[chief1richard]

Took my M2 out today for a spin and it stalled out 4 times while at a light. I have 6500 miles on it and this has never happened before. I ran 2 days at Watkins Glenn last week and car ran fine. I will have to bring it in for service next week and was wondering if having tracked a car if it would affect any warranty work?

[M-Supra]

I'm willing to bet that you did what I did...engaged your "start/stop" function above start button

I was scratching my head wondering what the hell was wrong with my car

[chief1richard]

Originally Posted by M-Supra

I'm willing to bet that you did what I did...engaged your "start/stop" function above start button

I was scratching my head wondering what the hell was wrong with my car

I feel like an idiot. I have never used this function since car was new. A couple of days ago I let my son use my M2, and he must have activated it. Thanks for pointing this out.

[amw896]

lol

[M-Supra]

Originally Posted by chief1richard

I feel like an idiot. I have never used this function since car was new. A couple of days ago I let my son use my M2, and he must have activated it. Thanks for pointing this out.

You think you feel like an idiot? I do most of the work on my car and had just rotated the air in my tires and then the car would stall out EVERYTIME I came to a stop, F' ME!


Figured it out when my foot touched the gas pedal before my finger hit the starter button...she fired right up, dooooh

[tranck]

When I 1st test drove my car about a month back...came to a stop sign ....where I didn't normally slide through...and I'm like...wtf is with this car?

Guy reached over and shut the thing off - all good.

[F87_LCI]

Happened to me too, lol. Have had the car a couple months...turned off ASS first day and forgot about it. Few weeks ago, pull up to a stop light and car "stalls"...was a day after I flashed with BM3 for the first time. I was like..."oh...here we go." Luckily I noticed that the little led light wasn't lit above the start button. Never a bigger "whew!" has been heard.

[stefan]

ah yes the pursuit of emissions reduction at the cost of starter motors.

[Nezil]

It seems to save a reasonable amount of fuel if you're using your car for commuting in stop start traffic in my experience. I don't believe it is solely for emissions, it has to be economy as well.

[cecaa850]

It took me 10 minutes just to find the button to turn it off. DOH!

[McPurrs]

Originally Posted by stefan

ah yes the pursuit of emissions reduction at the cost of starter motors.

The alternator starts the car back up in some models too. Some BMWs have multiple starter motors for this as well. Source : friend who is mechanic at BMW

[AndrewC1989]

Originally Posted by Nezil

It seems to save a reasonable amount of fuel if you're using your car for commuting in stop start traffic in my experience. I don't believe it is solely for emissions, it has to be economy as well.

I was once told that if your car is low on gas and you're trying to make it to a gas station before going bone dry to not to shut the engine off at any point (red light or something) because rather than conserving a bit of fuel, you'd actually be burning more starting it up than if you were to leave it to idle during that brief time.

Not sure if the technology has changed a lot since then or if the guy who told me that was just full of it but I can't help to think along the same lines. It kinda seems like starting and stopping the car over and over isn't actually saving you any gas since the car has to rev itself a few hundred revolutions over the idle rpm each time it starts itself.

Maybe in a stand still super heavy traffic jam it would save gas but in normal traffic situations I feel like it wouldn't do anything other than be really a really annoying feature.

[Nezil]

Originally Posted by andrewc89

I was once told that if your car is low on gas and you're trying to make it to a gas station before going bone dry to not to shut the engine off at any point (red light or something) because rather than conserving a bit of fuel, you'd actually be burning more starting it up than if you were to leave it to idle during that brief time.

Not sure if the technology has changed a lot since then or if the guy who told me that was just full of it but I can't help to think along the same lines. It kinda seems like starting and stopping the car over and over isn't actually saving you any gas since the car has to rev itself a few hundred revolutions over the idle rpm each time it starts itself.

Maybe in a stand still super heavy traffic jam it would save gas but in normal traffic situations I feel like it wouldn't do anything other than be really a really annoying feature.

In older cars, mostly those with carburetors, starting the engine did use additional fuel. The situation is very different with modern cars, and features like cylinder deactivation and start stop have only become commonplace in recent years for that reason.

On our newer engines, injectors can be enabled on a per cylinder basis, exhaust and inlet duration can be adjusted independently on a per revolution basis, and spark can be fired for each cylinder independently whenever the DME wants. Start stop depending on the implementation, can prep the engine to restart with minimal fuel usage, and minimal load on the starter motor by stopping the engine at a predetermined crank position, having fuel compressed ready to fire, and then ignite the spark in combination with the starter, for example.

Start stop doesn't work when the engine is cold, or if it's too hot, or if the battery charge state is low. There are a number of conditions that must be meet before it works anyway. I may be unusual on this forum, but I think it's pretty clever, and see no point wasting fuel and polluting the air while sat in a traffic jam.

If I wasn't daily driving my car, I might think differently, but since I am, I leave it on.

[akkando]

Originally Posted by Nezil

In older cars, mostly those with carburetors, starting the engine did use additional fuel. The situation is very different with modern cars, and features like cylinder deactivation and start stop have only become commonplace in recent years for that reason.

On our newer engines, injectors can be enabled on a per cylinder basis, exhaust and inlet duration can be adjusted independently on a per revolution basis, and spark can be fired for each cylinder independently whenever the DME wants. Start stop depending on the implementation, can prep the engine to restart with minimal fuel usage, and minimal load on the starter motor by stopping the engine at a predetermined crank position, having fuel compressed ready to fire, and then ignite the spark in combination with the starter, for example.

Start stop doesn't work when the engine is cold, or if it's too hot, or if the battery charge state is low. There are a number of conditions that must be meet before it works anyway. I may be unusual on this forum, but I think it's pretty clever, and see no point wasting fuel and polluting the air while sat in a traffic jam.

If I wasn't daily driving my car, I might think differently, but since I am, I leave it on.

I get very annoyed with it because I expect the car to be responsive when I hit the gas. I can't use it anyway with the modes I drive it so it's a non factor now that I have gotten to know the car.

[Nezil]

I think it's quite different for 6MT vs DCT. You're used to just press gas and go. Manual isn't like that, it's clutch in, shift to 1st, pull away and go. By the time you've done that, the engine is going, it starts whenever you clutch in, so it's not adding any significant delay.