Start-Stop question

MOA4B9

Registered User
Hi everyone, 1 week ago I got the A4 Avast and still trying to find out the in and outs. One thing that I don't understand is the logic behind the Start-Stop system and when it is activated. I don't know if it behaves like it should do or is there is a problem with the car. I tried the different drive modes but mostly been using efficiency mode around town in slow moving traffic. Majority of the time the Start-Stop does not come on. On couple of drives it did work and the engine was switching itself off every time I came to a stop. But most times it never comes on. The dashboard shows a crossed out 'A' in a circle next to gear selection. I would have thought that it should always work especially in efficiency mode. Today I tried other drive modes it wasn't working in these either. Do you think there is something wrong with the car?
 

A4AvantBlackEdition

Registered User
Auto start stop doesn activate if for example the inside of the car is colder than the set temp. It keeps or turns the engine back on to warm the interior of the car.
 

MOA4B9

Registered User
So if the temperature is set to Hi then the start -stop will never activate? Maybe that is the reason as most of the time I have heating on Hi. Will test it tomorrow. Surely an engine that runs at 90 degree will not cool down in the 30 seconds that it is switched off for. The heating should not be affected.
 

A4AvantBlackEdition

Registered User
So if the temperature is set to Hi then the start -stop will never activate? Maybe that is the reason as most of the time I have heating on Hi. Will test it tomorrow. Surely an engine that runs at 90 degree will not cool down in the 30 seconds that it is switched off for. The heating should not be affected.
I don’t know exactly how it works but if it’s set to Hi, that certainly has something to do with it.

Perhaps this could shed some light on it.
 

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MOA4B9

Registered User
Seems that the temperature is to do with using A/C and not heating. I don't have a/c switched on. I don't think the other reasons will apply in my case. Will try to experiment tomorrow.
 

A4AvantBlackEdition

Registered User
Seems that the temperature is to do with using A/C and not heating. I don't have a/c switched on. I don't think the other reasons will apply in my case. Will try to experiment tomorrow.
I’m guessing your internal car temperature is never reaching 30+ (Hi) degrees so the start stop won’t activate as the internal temp isn’t that high.
 

A4AvantBlackEdition

Registered User
Seems that the temperature is to do with using A/C and not heating. I don't have a/c switched on. I don't think the other reasons will apply in my case. Will try to experiment tomorrow.

When it says “the A/C system” it doesn’t mean that you have air conditioning on, it’s just referring to the heating/cooling controls.
 

Nham68

Registered User
Can confirm , if you have it on high , start stop won’t work . I found this out when my son has been tampering with the temp in the back seats....
 

cuke2u

Registered User
So if the temperature is set to Hi then the start -stop will never activate? Maybe that is the reason as most of the time I have heating on Hi. Will test it tomorrow. Surely an engine that runs at 90 degree will not cool down in the 30 seconds that it is switched off for. The heating should not be affected.
Yes the climate set to hi will prevent the start/stop from operating, as it will if set too low. I have never felt the need to set the temp to high, it has climate control and will automatically adjust according to the outside and inside temps. If rapid demist or deice is required I set mine to max then turn it back off after the windows are clear.
 

Buck

Registered User
It’s not just the temperature either. It is the current being drawn from the fan; heated rear window etc etc and if this is relatively high then the engine won’t switch off

It is the same in summer when you have the aircon running at quite a low temp co pared to outside, the engine won’t always turn off.

Having said all of this, I normally deactivate the stop start as I’ve experienced it turning the engine off as I come to a stop at a junction meaning I can’t go for a gap as it causes a second or two delay making it unsafe to pull out.
 

cuke2u

Registered User
As has been documented before, placing the stronic into sport mode defeats the start/stop...
 

SMI77

Australia
Yes, nudging the gearlever into 'Sport' is a very handy tool for close 'in traffic' situations, particularly round-abouts.
Mindful that ours is an Aussie Spec., but any aircon 'on' position disengages 'Stop/Start'.
 

Gary_LB

Registered User
As has been documented before, placing the stronic into sport mode defeats the start/stop...

Is that so? I hadn’t noticed as generally I turn start stop off straight away but this was one of my biggest bug bears with bMW. I could never understand why choosing sports plus did not disengage start stop
 

cuke2u

Registered User
Mind you I have stopped doing that as I have learned other tricks to prevent the start/stop from kicking, one is to not apply the brakes harshly when comingup to a roundabout or junction. Another is, when the start/stop has kicked in, to lightly press the throttle pedal making the engine restart again....
 

cuke2u

Registered User
I don't want to deactivate it as I feel it is useful for reducing emissions...
 
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