[shivaswrath]

less emission=better for air pollution.

that simple.

[dragonxflare]

I figure if BMW is willing to code the car so people no longer have to press the button to actually turn the ASS off, then it must be a bad thing for the engine. If this was so good, I doubt BMW would be so willing to code it so easily, am I right?

[jdong]

Originally Posted by dragonxflare

I figure if BMW is willing to code the car so people no longer have to press the button to actually turn the ASS off, then it must be a bad thing for the engine. If this was so good, I doubt BMW would be so willing to code it so easily, am I right?

No... I think it's more that BMW is willing to do it because of customer dissatisfaction that can be solved by flipping a bit in the coding. The unrefined shuddering nature of attempting to implement start stop with a plain claw-pole starter rather than using a galvanically isolated switched reluctance ISG that can actually provide the level of refinement one expects out of a luxury car is something I expect from a Kia, not a BMW. Ironically though Kia does use a SR ISG for their start stop. They seem to have grossly overestimated how much tolerance American drivers have for this kind of ownership experience. Sure some owners are fine with the bottom line of saving gas at the cost of their lights dimming and car shuddering at a start. I respect those owners, but would also like to point out that with marginally more expense for a proper 12V starter-alternator, BMW seems like they could have designed a much better micro-hybrid.

[335BBS]

Originally Posted by dragonxflare

Hello all,

I recently purchased a 2013 328i, and I heard that at full stops, the car shuts off to save gas. I always thought that when you turn off a car, then turn on a car, it uses more gas, so why does the auto shut off, "save" gas?

Has BMW changed something with the engine?

Originally Posted by Carnook

I read somewhere that the break even point is four seconds. If the car is off for four seconds than you use less gas than restarting it.

Can't remember where I read that.

Originally Posted by dragonxflare

So it's true? There's no point in using this system?

Originally Posted by SomeRandomer123

I've heard and believe this too.

Originally Posted by Handozizle

This is what i want to know too. I always leave mine on because i get stuck at multiple traffic lights on my daily commute. Seems like it's not good for the alternator but I'm not a BMW engineer..

How could it negatively affect the alternator?

Where do you guys get this stuff?

Originally Posted by rado

Sounds about right to me. Starting a cold engine uses much more fuel, which I think is where some confusion comes in, but cold starts are irrelevant for the ASS function (the engine should still be fully warm for ASS restarts).

Exactly. A cold engine uses more fuel on start up. ASS is instant and saves fuel. Do you really think that virtually every manufacturer in th eworld would implement this system if it didnt save any fuel or caused alternator problems??

[335BBS]

Originally Posted by shivaswrath

less emission=better for air pollution.

that simple.

Good point Shiv.

[Handozizle]

Originally Posted by 335BBS

How could it negatively affect the alternator?

Where do you guys get this stuff?

Well the alternator is what spin/starts the engine right? In my old car, i would start/stop the car once during a one way commute. With this car, it would start and stop anywhere in the 5-10 range for the same commute. I figured it will add more wear in the long run vs. a car without ASS. Again, i'm sure BMW already accounted for this because they have all kind of smart engineers working for them.

[rado]

Originally Posted by Handozizle

Well the alternator is what spin/starts the engine right? In my old car, i would start/stop the car once during a one way commute. With this car, it would start and stop anywhere in the 5-10 range for the same commute. I figured it will add more wear in the long run vs. a car without ASS. Again, i'm sure BMW already accounted for this because they have all kind of smart engineers working for them.

No, the alternator is what generates electricity (using mechanical energy from the engine), the starter motor is what spins and starts the engine. And yes, using the ASS function will add wear to the starter motor, but it's hard to know if it will prove to be significant in the long run.

[335BBS]

Originally Posted by Handozizle

Well the alternator is what spin/starts the engine right? In my old car, i would start/stop the car once during a one way commute. With this car, it would start and stop anywhere in the 5-10 range for the same commute. I figured it will add more wear in the long run vs. a car without ASS. Again, i'm sure BMW already accounted for this because they have all kind of smart engineers working for them.

The alternator charges the battery which cranks the starter. After driving one of those things I don't know how a starter will last on a car driven in stop and go traffic regularly. It doesnt spin much on re-start but it still spins. Instead of twice a day the starter now gets used about 20-30+ on a stop and go commute. I'm sure they have accounted for this......at least up until warranty expires.............

[Cyberdemon]

"I've got an engineering degree from Internet U."

Auto Start Stop has been common in Europe for years. The reality if you ever encounter a traffic light then you are stopping for more than 4 (or whatever X seconds) is and that will conserve gas. Most lights in my area are 30 seconds -2 Minutes long. If you're inching forward in bumper to bumper traffic, then just turn it off.

They allow you to code it to remember it off (it doesn't disable it permanently, simply remembers your last preference) because enough people complained and it was already in the software.

Mechanically, it will increase wear on the starter, but they've mentioned somewhere that the starter is tested to 1 million start/stop cycles, so in reality lots of other parts will probably fail first. (for those of you math inclined, that's ~275 restarts per day, every day for 10 years). How many of you plan on keeping this car for more than 5 years? (I'm looking at you, former E9x owners...)

[jdong]

Originally Posted by rado

No, the alternator is what generates electricity (using mechanical energy from the engine), the starter motor is what spins and starts the engine. And yes, using the ASS function will add wear to the starter motor, but it's hard to know if it will prove to be significant in the long run.

In all honesty I don't blame him for thinking that in 2013, the starter and alternator would be one unit on the belt. Oh well, I guess some things never change

[335BBS]

Originally Posted by jdong

In all honesty I don't blame him for thinking that in 2013, the starter and alternator would be one unit on the belt. Oh well, I guess some things never change

Why would they do that? If one fails they have to replace the entire unit. Doesnt matter that he was confused/didnt know. Now he does. I've learned a lot here.....

[jdong]

Originally Posted by 335BBS

Why would they do that? If one fails they have to replace the entire unit. Doesnt matter that he was confused/didnt know. Now he does. I've learned a lot here.....

It's a waste to have both when an appropriately sized motor-generator can serve both the purpose of a starter and an alternator (an ISG), which is what you find on most mild hybrids. Lately there have been some good ISG offerings that don't require a high-voltage bus. The one that BMW seems to use on the ActiveHybrids on the low-voltage bus is http://www.cpowert.com/products/speedstart.htm. I presume they are using this platform to qualify this platform for a new generation of start-stop.

[335BBS]

Originally Posted by jdong

It's a waste to have both when an appropriately sized motor-generator can serve both the purpose of a starter and an alternator (an ISG), which is what you find on most mild hybrids. Lately there have been some good ISG offerings that don't require a high-voltage bus. The one that BMW seems to use on the ActiveHybrids on the low-voltage bus is http://www.cpowert.com/products/speedstart.htm. I presume they are using this platform to qualify this platform for a new generation of start-stop.

I did not know that....interesting. Thanks.

[Naambezet]

Originally Posted by SamS

If you want a real mind-blower, imagine what it's like when the motor shuts off when you're going 80+mph

Some Audi's do that actually, they disengage the clutch to "sail" when you're backing off the gaspedal.

Originally Posted by rado

No, the alternator is what generates electricity (using mechanical energy from the engine), the starter motor is what spins and starts the engine. And yes, using the ASS function will add wear to the starter motor, but it's hard to know if it will prove to be significant in the long run.

Did you know that BMW vehicles as part of the efficient dynamics program disengage the alternator during acceleration and mostly during cruising, only when the battery needs juice. It engages when backing off the gaspedal. And most vihicles with ASS have more rugged starter motors I've read in some carmagazines.

[SamS]

Originally Posted by Naambezet

Some Audi's do that actually, they disengage the clutch to "sail" when you're backing off the gaspedal.

My car (ActiveHybrid) does it as well, it is awesome. Photo courtesy of forum member Itskoji:

[Bradbury]

I know a guy who manually shut down his engine while at speed to save fuel. He turned the key all the way so he turned off the ignition as well. The steering wheel locked, and as you can imagine, it did not end well. He wasn't hurt, but the car was fucked...

[Jtrevill]

The using more gas to start an engine vs idle is only when you are talking about old carbureted motors. With the newer fuel injection and more so direct injection, the car only gives the exact amount of fuel needed to start, instead of dumping it in as a carburetor would...

[1bad335]

Just bought a 2012 leftover with 0 miles yesterday. 335I sportline. Love it but not feeling the A.S.S. at all. After many questions and much research I found that the MPG savings is almost nothing. The system was designed to save the environment. While I am a fan of saving the environment. The system was just to annoying to me. The starter is not actually used at all but instead the spark plugs are re-fired upon taking off from a stop. My test ride was only about 15 miles so, I will play with it some more when I pick the car up next week. Seems like a good concept but needs tweaking.

[335BBS]

Originally Posted by 1bad335

Just bought a 2012 leftover with 0 miles yesterday. 335I sportline. Love it but not feeling the A.S.S. at all. After many questions and much research I found that the MPG savings is almost nothing. The system was designed to save the environment. While I am a fan of saving the environment. The system was just to annoying to me. The starter is not actually used at all but instead the spark plugs are re-fired upon taking off from a stop. My test ride was only about 15 miles so, I will play with it some more when I pick the car up next week. Seems like a good concept but needs tweaking.

I had a couple of demos for a few days and they had it. I found it neat at first then kind of annoying. I imagine we would all get used to it ...except when trying to turn left QUICKLY from a stop (with engine off).

[jamie335i]

ASS shouldn't be available on a manual car. It is the weirdest thing when it shuts the engine off as the clutch is let out. IMO.

[Elk]

Originally Posted by 335BBS

...except when trying to turn left QUICKLY from a stop (with engine off).

It is trivial. Once the wheel is turned ten degrees or so in preparation for the turn the engine restarts.

[SwampCat84]

The manual says 'may cause excessive wear to certain engine components'... which is reason # 587 why I have it default to "OFF"...

As far as fuel use, its direct injection so it doesnt use an excessive amount to start up the engine again... You do get used to it starting and stopping, but to me its just more annoying...