Auto start stalling

[RVC]

Hi all, I have a 2013 MK7 with an intermittent problem, about 1 in 5 auto starts the engine will stall directly after starting, i then have to start with the key, it has 73,000km and is only 4,000km since last services and has a new genuine battery fitter by VW as of two days ago, the problem still remains with the new battery, diagnostics from VW two days ago shows no errors in the system

The auto start stalling sounds almost as if the start motor cranking time is to short and needs an extra 1/2 to 1 second

Has anyone else experienced this, if so is there a fix?

[Guest001]

Turn it off permanently

[Lucas_R]

As mentioned above, turning the stop/start function off will cure the issue, but not fix it as such. There is a little plug on the negative terminal of the battery that you can unplug to disable it (otherwise you can disable it using software like Carista, OBDEleven or VCDS).

I know some people like the stop/start function, but personally I hate it. I just bought a Mk7 GTI a few weeks ago and disabled it before driving away for the first time. I have also disabled it on my Audi for the same reason.

[Trentm]

I just push the button to disable every time I drive, however I do like the idea of having it permanently disabled. I don't like the idea of stop / start driving for engine longevity and wear on components and I'm prepared to put up with an increase in fuel consumption/ emissions at the expense of the stop/stat function.

[Guest001]

Both of you just ask if someone in your area can turn it off for you It only takes 30 secs to do . Im at Maroochydore so a bit far from North Lakes

[DV52]

..............There is a little plug on the negative terminal of the battery that you can unplug to disable it ........
...........I just bought a Mk7 GTI a few weeks ago and disabled it before driving away for the first time. I have also disabled it on my Audi for the same reason.

Lucas: No offense intended, but a point of clarification regrading "the little plug on the negative terminal" technique as a solution to disabling SS.

As I suspect that you already know, that little (2 x pin) plug ostensibly powers the Battery Monitor Control Module which VW otherwise calls J367. And you are correct - the module does indeed piggy-back onto the negative battery terminal and yes pulling the plug will disable SS.

But (and there is always a "but") there are undesirable side effects when using this technique which can best be demonstrated by looking at my very cut-down wiring diagram for a typical MQB platform vehicle:



As you can see - the "little plug" is the 2 x pin connector labelled T2 in my diagram. Notice that it supplies power to J367 and more important for SS technique, notice also that pin #1 on the plug is the LIN communication wire. For others reading this, LIN is an acronym for Local Interconnect Network- it's a low speed, single wire protocol used for data exchange between a LIN master module and up to 16 LIN slave control units. In this case, J367 is a LIN slave for the master module "Data bus diagnostic interface" in my diagram (also designated "J533" in the VW wiring diagrams) and the Voltage Regulator on the Alternator is another LIN slave on this local sub-system.

So, the role of J367 is (as the name implies) to monitor the condition of Battery and as part of this function, the module reads every milli-ampere of electrical current that is either pulled from the battery as electrical load, or is injected into the battery by the alternator (or by an external charger - that's why it is essential when using a charger on cars with J367 fitted to use the special lug for the negative charger lead).

This data stream is sent via the LIN bus to J533 and it is used to calculate the optimal charging profile from the alternator. Other battery variables are also fed into this calculation like the manufacture type of the battery and the rated battery capacity (both of these variables are set in the adaptation channels in J533). In addition, there are other changing variables sent over the LIN bus such as prevailing battery voltage and battery temperature (which is calculated using a map and the ambient temperature).

As stated in VW's Self Study Program on SS: "the data obtained allows the charge regulation as well as the charge voltage to be adapted to the charge and operating state of the battery" at any point in time over the battery life cycle.

Of course, if the "little plug" is disconnected - none of these calculations are possible because the LIN bus is severed and because J367 is disabled. This means (I suspect) that the process for maximizing battery longevity (which is optimized via the alternator charging profile) can not happen.

Now, I hate SS (like you) - but I'm not sure that I would want to interfere with the monitoring and optimization of the battery over it's full life cycle! Far better to defeat SS with a diagnostic cable, or even better to install an auto SS kill switch IMHO. Or, said another way- don't disconnect the "little plug"!!

Don

[Lucas_R]

Don - no offence taken, and I wont argue with your electrical knowledge on these vehicles as you are in another league compared to myself and im sure I can speak on behalf of others on this forum in saying you are most likely in another league compared to most people. I am good with mechanical repairs and modifications, but electrical stuff has never been a strong point for me.

To clarify, have disabled the SS system in both my VAG cars via my Carista dongle/app combo, but I have heard of other people on here using the method of unplugging the connector on the battery on MQB cars - so I was simply trying to give the original poster a quick and free method (although I must admit I wasn't aware of the detail you went into, and knowing this now, it's not something I would recommend).

[Siavash180]

Hi,
I know it’s an old post but I have the exact same problem with my 2013 MK7 and I’ve had no luck finding what is causing it!

I know how to disable the auto stop/start function permanently but was wondering if you had any luck finding what caused it and how to fix it?

Thanks 😊
Sam

[DV52]

Hi,
I know it’s an old post but I have the exact same problem with my 2013 MK7 and I’ve had no luck finding what is causing it!

I know how to disable the auto stop/start function permanently but was wondering if you had any luck finding what caused it and how to fix it?
Thanks 
Sam

Sam: Hi

I readily admit that I might be mis-reading your question and of course, I'm not the OP that started this tread - but the Start Stop (SS) function has been deliberately designed by the good-Burghers in Germany to NOT operate unless the following prerequisites are satisfied:

• The vehicle is stationary (speed = 0km/h).
• The Brake pedal has been pressed
• The steering angle is not too high
• Seat-belt must be fastened
• 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.
• battery voltage must be above a threshold
• no trailer attached
• The diesel particulate filter is not in regeneration mode (diesel engines only).

Please note that these are "AND" conditions - so ALL the conditions above must be satisfied before the SS function will shut-down the engine

AND for the particular question about what is needed specifically for automatic engine switch-off, these are the preconditions:

• The driver is wearing their seat belt.
• The driver door is closed.
• The bonnet is closed.
• The factory-fitted towing bracket is not attached electrically to a trailer.
• A minimum engine temperature has been reached.
• The vehicle has been moved since the engine was last switched off.
• For vehicles with Climatronic:the temperature inside the vehicle is within the pre-set temperature range.
• The defrost function of the air conditioning system is not switched on.
• The charging state of the vehicle battery is sufficient.
• The temperature of the vehicle battery is not too low or too high.
• The vehicle is not on a steep incline.
• For vehicles with an automatic gearbox:the front wheels are not angled too sharply.
• The windscreen heating is not switched on.
• Reverse gear is not engaged.
• The park assist system (Park Assist) system is not active.

When the conditions for automatic engine switch-off are fulfilled as above and only when the vehicle is stationary, the engine can also switch off subsequently:

• When the driver creates the required conditions by performing an action, e.g. by switching off the defrost function.
• If the SS button in the center console is pressed twice.
• When selector lever position P is selected in vehicles with an automatic gearbox.

Everything listed above is described in the owner's manual - but given the myriad points, is it any wonder that the engine isn't shut down by SS on various occasions?


I always disable SS on all my vehicles (I happen to believe that SS is the most dangerous facility in the car). But for these that retain the facility, it can sometimes be amusing (even helpful) to invoke the screen below when the SS-with-Slash symbol appears. The screen is meant to provide the driver with the reason(s) why the car's Energy Management System has decided NOT to shut down the engine.



Notes:

• Notice the person-head on some entries - these are the factors causing SS not to function that are in the driver's control.
• The red circled entry is what happens when the "temperature method" is used to code-out SS using a diagnostic cable (I developed the picture for another purpose)

Don