Start/Stop Problem 2014 E Class

[Dieselman]

Presumably for dehumidification reasons?

BTW, one of the parameters the ECO Stop/Start system uses to decide whether or not to be operative is whether the screen is likely to mist up if the engine is stopped, so it must monitor the humidity level somehow or another and that may explain why turning the A/C off affects it's operation?

I keep my A/c off. The screen stays demisted. My old cars don't have A/C...the screens stay demisted.

I suspect the reason is engine loading and the possibility of the evaporator frost condensing on the windscreen.

 

[cunny678]

I leave mine on auto....I just have the air con off. Only time it's on if it starts to steam up and then it's only on for a few minutes.

 

[Red C220]

I'll tinker around with the A/C this weekend and see if makes any difference.

I admit I just leave the a/c on all the time as I thought the de-humidification didn't work if it was off.

Be interesting to see if it makes any difference.

 

[Red C220]

Went out this morning and turned off the a/c but left the heating set on Auto.

This seems to have made a noticeable difference already, ECO was green most of the morning but I still had the issues with it not going green until the car had been parked up for 5-10 minutes then restarted. After the restart it was green all the way.

 

[Fudger]

Went out this morning and turned off the a/c but left the heating set on Auto.

This seems to have made a noticeable difference already, ECO was green most of the morning but I still had the issues with it not going green until the car had been parked up for 5-10 minutes then restarted. After the restart it was green all the way.

Mine acts exactly the same. I have noticed that during colder periods, because of the increased drain on the battery, the ECO light is more often yellow than green. I also noticed that when it is green and the engine has turned off, it will auto start, when sitting in a queue, after only a minute or two especially if lights, stereo and air con are all on; all as expected so I don't think there is an issue.

 

[Dieselman]

As already said, this is a battery voltage issue.

The ECO symbol on my C-Coupe is green after about 300 metres and the system functions as intended.

 

[Spin_bowler]

As regards MPG, mine is supposed to do 64.2 combined!!!

Yeah, good luck with that. Reverse the first two figures and you'll be doing OK on the combined cycle.

 

[Red C220]

As already said, this is a battery voltage issue.

The ECO symbol on my C-Coupe is green after about 300 metres and the system functions as intended.

So what is the issue with our car that is cleared after a 5-10 minute break and a restart?

Tomorrow I have an early start in Surrey and will be driving to Manchester and back. I won't have the a/c on so it will be interesting to see how long it takes to go green on that journey. I'll keep an eye on it and report back. Fuel consumption will also be interesting as that's a full tank journey.

 

[Red C220]

Mine acts exactly the same. I have noticed that during colder periods, because of the increased drain on the battery, the ECO light is more often yellow than green. I also noticed that when it is green and the engine has turned off, it will auto start, when sitting in a queue, after only a minute or two especially if lights, stereo and air con are all on; all as expected so I don't think there is an issue.

I understand this occurring during colder periods, it makes sense.

What I can't figure out is why our car has behaved this way since the day we got it when the outside temperature had been high teens Celcius.

 

[st13phil]

I experimented with my E63 late last night as I had to collect my wife from her office party

Ambient temperature varied between 5.5c and 6.5c on the outward journey (23 miles), and the car hadn't been run for a week so if the battery voltage was going to be on the low side, it was perfect conditions. With the lights, heating, heated seat, stereo and A/C on the ECO light was amber even after 8-10 miles. Water was at normal operating temperature, but oil temp was still only around 60c. I switched the A/C off and the ECO light instantly turned green, so I turned the A/C on again and the ECO light instantly turned amber again. Throughout the rest of the journey (oil temp hit normal temperature of 80c+ after a further couple of miles) I could toggle ECO Stop/Start on or off at will by selecting the A/C on or off.

This would suggest that it's not a battery voltage matter, but part of the control logic regarding a mixture of external temperature, internal cabin temperature, humidity(?), and whether or not the A/C is switched on or off.

 

[Red C220]

The a/c certainly seems to be playing a major part in this.

Our C Class Estate didn't behave like this at all, the a/c was left on all year round and like DM's the ECO used to go green after a few hundred yards, a/c on or not.

 

[Dieselman]

So what is the issue with our car that is cleared after a 5-10 minute break and a restart?

Tomorrow I have an early start in Surrey and will be driving to Manchester and back. I won't have the a/c on so it will be interesting to see how long it takes to go green on that journey. I'll keep an eye on it and report back. Fuel consumption will also be interesting as that's a full tank journey.

If battery voltage is too low at initial start, the ECO light won't go green for some time, if at all during that journey.

When you stop and restart, the higher battery voltage enabled ECO to go green.

 

[Red C220]

If battery voltage is too low at initial start, the ECO light won't go green for some time, if at all during that journey.

When you stop and restart, the higher battery voltage enabled ECO to go green.

Does that symptom point to a specific issue if it has happened since day 1 of ownership?

Also what happens during a restart cycle that removes the issue and why wouldn't the ECO go green without a restart once the battery level had reached a predetermined point?

 

[Colin_b]

For what its worth, in my C250cdi, aircon inhibits the start/stop to a large degree. Plus there appears to be a degree of randomness - sometimes it works perfectly, and other times in conditions where I can discern no patterns it will refuse to work for at least 50 miles.

Very odd.

 

[modelman093]

For what its worth, in my C250cdi, aircon inhibits the start/stop to a large degree. Plus there appears to be a degree of randomness - sometimes it works perfectly, and other times in conditions where I can discern no patterns it will refuse to work for at least 50 miles.

Very odd.

61 250cdi , a/c always on, virtually instant green ECO from a cold start! Hate it (the eco) with passion and switch it off straight away - when I remember!

 

[Dieselman]

61 250cdi , a/c always on, virtually instant green ECO from a cold start! Hate it (the eco) with passion and switch it off straight away - when I remember!

Why does it bother you, though to be fair, on the 4 cylinder engines it is a bit intrusive as it makes the car judder on stop and start. On 6 cylinder engines, it's almost imperceptible.

 

[cunny678]

Yeah, good luck with that. Reverse the first two figures and you'll be doing OK on the combined cycle.

I realise I won't get that as a combined figure, but had hoped I would get over 50 at a constant 70. Most of my travel is motorway - 1 mile from home to Mway and then 22 miles to office. So I would have thought 50 should be achievable.

Did consider a new A6 before the Merc and they wre getting almost 60. Mog at Mway speeds

 

[Spin_bowler]

I realise I won't get that as a combined figure, but had hoped I would get over 50 at a constant 70. Most of my travel is motorway - 1 mile from home to Mway and then 22 miles to office. So I would have thought 50 should be achievable.

Did consider a new A6 before the Merc and they wre getting almost 60. Mog at Mway speeds

I've only done a couple of long motorway runs in mine. I got it to record just over 51 on 180 miles from Herts to Warrington at a steady 70mph pretty much door to door aside from a couple of 50mph stretches governed by average speed cameras. It had less than 1k on the clock at the time. I'm doing the run again next week so I'll see if I can improve on that now it's got a few more miles
under its belt.

 

[Dieselman]

I realise I won't get that as a combined figure, but had hoped I would get over 50 at a constant 70. Most of my travel is motorway - 1 mile from home to Mway and then 22 miles to office. So I would have thought 50 should be achievable.

Did consider a new A6 before the Merc and they wre getting almost 60. Mog at Mway speeds

At this time of year, with Winter diesel, 50mpg is only just attainable.

I'm going to try a grille block to see if the reduced heat loss and better aerodynamics makes any difference.

I recently managed 35mpg on a non-stop 306 mile, motorway, journey.

Is that about right?

 

[Jonobigblind]

The A/C kills my stop start possibilities in my C250 W205. Not such a bad thing as it can be a little too sensitive off the brake pedal so having the A/C on is a good moderator.

Sometimes knock the A/C off but with the wet weather the windscreen doesn't usually take too long to start misting up.

No skin off my nose really, the MPG figures I've been getting are low-mid 50's on my 2,500 mile engine so happy with that as it's 'running in'