718 Spyder - Auto Stop/Start duration

[Tony B2]

I don't normally use the Auto Stop/Start function as I am rarely in particularly heavy traffic, but yesterday I got stuck in 30 minutes of stationary/near stationary traffic on the A34.

It seemed pointless to leave the car idling for so long, so I enabled Stop/Start.

Immediately the engine switched off. Fine.

But....within 15 seconds it re-started. Crawling forward a few feet re-set the system and then repeat - immediate "off", restart again no more than 15 seconds later.

So basically pointless.

I guess battery condition might make a difference, but the MF display indicated over 14 volts when running, and over 12 volts when stopped.

Headlights were off, DRLs were on, aircon fan was on lowish setting.

Surely the function should work better than this, with a longer "off" phase?

My M3 has stop/start and in these conditions it would make sense, probably going off at least a minute each time.

[DJMC]

When stop start no longer switches the engine off your battery is shot. You seem near this point.

I kept trickle charging mine but one day there was only enough power to turn the engine over, not to start it. Low loader to Indy for new battery.

That was at the 6yr point.

[LiamH66]

Definitely an area I need to understand better. If I stop my GT4 RS on the footbrake once it's up to temperature, generally stops the engine while I am stationary. If I engage the parking brake, it fires up again immediately, but if I put it in "park", it stays stopped. It has somehow felt more intuitive in my manual gearbox cars, but I'm looking for a routine where stationary traffic doesn't involve the engine running. Pushing the gear lever up to the parking position in traffic feels wrong, but I might need to get used to it.

Liam

[mr pg]

Try applying parking brake and (with pdk in drive) pulling both paddles at the same time which puts it into neutral. Can't remember if this works but worth a try. To engage gear just pull on upshift paddle.

[Tony B2]

DJMC said:

When stop start no longer switches the engine off your battery is shot. You seem near this point.

I kept trickle charging mine but one day there was only enough power to turn the engine over, not to start it. Low loader to Indy for new battery.

That was at the 6yr point.

I did wonder about this - any idea on the Porsche Approved Used Car warranty obligation here? I am still within the 2 year period.

I would have thought that if the MF display is showing >12v with the engine off it should be OK, though?

My MF display has positioned the battery voltage at the bottom of the list, so the decimal part of the voltage is obscured by the speed limit indicator - I will re-order the parameters so that I can read this fully.

[SkinnyPete]

DJMC said:

When stop start no longer switches the engine off your battery is shot. You seem near this point.

I kept trickle charging mine but one day there was only enough power to turn the engine over, not to start it. Low loader to Indy for new battery.

That was at the 6yr point.

I don’t disagree with this, however

A few months ago, I commented that my stop start no longer works and that my battery is 11 years old so there’s no doubt its way out, although no other symptoms to suggest this.

I used a maintenance charger for a few hours and stop start has resumed working all summer.

That was it few months ago, who knows how much longer it will last for but I looked forward to the £500+ replacement fee at OPC…

[Maxym]

In my experience auto stop/start on Porsches is late to start operating and, when it does, is quick to re-start the engine again. This is in comparison with a Golf GTI 7.0 and a 2022 320i.

OP, I doubt you have a problem. My 991.2 does much the same.

[HoneyBadgerUK]

You'll find the engine stays off for quite a while if air con is off. With air con on the engine will restart quite quickly.

I believe that Porsche prioritises occupant comfort and so keeps the aircon blowing even when the engine stops, which draws a lot of power from the battery.

In my gf's Fiesta the engine will stay off for a long time, even with the aircon showing as 'on', but you can feel that next to nothing is coming through the vents.

[DJMC]

Tony B2 said:

I did wonder about this - any idea on the Porsche Approved Used Car warranty obligation here? I am still within the 2 year period.

I would have thought that if the MF display is showing >12v with the engine off it should be OK, though?

My MF display has positioned the battery voltage at the bottom of the list, so the decimal part of the voltage is obscured by the speed limit indicator - I will re-order the parameters so that I can read this fully.

OPC replaced our Macan battery (the one I referred to before was my 981) within the extended used approved warranty period BUT... that's because they thought it was the issue whereas they then found it was the lighting ECU having a constant drain and so replaced that to solve the problem (car dead on drive). They left the new battery in which was a plus as the car was 4 1/2 years old.

In your case, they may refuse if it IS the battery but how old is the car?

[jeebsy]

I always have my air con running and think the longest the engine stays off with auto start-stop is 45 seconds, usually closer to 30 (2018 2.5 GTS). I put a brand new battery in last year just after I bought the car too. I had an Audi TTS before this and it would cut the air con when the engine went off which was super annoying but the engine would stay off a lot longer. My sister has a 2021 X5 and that will sit indefinitely with the engine off but it's probably got multiple batteries.

Edited by jeebsy on Friday 6th September 23:00

[LiamH66]

mr pg said:

Try applying parking brake and (with pdk in drive) pulling both paddles at the same time which puts it into neutral. Can't remember if this works but worth a try. To engage gear just pull on upshift paddle.

Gave that a try, but you need to pull and hold both paddles to keep it in neutral. So I went for the nuclear option, and actually read the manual. Evidently auto stop start, at least on the GT4 RS, is only in Drive, Manual 1 or 2, Neutral, or Park (but only if the driver's door is closed). Unless it's in Park, it will only stay stopped with a foot on the brake pedal.

Going back to the OP, there's a small host of exclusions to Stop/Start functioning. Clearly if the air-con compressor needs to be operating, then the engine has to be running, as that's what drives it. But there's also inclines, engine diagnostics, battery temperature and condition, outside temperature high or low, and stop-go traffic with short stop times that can all contribute to the engine continuing to run. Quite surprised the GT4 RS stops quite as often as it does, but then I laughed a bit when I saw it even had it. The car stuggles to hit 25 mpg, and in urban traffic probably doesn't get much above 20 mpg. Not sure it makes a great deal of difference.

I wouldn't worry too much, but would keep an eye on how well the battery holds charge when the car isn't being used. I generally expect a fortnight without having to think about trickle charging. My old 981 GT4 battery, at 8 years old, I asked the OPC to change during the "big" service earlier this year. They came back and said they'd tested it, there was nothing wrong with it, and they advised against changing it. It suffered a couple of deep discharges that could have caused damage over the years, but it does seem they can survive them. CTEK charger definitely helps both with standard conditioning, and occasional "annual maintenance" charging.

Liam

[Tony B2]

DJMC said:

Tony B2 said:

I did wonder about this - any idea on the Porsche Approved Used Car warranty obligation here? I am still within the 2 year period.

I would have thought that if the MF display is showing >12v with the engine off it should be OK, though?

My MF display has positioned the battery voltage at the bottom of the list, so the decimal part of the voltage is obscured by the speed limit indicator - I will re-order the parameters so that I can read this fully.

OPC replaced our Macan battery (the one I referred to before was my 981) within the extended used approved warranty period BUT... that's because they thought it was the issue whereas they then found it was the lighting ECU having a constant drain and so replaced that to solve the problem (car dead on drive). They left the new battery in which was a plus as the car was 4 1/2 years old.

In your case, they may refuse if it IS the battery but how old is the car?

The car is 3.5 years old, and still well within the 2 year Porsche approved warranty.

I think I will give my OPC a call tomorrow and mention this, as I also have a continuing problem with spurious low tyre pressure warnings (indicating -4psi when the display shows 29/32, instead of the recommended 29/33).

They have been very helpful so far, even though I bought the car from a different OPC.