Eco Mode - (Stop-Start) Jerking/Jolting/Jumping C250 CDi 2012

[Gazwould]

See this all over .

Audi don't have a service interval for some ZF autos .

Yet if you contact ZF , it does !

 

[gr8pics]

It is definitely worth checking the voltage of both the main battery under the bonnet and the smaller auxiliary battery in the boot.
Both should be at 12.6 volts or higher with the engine off.

It might be worth putting both on charge using a good charger with an AGM option (e.g. CTEK).

Never thought about charging the backu battery, will do. Do you remember if its on the left or right side?

 

[gr8pics]

Just checked the backup battery, it had a resting voltage of 12.74, so that should be normal?
Btw, when starting the car, it still showed 12.74
Starter battery had a resting voltage of 12.3v

 

[gr8pics]

A couple of observations, charged both backup and starter battery, went out for a test, start/stop now works perfect, not a sign og jolting or jerking, did 4 times after each other, BUT, the 5 time, i pressed the brake pedal for almost a minute, and then it kicked again, so now i wonder if it could be as simple as defect starter battery?
Right after turning off the car, the voltage dropped from 12.4 to 12.2 in two minutes, is that a sign the battery should be replaced?
The backup battery however, maintained 12.8v, right after turning off the car, and still 5 mins later.My theory then, is when the battery is freshly charged, it works smooth, but then the current gradually wears off again, so that the power it needs to fire it all up again, is not enough to engage the aux pump (the car do not know that, before the engine halts, only the voltage it gives when engine is running)
Anyone concur?

I was just hoping i didnt have to spend 200£ on a new battery.

 

[steveq]

Auxiliary is also AGM ?

To the best of my knowledge, yes is the answer.
I looked at the small auxiliary battery in the boot of my C Class with Stop/Start and there are electronic gubbins that pretty well completely cover the top of the battery so I can't see if it is AGM.
However, when I looked up a website for a replacement aux battery for my car it showed an AGM battery as correct.

The main battery under the bonnet is definitely AGM.

My CTEK charger has an option to select AGM mode for charging.
I understand that it is recommended to only charge an AGM battery using a battery charger with the AGM option turned on.

 

[steveq]

Right after turning off the car, the voltage dropped from 12.4 to 12.2 in two minutes, is that a sign the battery should be replaced?

To me, yes it does look like the main battery is showing a low voltage and should be replaced.
As I said above, I understand that AGM batteries should only be charged using a charger with an AGM function.

The CTEK charger I have also has a 'Recon' option which is supposed to recondition a battery and give it a new lease of life.
Does your charger have an option like that?

if not, it may be worth getting a charger that has (and an AGM option) -- it will be far cheaper than buying a new battery.
Even if it isn't a miracle cure and you have to buy a new battery anyway, you will have the comfort of knowing that the old battery is beyond resuscitation and you have a good charger in the garage for the next time.

 

[steveq]

Auxiliary is also AGM ?

To the best of my knowledge, yes is the answer.
I looked at the small auxiliary battery in the boot of my C Class with Stop/Start and there are electronic gubbins that pretty well completely cover the top of the battery so I can't see if it is AGM.
However, when I looked up a website for a replacement aux battery for my car it showed an AGM battery as correct.

The main battery under the bonnet is definitely AGM.

My CTEK charger has an option to select AGM mode for charging.
I understand that it is recommended to only charge an AGM battery using a battery charger with the AGM option turned on.

 

[gr8pics]

Problem solved, it was a old exhausted starter battery. It was okay for regular starts, and running, but not enough peak during start to power the aux pump.
Battery replaced, all works normally again (knock on wood)

 

[davidsl500]

Nice to get a conclusion!

 

[Kat]

Mercedes Eco Mode "Sart-Stop" function problem.

I have recently purchased a 2012 C250 Cdi Blue Efficiency with Eco Start-Stop function with the 7-g auto box. While I accept this feature is a bit like "Marmite" and you either like it or not, so its either permanently switched off if you don't like it, or, like me, it's left on when driving in cities/towns. (Personally for me I find when driving in towns or cities where inherently you get a lot of start-stop traffic I think it's a useful feature to have so have it switched on for this type of driving).

My question is, when the system works and all the system parameters have been met and the car comes to a standstill and switches the engine off, when its time to move off again and I release the brake pedal the car "jerks/jolts/jumps" as it re-engages the forward gear, (similar to putting a manual car in gear with the revs at about 800rpm and the clutch half out). It does this whether I use the "Hold" function and gently press the accelerator or, simply hold the car using the brake, when I release the pressure off the brake pedal. I'm getting no fault codes or warnings on the dash when it does this so as far as I'm aware no fault codes are being recorded in the system computer. It's annoying as I thought it should be smoother when releasing the brake pedal. Has anyone else experienced this and, is this common on Mercedes or do I need to get something reset/fixed? For some reason it doesn't do this if I come to a halt, the engine switches off and I select reverse, it then engages reverse gear and starts with no jolting, jumping or jerkiness.

I bought the car from a MB Specialist reseller. The car has a full MB service history and the seller had the ATF changed the week before I picked the car up at a MB main dealership as it was at 70k and needed doing in accordance with MB service schedule. Following the ATF change MB reset the gearbox using their Star machine.

I've not had the car more than a couple of weeks so couldn't say if it has always done this, but since owning it these last two weeks every time it goes into Eco Stop-Start mode it does this. The car is under warranty so if I need to have something changed, repaired etc I'd like to get it done under the sellers warranty.

Has anyone experienced anything similar and has any idea as to what may be the issue. I've been told it could be the Torque Converter, the auxiliary oil pump that keeps the oil circulating in the gearbox when the start-stop function is active and switches the engine off, and it could even be the batteries, both the main and the smaller battery that manages the Start-Stop and Hold functions.

Thank you !!! After searching the Internet, I can finally say I am not crazy. I too, experience this and it can be difficult to explain to people. I actually had the mechanic tell me I am perceiving it that way...really?? I have been driving since I was 15 and I know my cars inside and out. Mine has behaved the way you have described since day one. It too does not do it when start/ stop is turned off. I now always have it off because the jerking forward can be dangerous. My screen has also gone black on 2 occasions. Which they can't explain. Software has been updated and no faults have been detected. The lane assist has also malfunctioned twice. And the motion detection is always crazy, detecting "nothing". To be honest I would return my car if I could. These little annoying things make the car not so enjoyable. I can finally tell my husband it's "not a girl thing"

 

[steveq]

Thank you !!! After searching the Internet, I can finally say I am not crazy. I too, experience this and it can be difficult to explain to people. I actually had the mechanic tell me I am perceiving it that way...really?? I have been driving since I was 15 and I know my cars inside and out. Mine has behaved the way you have described since day one. It too does not do it when start/ stop is turned off. I now always have it off because the jerking forward can be dangerous. My screen has also gone black on 2 occasions. Which they can't explain. Software has been updated and no faults have been detected. The lane assist has also malfunctioned twice. And the motion detection is always crazy, detecting "nothing". To be honest I would return my car if I could. These little annoying things make the car not so enjoyable. I can finally tell my husband it's "not a girl thing"

According to your profile you have a 2021 A Class ?
Bring it back to the supplying dealer and show them the issue occurring.

 

[Kat]

According to your profile you have a 2021 A Class ?
Bring it back to the supplying dealer and show them the issue occurring.

I have. They drive it and say they do not detect what I describe. Taken it back twice. Correction it's 2020, not 2021. Can't seem to edit my vehicle info. Thank you