Audi stop-start facility

[fiddler3]

I am interested in the views of others into the default setting where the engine stops automatically and starts again when clutch is depressed and gear engaged. I switch off this facility as it seems strange to have the starter motor operating so often in heavy traffic. I am also uncertain as to its overall effect on reducing emissions. I welcome comments on this from those who also have this facility and whether or not they favour its use.

Cheers

David

[johnsimcox]

I am interested in the views of others into the default setting where the engine stops automatically and starts again when clutch is depressed and gear engaged. I switch off this facility as it seems strange to have the starter motor operating so often in heavy traffic. I am also uncertain as to its overall effect on reducing emissions. I welcome comments on this from those who also have this facility and whether or not they favour its use.

Cheers

David
Use it all the time and have no problems with it all. In a recent Autocar longterm test, one of the cars they had (think it was a Kia o Hyundai) actually recorded the amount of time the engine was off with Stop/Start system. If I recall correctly over the 12 month period they had the car the engine was off for something close to 24 hours. Think how much fuel you would burn leaving the car to idle for 24 hours and I think it is pretty certain the system is saving both fuel and reducing emissions. Also look at the fuel consumption on the DIS drop as the car is sitting in traffic. Some will say that it burns more fuel to restart the car, but as it only operates when the engine is at a reasonable temperature this is not a real issue. Find it strange driving other cars that do not have it available

[boof]

I'm on my second car with the system.

I was nervous / concerned about it before hand but ended up having no issues at all with the first car (BMW) and so far no problems with the A6 either.

My understanding is that the car systems are designed around the increased duty cycle and that many clever things go in the background to 'park' the engine allowing for minimal fueling on a restart.

All in all I don't even notice it anymore, it's second nature. I'm only reminded of it whe I have passengers who are not used to such a system and get concerned that the engine has suddenly cut out...

I have no science to back up emissions / mpg figures but it seems logical to me that the engine being switched off whilst not in use is far preferable to it being on and burning fuel.

In a few years time we'll all have cylinder deactivation common place as well I imagine!

[harryg]

How does this effect the turbine in the Turbo? this beast is spinning at about 20,000 RPM engine, engine stops and (oil pump is engine driven I take it) no oil feed to compressor/turbine bearings. Imagine busy period and car stopping and starting in heavy traffic how does lubrication feed turbine bearings...........Learned in merchant navy that you never stop a turbo diesel on full load but bring it down slowly to idle before stopping.
I always disable stop start due to this problem.

[Guest 2]

How does this effect the turbine in the Turbo? this beast is spinning at about 20,000 RPM engine, engine stops and (oil pump is engine driven I take it) no oil feed to compressor/turbine bearings. Imagine busy period and car stopping and starting in heavy traffic how does lubrication feed turbine bearings...........Learned in merchant navy that you never stop a turbo diesel on full load but bring it down slowly to idle before stopping.
I always disable stop start due to this problem.

I think the engineers at Audi have took into consideration the turbo and starter and the car probably have fail-safes should the car be stuck in traffic etc and there is constant on and off. If SS was going to cause damage to the turbo then no-one would use SS and wouldn't be invented?

[boof]

I suspect the oil pump is electric. And / or turbos likely water cooled as well?

The problem you describe would also require you to idle the car at the end of a journey to let the turbo cool. Perhaps on a highly modified and high strung performance engine but otherwise that shouldn't be necessary in a modern car.

These were all concerns I had as well but I came to the conclusion :

- The info that's out there on some of the systems answers the questions.

- Ultimately there's no way they'd manufacture a car with that inherent an issue. If I can identify it as a problem then engine engineers who are 1000x smarter than me have fixed it before breakfast.

- Stop / start isn't a binary function. The car will only shut off if any number of parameters are within tolerance. I can well imagine this includes temperature / pressures in the cooling system for the engine and turbo.

Of course the other question you should ask is that if all the turbo etc components have been designed to have a shorter overall lifespan as it's assumed they will not be in service as much due to stop start. Therefore by disabling the system you're causing greater than designed wear. I think I'm joking... :)

[zollaf]

the turbo is fed oil from the engines oil pump which is driven by the engine so indeed when the engine stops oil stops as well. a turbo will spin at speeds in excess of 200,000 rpm ( yes, two hundred thousand) when going flat out. you should indeed let a turbo'd engine idle before shutting it down after using the turbo. in traffic you are not using the turbo so no need to idle as the engine is only really on or just above idle. the problem is not the speed or the turbo though but the heat it generates. if the unit is glowing cherry red and you switch the engine off, the oil in the turbo burns and forms carbon. do this too many times and say goodbye to your bearings. so if you have been ragging it then hit traffic its not good if the ss turns the engine off. but for most everyday driving it won't cause a problem. how many people don't treat a turbo properly anyway and have them blow in 50k miles ?

[ukgroucho]

I can see how S/s works in cities or in a queue on the motorway but it drives me nuts when I drive around the country lanes that surround me. It is a pain in the whatsit when you arrive at a T junction and all is clear so you put your foot down just as the engine stops. I turn it of as a matter of course.. part of my heading out of the driveway ritual.
Plus I do wonder about wear and tear on batteries and starter motors...

[zollaf]

oh man, that must be soooo annoying then in the country. as you say its fine for where it was intended, the city. i wonder how long before accidents are caused by it.

[ukgroucho]

YUP... and it is one of the few "settings" that the car does not remember between start-ups...
It's a lovely (REALLY lovely) car but there are a few technology decisions that Audi made that may not be aligned with the desires of their customers.. I suspect the s/s one may be policy driven from the perspective of gaining specific fuel consumption ratings.

[Kar Krazy]

I had an A3 1.4 TFSi courtesy car with start stop and I turned it off at first until I got used to the car, but tried it out properly later in the day and it behaved really well. It only stopped the engine after I gave it handbrake and neutral and let the clutch up. As I pressed the clutch pedal down ready to select 1st gear, the engine restarted, so it was ready to go when I needed it.

Ukgroucho, it sounds like your start stop is faulty. For a manual gearbox, I would say it shouldn't stop the engine when you have the clutch down and are in gear ready to pull away. If it's an auto, surely it should only stop the engine when you select neutral or park, then restart when you select drive or reverse. If it is stopping the engine when you are in drive, then it sounds like it is faulty. I'd get it checked.

Fiddler3, I started off not trusting the start stop but ended up finding it no trouble at all. I agree with Ukgroucho that it is to help hit targets for emissions and consumption, but it worked in that car. I prefer it to the "Mobility" (ha ha) tyre re-inflation system that cannot cope with a shredded tyre after a blowout, a really dimwitted weight-saving idea.

[Guest 2]

The SS on an auto cuts in when you have firm pressure on the brake pedal when stopped. It can stop in D.

[Kar Krazy]

The SS on an auto cuts in when you have firm pressure on the brake pedal when stopped. It can stop in D.

Ouch, sounds like that bit was designed by a non-driver, like the roads around my part of the country!

Thanks for the quick reply, Chris!

[Guest 2]

Ouch, sounds like that bit was designed by a non-driver, like the roads around my part of the country!

Thanks for the quick reply, Chris!

On the 10 days or so I had a auto C7 with SS, the SS only cut in once, and that was on the 10th day while parking in Audi's car park handing the car back! It's a phaff on an auto, pretty pointless on that gearbox.

[ukgroucho]

Yes... it works well in a manual (like my wifes A1) but is a bit of a nuisance in an auto unless you are in proper stop / start traffic.

[ukgroucho]

On the 10 days or so I had a auto C7 with SS, the SS only cut in once, and that was on the 10th day while parking in Audi's car park handing the car back! It's a phaff on an auto, pretty pointless on that gearbox.

REALLY? I know it will be ambient temperature dependent but my allroad BiTdi will do the s/s thing after 4 or 5 miles.. maybe less.. it is ANNOYINGLY enthusiastic about doing it hence I switch it of as I leave the drive. I'm pretty sure it is working as normal but I am also pretty sure it is configured for city drivers.

[Guest 2]

REALLY? I know it will be ambient temperature dependent but my allroad BiTdi will do the s/s thing after 4 or 5 miles.. maybe less.. it is ANNOYINGLY enthusiastic about doing it hence I switch it of as I leave the drive. I'm pretty sure it is working as normal but I am also pretty sure it is configured for city drivers.

Yep just once in the 10 days, I actually thought it was broken and was going to mention it to the service advisor but I soon found out from ham it's a common things on auto models due to needing good solid pressure on the brake.

I love my A6 in traffic, no stupid clutching then your left leg starts to get numb (maybe that's just me) like in my A3.

Next A3 replacement will be S-Tronic, never got on with the multitronic and would've preferred a manual!

[Kar Krazy]

My father-in-law had a Honda Jazz with the CVT auto box. The few times I drove it I just couldn't wait to get out of the thing, because it did not instill confidence that it would actually go when you gave it some welly. Later, I test-drove an S-tronic A3 and the difference was like night and day. With just the 1.4 engine it actually felt more responsive than the 1.8 manual A3 I had driven half an hour before.

But if it decided to cut the engine just as I gave it the "go" signal, I would be feeling just like you do about it, UKgroucho.

Can you program the DIS to disable the stop start?

[johnsimcox]

Can you program the DIS to disable the stop start?

Short answer is No, but I think some people have looked at whether you can do it via VCDS. At least on the manual you have the option of simply leaving the clutch pedal pressed and it will not activate.

[jk88]

But if it decided to cut the engine just as I gave it the "go" signal, I would be feeling just like you do about it, UKgroucho.

In my opinion the SS works brilliantly in the auto (in my case S-tronic, can't vouch for the multitronic). Come to a halt with just normal brake pressure and the SS kicks in after about 1 sec. But if you reduce the pressure on the pedal ever so slightly after you stop, this tells the SS not to engage. It becomes very intuitive after a few days.

No problem when you give it the "go" signal either, by the time your foot has got off the brake any anywhere near the accelerator pedal, the engine is up and running with 1st or 2nd gear engaged.

[Olio]

Multitronic works exactly the same.

[Kar Krazy]

In my opinion the SS works brilliantly in the auto (in my case S-tronic, can't vouch for the multitronic). Come to a halt with just normal brake pressure and the SS kicks in after about 1 sec. But if you reduce the pressure on the pedal ever so slightly after you stop, this tells the SS not to engage. It becomes very intuitive after a few days.

No problem when you give it the "go" signal either, by the time your foot has got off the brake any anywhere near the accelerator pedal, the engine is up and running with 1st or 2nd gear engaged.

There you go, it sounds like it's a technique thing. Maybe Ukgroucho has a lot of downhill starts and has to give it extra pressure on the brakes to hold it behind the "give way" line, prompting the system to stop the engine. Auto gearbox "creep" can be a boon but it can sometimes be a curse as well.

[Eddo1968]

I'm another owner (with an s-tronic) who has no problem with SS. If I don't want it to engage (rarely) I only press lightly on the brake pedal. It seems to work perfectly for me.

[harryg]

the turbo is fed oil from the engines oil pump which is driven by the engine so indeed when the engine stops oil stops as well. a turbo will spin at speeds in excess of 200,000 rpm ( yes, two hundred thousand) when going flat out. you should indeed let a turbo'd engine idle before shutting it down after using the turbo. in traffic you are not using the turbo so no need to idle as the engine is only really on or just above idle. the problem is not the speed or the turbo though but the heat it generates. if the unit is glowing cherry red and you switch the engine off, the oil in the turbo burns and forms carbon. do this too many times and say goodbye to your bearings. so if you have been ragging it then hit traffic its not good if the ss turns the engine off. but for most everyday driving it won't cause a problem. how many people don't treat a turbo properly anyway and have them blow in 50k miles ?
I forgot to say I work with Aero Gas Turbines and coking is a problem. Coking is when you shut down the Engine and no oil is being pumped (oil pump driven from AGB) the oil lying in pipes near to heat carbonizes. There are recognised procedures to de-coke these lines normally at Exhaust Gas end of engine. Don't know if Audi has procedures for de-coking or even checking these oil lines.

[zollaf]

replace oil feed pipe when replacing turbo :)

[diecastsink]

Just saw the video "Audi driving fast in german motorway": 250 kph and more for a while, then exit and directly to the red lights and SS was stopping the engine... ouch, that's gonna hurt ...