Mk7 Stop/Start System - Issues and Questions

[jjr]

Start Stop system fault with Golf 7 90TSI DSG hatch

Hello, I am onto my second golf DSG 90TSI so I know the car well. This one has had a weird and dangerous problem since new with the start stop system and I was hoping you can help. I have searched for threads on this and only found ones that say occasionally the car will not switch off when stationary. I know and understand that. This problem is different. What happens is that in one in every 20 stops the engine will try to start but it does not have enough energy to start the car. Sometimes it would just stall and other times it will try to start, not start then try to restart itself multiple times. I took the car to VW at 3000km and they detected an unusually low voltage from the battery so they trickle charged it.
What worries me is that they admitted that the car may not start itself on the application of the gas pedal if the battery is low in voltage. So what happens to all us mk7 owners when all of our batteries start to die down in 3 years? Also when I said "wouldnt my driving over the last 3000km have charged the battery sufficiently from the alternator?" He said no because when the car is driving you are sucking energy out of the battery as you have things switched on. It didn't sound right to me.
The trickle charge from the dealer has not helped.
I cant tell you how many times I have tried to take off at the lights only to have the car stall on me. Then I have to put in park and restart. Meanwhile I get beeped at by angry motorists behind me.
I have tried it on flat, decline and incline starts. it still fails. and I have tried it with autohold on or off and it still stalls.
So with the autohold on, it will fail when you try to accelrate and with the autohold off it will stall when you release the foot break and again when it stalls it will try to restart itself and fail. This usually happens not straight away but after 15+ minutes of driving. Im not sure how I should approach this now as the car is not fit for purpose. I can remember to to turn the stop start off but I worry if my wife hops into it with the kids and tries to accelerate away from an intersection. This is a serious problem as a car is supposed to move when you step on the gas. It could end up as a life threatening situation.
The car is only 2 months old and for the for the first 2 months I turned off the stop start to assist with breaking the car in. Now that the car is run in I dont turn off the stop start button and am horrified to find out that the system is so hit and miss on my car. Id actually prefer it to stall at every stop so the dealer could see it but it only happens after 20 minutes of driving and usually when you really need your car to move for example in traffic. i love the car and its my second mk7 and 8th VW but its really scary in its current state.

[Nauend]

I've driven over 21000 kms in mine, using start/stop all the time, and not experienced this ever. Maybe a fault VW are not fixing for you?

[DV52]

Hello, I am onto my second golf DSG 90TSI so I know the car well...............

jjr: Wow- that seems like a real tricky problem! I've never encountered your particulare problem on my car, but are you aware that the mkVII tells you what's happening with the stop/start function in the "Start-stop system status" screen?

On the Comfortline, this screen appears on the composition media head. In essence, this screen samples various parts of the car and it shows in a series of simple reports why stop/start isn't working. The great thing about this screen is that the reports update in real time as circumstances in the car change.

The "Start-stop system status" screen won't fix your problem, but it may help you to understand what it is that's interfering with the operation of the SS facility. Just as a suggestion, why don't you drive with the screen showing and when the intermittent problem arises, take note of any new reports that appear. Hopefully, this should identify the offending area in the car. Good luck!!

oh.... if you aren't aware of how to access the screen, have a look at the following link:

http://www.vwwatercooled.com/forums/f197/stop-start-not-working-92362-post1041607.html#post1041607

[TDIjeff]

If the alternator is any where as big as the 140amp units in my TDI then any drive in normal temperatures will charge the battery enough to allow " normal" use in under 1 hour. A dead flat batt takes up to 9 hours to fully charge when on a charger that is configured for the exact chemistry of the battery. You have enough hours to indicate a problem with the car AND the dealer !

[BFPO40]

9 months of driving a mk7 and not encountered any issues with start / stop.
I believe the system disables S/S when the battery is low, it should not stop at all.

You appear to have two faults, excessive battery drain and failure of the system to disable S/S under low battery conditions.

You can check the battery level by pressing and holding the 0/0 reset button above the steering wheel / below the MFD.
Hold it until it cycles through to battery level, it will show the % charge.

Personally, the car is a hazard and I would refuse it at the dealer, or at least drop it off, insist that they sort it and demand a loan car.

Good luck in getting it put right, you are definately not experiencing a normal mk7 Golf.

[jjr]

Thanks guys now I know how to articulate the problem better to vw " excessive battery drain and failure of the system to disable S/S under low battery conditions." could be nailing it on the head. I will go back to them. Also mine is the base model, not the comfort/highline so ill see if i can see that data on the display screen. I too have had an identical mk7 model prior for 7 months with no problems on that one. Also when they trickle charged it they did say to monitor it. My problem is that they don't seem to know how to fix it and I wanted to be armed with the right info before returning back. Its a problem that would not show in a short test drive from them but if one of them took the car home etc they would cop the problem.

[Snail Style]

Possible issue with the battery manager/sensor on the battery. Maybe just make sure it is plugged in and the terminals are tight to start off?

[Transporter]

I don't drive the car with the stop start technology, but when you leave the A/C switched "ON" shouldn't that automatically disable SS feature.
For sure it can't be that difficult to test the battery and the starting system.
Here is the hint, when you say it only happens after you drive for 20minutes, why don't you drive for the 20 minutes (warm up the car properly) and then go to the dealer? Let the technician drive your car for the 20minutes.

[Kesh]

Thanks guys now I know how to articulate the problem better to vw " excessive battery drain and failure of the system to disable S/S under low battery conditions." could be nailing it on the head. I will go back to them. Also mine is the base model, not the comfort/highline so ill see if i can see that data on the display screen. I too have had an identical mk7 model prior for 7 months with no problems on that one. Also when they trickle charged it they did say to monitor it. My problem is that they don't seem to know how to fix it and I wanted to be armed with the right info before returning back. Its a problem that would not show in a short test drive from them but if one of them took the car home etc they would cop the problem.

You can access the screen regardless of what Mk7 you own! Best of luck getting it fixed mate, it certainly isn't normal and certainly not acceptable for such a short ownership period.

I highly recommend recording the issue you're having with a camera (better if you have many to show that it's a reoccurring issue), as that will be nothing but solid evidence of the cars problem and there's absolutely no way they can deny it.

Some dealers will try to shift the responsibility to you, so make sure you push hard, and if nothing happens, complain and complain, and try other dealers too!

Given that this is a fairly major fault, I'm sure you will be fine

[jjr]

Thanks for the tips and I will post the outcome.

[flagger]

I don't drive the car with the stop start technology, but when you leave the A/C switched "ON" shouldn't that automatically disable SS feature.

Start/Stop works fine when AC is turned on. When the SS kicks in, the AC compressor will turn off, but the cabin fans will still run to circulate the air. Once the car starts up again, the AC compressor will start up again.

I too have a base 90TSI DSG, and only once has the SS system shown an error and failed to turn off the engine. Not sure why, it just showed an error occurred with the SS system on the LCD screen and in the SS section of the info unit. The next day it started working again, and has been fine for several thousand km's. Never has the engine failed to start up again once the engine has stopped in a SS situation.

As above, the alternator should always be keeping the battery topped up while you drive, provided you are not powering crazy things like a 10000W RMS stereo system.

[Midfielder]

Thnx so much jjr for your post. I am experiencing almost exactly the same problem. My Mk7 90tsi DSG was purchases in Feb an I had Start-stop problems from the beginning. On first memorable occasion I was on slight slope an car rolled back when car wouldn't restart. On another occasion my wife was driving and car wouldn't restart at roundabout. She had to manually restart. I also have experienced embarrassment of failure to restart in busy traffic annoying drivers behind. At first I thought it must be something I'm doing but it's not. Basically I would turn off the stop start with each drive and car otherwise works OK. I haven't experienced problem if the Auto hold is disabled and Stop start ON but rarely drive in this setting. Like you I usually experience the problem after extended driving (eg 20 mins into trip; ?? Worse with air conditioner working hard) and when I took it to VW mechanics last week they didn't reproduce (they appeared to drive for 15km on Odo) and couldn't find anything wrong. I'm really concerned about this problem and really don't know what to do - mechanic said they will email VW headquarters to see if others reporting but seems unaware of this as a common problem. I've wondered about the synthetic oil/mineral oils recall issue experienced in hot climates in 2013 but this apparently doesn't apply to my car. Would've to hear more if u find anything out

[DV52]

Start/Stop works fine when AC is turned on. When the SS kicks in, the AC compressor will turn off, but the cabin fans will still run to circulate the air. Once the car starts up again, the AC compressor will start up again.

flagger: I agree entirely with what you have said, but I think that it's the other way round. My observations of the way SS works is that once the AC compressor is operating (i.e. the set cabin temperature is not yet reached), SS will not turn-off. In a sense, SS is the "slave" of other functions (like AC compressor, seatbelt, steering wheel angle etc), rather than the "master" function.

But as far as kesh's problem is concerned, I agree that studying the discover media screen (watching the SS reports) is a good way to get the required info to resolve the issue. Transporter's suggestion of video-ing the screen shots when the fault occurrs is also worth considering (I think).

[Midfielder]

Folks, I've managed to video the stop start failure - I'm taking video to mechanic tomorrow and will try to reproduce problem while mechanic with me - I'm going to a different dealership who say they've seen similar problems

[flagger]

flagger: I agree entirely with what you have said, but I think that it's the other way round. My observations of the way SS works is that once the AC compressor is operating (i.e. the set cabin temperature is not yet reached), SS will not turn-off. In a sense, SS is the "slave" of other functions (like AC compressor, seatbelt, steering wheel angle etc), rather than the "master" function.

I have the basic aircon setup in my 90tsi, not climate control. I would have assumed that the SS programming would have been the same regardless of the aircon setup, but there you go. No wonder there is some confusion between car owners in regards to how SS works.