a 2020 7000 mile C220D on Friday. Have done 76 miles of.motorway driving so far at 65/70 mph and not once has it gone into 9th. If I manually select it by unshifting the flappy paddle it knocks it back to 8th after a few seconds. On a light throttle at steady speed it should comfortably hold 9th surely?

Welcome.

This will depend on how the automatic transmission was programmed from the factory... keeping in mind that in many European countries the speed limit on Motorways is higher than our 70mph.

 

[FiveAlive]

Welcome.

This will depend on how the automatic transmission was programmed from the factory... keeping in mind that in many European countries the speed limit on Motorways is higher than our 70mph.

I think that this is the clux of the issue - the Mercedes engineers either didn't think or didn't care about the UK motorway speed limit. I'm sure that changing to top at 69mph would have been acceptable in the overall balance of emissions/fuel consumption.

It now means either driving in 6th on the motorway, or a cheeky bit of law breaking to get it to change up: once in top, mine is quite happy to stay there when the speed comes back down again.

 

[FiveAlive]

I think that this is the clux of the issue - the Mercedes engineers either didn't think or didn't care about the UK motorway speed limit. I'm sure that changing to top at 69mph would have been acceptable in the overall balance of emissions/fuel consumption.

*crux

 

[markjay]

What's the rpm when you manually shift into 9th at 70mph?

It's worth checking where this rpm sits on the engine's power and torque graphs, perhaps not using 9th gear at 70mph actually makes sense from the design point of view?

 

[Wolfie1]

It may possibly be something to do with performing an auto regen sequence, rpm too low and it wont regen causing dpf issues

 

[OneForTheRoad]

When I get to 70 mph in my e350 I back off the throttle a tiny bit and it enters 9th gear everytime. I also assume the gearbox oil needs to be at a certain temperature from cold for this to happen.