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Model specific boards => Golf mk7 => Topic started by: Skinnee D on 31 January 2014, 06:07

Title: Auto Stop/Start during warmup
Post by: Skinnee D on 31 January 2014, 06:07
I've been trying to figure out one of the conditions that disables the auto stop/start during engine warmup.

My A/C is switched off (via the illuminated A/C button), but Vehicle Status for auto stop/start with a cold engine still regularly shows a block for some time due to the A/C being required :huh:.

What I found is that reducing the interior temp setting a few degrees (e.g. from 22 to 20) consistently clears the block much quicker, even with the A/C off, so you can get the system working noticeably sooner.

Hopefully you might find this helpful for your daily commute - as I am :smiley:



Title: Re: Auto Stop/Start during warmup
Post by: monkeyhanger on 31 January 2014, 07:56
SkinneeD: Although it says A/C, it'll be the auxillary heater power demand that deactivates your stop-start. Until the engine is warm enough to provide the cabin with its excess heat, the auxillary heater will be required, and by reducing the set temp from 22C to 20C, you have reduced the demand on the heater.
Title: Re: Auto Stop/Start during warmup
Post by: iandjm on 31 January 2014, 08:17
Hi,

Is there an auxillary heater on the Gti too?  I have never known a car warm up as fast as the Gti :)

Ian
Title: Re: Auto Stop/Start during warmup
Post by: Gingernick on 31 January 2014, 08:25
just said that to my wide this morning as I was dropping her off..the car was nearly at full temp after only a few minutes..couldnt believe my eyes!
Title: Re: Auto Stop/Start during warmup
Post by: iandjm on 31 January 2014, 08:47
just said that to my wide this morning as I was dropping her off..the car was nearly at full temp after only a few minutes..couldnt believe my eyes!

There has to be something. Last night at freezing point after driving for 2 minutes I had warm air coming out of the vents and the engine temp had risen to 60 deg!
Title: Re: Auto Stop/Start during warmup
Post by: mistertee on 31 January 2014, 08:48
I found there's a screen on the infortainment that tells you why it hasn't engaged. Usually bizarre stuff like the engine must be runninh??
Title: Re: Auto Stop/Start during warmup
Post by: iandjm on 31 January 2014, 08:49
Or manouvering mode, seatbelt not fastened etc
Title: Re: Auto Stop/Start during warmup
Post by: jivemonkey on 31 January 2014, 08:53
Hi,

Is there an auxillary heater on the Gti too?  I have never known a car warm up as fast as the Gti :)

Ian

The auxiliary heaters have only been fitted to the TDIs, you just may be experiencing better engineering from VW, petrol engines warm up far faster so I'm sure they did something fancy to get heat to the cabin quickly!
Title: Re: Auto Stop/Start during warmup
Post by: Sootchucker on 31 January 2014, 09:03
I've noticed this too. If I've travelled for 5-10 minutes or so, come to a stop, the start / stop may not activate, but if I momentarily turn the heating temperature down from 22°C to say 20°C, the engine will stop and I can then turn the heating back up to 22°C. Strange, the system must be very sensitive.
Title: Re: Auto Stop/Start during warmup
Post by: iandjm on 31 January 2014, 10:12
Hi,

Is there an auxillary heater on the Gti too?  I have never known a car warm up as fast as the Gti :)

Ian

The auxiliary heaters have only been fitted to the TDIs, you just may be experiencing better engineering from VW, petrol engines warm up far faster so I'm sure they did something fancy to get heat to the cabin quickly!

It sure is amazing getting a block that size up to temperature so fast.  My 1.4TSI took 3 or 4 times the time to get warm.  Well done VW  :smiley:
Title: Re: Auto Stop/Start during warmup
Post by: rocknob on 31 January 2014, 10:57
Is there an auxiliary heater on the Gti too?  I have never known a car warm up as fast as the Gti :)

The GTi has feature called Innovative Thermal Management which is basically an electronically controlled thermostat which amongst other things makes it warm up very quickly. The system is designed that when the car is cold the water only circulates through the engine. Once the engine is warm it opens the heater matrix for heating the inside of the car and then only does it open the radiator.

It also cools the turbo when you turn the car off.
Title: Re: Auto Stop/Start during warmup
Post by: iandjm on 31 January 2014, 11:04
Now that is clever  :grin:

Many thanks

Ian
Title: Re: Auto Stop/Start during warmup
Post by: rocknob on 31 January 2014, 11:05
I've been trying to figure out one of the conditions that disables the auto stop/start during engine warmup.

The conditions for the Stop/Start to work are as follows.
The vehicle is stationary (speed = 0km/h).
The engine speed is below 1200rpm
The coolant temperature is between 25°C and 100°C.
The brake vacuum is more than 550mbar
The energy required to restart the engine that was calculated before “engine off” can be supplied
by the battery (starting voltage prediction).
The battery temperature is greater or equal to -1°C and less than 55°C.
The air-conditioning requirement of the occupants is not too high.
The difference between target and actual vent temperature is below 8°C.
The diesel particulate filter is not in regeneration mode (diesel engines only).
Title: Re: Auto Stop/Start during warmup
Post by: jivemonkey on 31 January 2014, 11:08
Is there an auxiliary heater on the Gti too?  I have never known a car warm up as fast as the Gti :)

The GTi has feature called Innovative Thermal Management which is basically an electronically controlled thermostat which amongst other things makes it warm up very quickly. The system is designed that when the car is cold the water only circulates through the engine. Once the engine is warm it opens the heater matrix for heating the inside of the car and then only does it open the radiator.

It also cools the turbo when you turn the car off.

That's going to be a bugger if the actuator fails on the radiator circuit  :undecided:
Title: Re: Auto Stop/Start during warmup
Post by: corgi on 31 January 2014, 11:18
Is there an auxiliary heater on the Gti too?  I have never known a car warm up as fast as the Gti :)

The GTi has feature called Innovative Thermal Management which is basically an electronically controlled thermostat which amongst other things makes it warm up very quickly. The system is designed that when the car is cold the water only circulates through the engine. Once the engine is warm it opens the heater matrix for heating the inside of the car and then only does it open the radiator.

It also cools the turbo when you turn the car off.

That's going to be a bugger if the actuator fails on the radiator circuit  :undecided:

This is the way cars have worked for years with a standard "mechanical" based thermostat. When cold the heater/radiator circuit is blocked by the thermostat until the temperature when the thermostat opens... so the system on the Golf is a little more selective but no much...
Title: Re: Auto Stop/Start during warmup
Post by: iandjm on 31 January 2014, 11:20
Yep it's very clever splitting the block and cylinder head circuits:

http://www.audi.com/com/brand/en/models/efficiency/efficiency_technologies/energy_management/thermal_management.html



Title: Re: Auto Stop/Start during warmup
Post by: Gingernick on 31 January 2014, 11:47
nice vid...it really is noticeably different from the last car..warm air and warm engine in what seemed like just a few minutes
Title: Re: Auto Stop/Start during warmup
Post by: rocknob on 31 January 2014, 11:49
Is there an auxiliary heater on the Gti too?  I have never known a car warm up as fast as the Gti :)

The GTi has feature called Innovative Thermal Management which is basically an electronically controlled thermostat which amongst other things makes it warm up very quickly. The system is designed that when the car is cold the water only circulates through the engine. Once the engine is warm it opens the heater matrix for heating the inside of the car and then only does it open the radiator.

It also cools the turbo when you turn the car off.

That's going to be a bugger if the actuator fails on the radiator circuit  :undecided:

There is an emergency "pop off valve" built in if the thermostat fails.
Title: Re: Auto Stop/Start during warmup
Post by: CraigW on 31 January 2014, 13:43
Ive noticed recently that me stop/start has not been activating even on occasions when its been above 8 degrees (very rare occurence in Scotland  :grin:). The message im constantly getting back is high consumption of energy but the heating is sitting at about 20 degrees usually. I have the climate control sitting on auto and dont know if this is causing the issue.

Also does the stop/start work when your in eco mode? 
Title: Re: Auto Stop/Start during warmup
Post by: jivemonkey on 31 January 2014, 14:01
Ive noticed recently that me stop/start has not been activating even on occasions when its been above 8 degrees (very rare occurence in Scotland  :grin:). The message im constantly getting back is high consumption of energy but the heating is sitting at about 20 degrees usually. I have the climate control sitting on auto and dont know if this is causing the issue.

Also does the stop/start work when your in eco mode?

Interesting! When trying out a recent VCDS tweak to disable the start stop I always had this message on in the Start Stop status menu, it was the minimum/ maximum operating temperature that was changed to achieve it. Hard to believe 8 degrees is too low! I've had it work much lower. Anyway, once I changed it back it functioned fine. Can only assume there's another reason behind the cryptic message which VW don't want you to know..

Start stop works in all driving modes.
Title: Re: Auto Stop/Start during warmup
Post by: corgi on 31 January 2014, 15:24
Also does the stop/start work when your in eco mode?

I would hope it is more likely to work in ECO mode  :smiley:

The high power consumption could be if you're draining significant current from the battery - heated rear window, headlights etc. These stop/start systems are quite careful about making sure the battery will have enough cranking power to restart the engine...
Title: Re: Auto Stop/Start during warmup
Post by: itavaltalainen on 31 January 2014, 17:51

I would hope it is more likely to work in ECO mode  :smiley:
...
These stop/start systems are quite careful about making sure the battery will have enough cranking power to restart the engine...

And yet it is utterly pointless ;)
90% the S/S switches and restarts engine there are only seconds... and when I am actually stationary for longer it would not be difficult to stop/restart it myself...
Title: Re: Auto Stop/Start during warmup
Post by: GolfTi on 31 January 2014, 18:02
It's maybe saved me a litre of fuel in 9k miles...

I am a little concerned about the reduced battery and starter motor life these systems must cause, are they really worth it other than to lower published mpg figures?

I agree with what others have said about warm up times - quite amazing.
Title: Re: Auto Stop/Start during warmup
Post by: dippy_x on 31 January 2014, 19:06
I had a play about with this last week.  I have AC disabled but stop/start doesn't function for a while into the journey - according to the info unit - because of AC.  I have my temps at 23 degrees and fan on two bars.  What I have noticed is if I switch the fan off / no bars the car switches off straight away.
Title: Re: Auto Stop/Start during warmup
Post by: GolfTi on 31 January 2014, 20:02
Didn't VW try a basic stop/start system with the standard mk2/3??

The newer version is a lot more sophisticated but really what is the point?
You save a few quid on fuel but you (or future owner) need a replacement starter/battery sooner than without the system. Is it really a carbon saver?
Title: Re: Auto Stop/Start during warmup
Post by: Skinnee D on 01 February 2014, 06:34
SkinneeD: Although it says A/C, it'll be the auxillary heater power demand that deactivates your stop-start. Until the engine is warm enough to provide the cabin with its excess heat, the auxillary heater will be required, and by reducing the set temp from 22C to 20C, you have reduced the demand on the heater.
MH - I'd thought that too and did have a quick go at deselecting the aux heater but it didn't seem to make any difference - I'll have another look. I do find the feature very handy going to work in the mornings and if a bit of fiddling with settings would get it working earlier that could be good.
The list that rocknob posted earlier includes a <8degC criteria between interior vent and setting temperatures, which would seem to fit with what's happening.