# Start/Stop



## aajax26 (Oct 5, 2004)

How many of you turn off the engine at the traffic light?

In the manual it says turning off the engine for stops greater than 4 seconds helps with improved fuel economy. Since our cars are not equipped with start/stop technology, is it still ok to do it?


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## listerone (Jul 21, 2009)

I wouldn't do it.Any $$$ you might save in fuel would probably be more than made up by increased costs for new starters...batteries...various drivetrain components.


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## 62Lincoln (Sep 26, 2004)

listerone said:


> I wouldn't do it.Any $$$ you might save in fuel would probably be more than made up by increased costs for new starters...batteries...various drivetrain components.


x2

The "stop/start" systems in use in Europe and coming to America involve substantially beefed up starters, etc. for this duty.


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## m6pwr (Jan 26, 2008)

Frequency of starts will affect fuel dilution in the engine oil (increases fuel dilution with more frequent starts). Of course so does prolonged idling. Fortunately, diesels can handle more fuel dilution (up to a point) because diesel fuel is diesel fuel OIL. There is a guy on the BITOG oil forum recently with a Priuis using Start/Stop and his used oil analysis showed a lot of fuel dilution. Maybe BMW has figured out a way to get around that. I personally wouldn't use it except on vary long stops - - something like a train crossing, or construction delays, but not at typical stop lights.


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## Snipe656 (Oct 22, 2009)

62Lincoln said:


> x2
> 
> The "stop/start" systems in use in Europe and coming to America involve substantially beefed up starters, etc. for this duty.


They, well the gas cars at least, are also designed better for the task. What I mean by that and had mentioned in another thread is supposedly they determine what cylinder would be the easiest to start the engine with and that is the cylinder the "start" sprays fuel into and triggers the ignition. Since diesels have no spark like that then wonder if their only real solution is a beefed up starter.

I know someone in a relatively old Dodge mini van who for years has turned it off at lights then back on. He does save a decent chunk of fuel but all the crap he does to do it would drive me nuts.


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## Penguin (Aug 31, 2003)

Considering the many problems people have with the BMW charging system giving "excessive discharge" warnings due to difficulty in charging the engine during short trips, I would hate to imagine what would happen with start/stops cycles at stop lights.

Two other points mentioned:

(1) The existing system is probably not designed for such frequent starts and stops, meaning a likely repair/replacement down the road if this is done, and

(2) While it depends on how long you are idling, estimates I have heard are a 4% MPG increase. Hardly worth it, in my opinion, considering the negatives associated with doing this with a system that is not designed for such use. And in clod weather, I have noticed the diesel uses a lot more fuel until it warms-up. Delaying the warm-up by stopping and starting might negate a lot of the potential fuel savings in cold weather, at least during the warm-up phase.

Eventually, more and more cars will have these systems designed-in with appropriately robust parts for such usage. But I wonder how the traffic jams are going to increase? By this I mean, if eventually all vehicles stop and start their engines at stoplights, how many more stalled vehicles are going to be blocking traffic and need to be pushed off the road? Think of a busy street in a major city... what if on any given rush-hour morning in Chicago, 1 in 20,000 vehicles with an automatic stop-start system stalled in stop and go driving and wouldn't start-up? These system had better be extremely reliable!

Here's some busy road with their daily traffic flow:

Los Angeles I-405 382,000 
Atlanta I-75 365,240 
Houston U.S59 338,510 
Chicago I-90 330,067 
Seattle I-5 301,061 
San Francisco I-80 299,000 
New York I-95 295,400 
San Diego I-15 290,000 
Phoenix I-10 288,101 
Miami I-95 288,000 
Washington I-395 280,000 
Dallas-Fort Worth I-35E 267,250 
Riverside-San Bernardino State Road 91 264,000 
Providence I-95 263,500 
Sacramento I-305 249,000 
San Jose U.S. 101 244,000 
Denver I-25 243,333 
Las Vegas I-15 240,585 
Salt Lake City I-15 235,018 
Honolulu H1 229,393 
Tampa-St. Petersburg I-275 228,000 
Baltimore I-695 224,775 
Detroit I-696 222,093 
Boston I-93 219,598 
Minneapolis I-94 211,744 
Austin I-35 210,832


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## chetah45 (Dec 12, 2011)

I have owned and operated diesel powered vehicles(mostly pickups) continuously since 1983 and one thing I have noticed is the older non-common rail or non-HEUI type diesels do not fire up immediately like the older idi diesels do. My D-50 and non-common rail Cummins fired up within half a rev when hitting the starter. The 335D, HEUI Powerstroke, and Common Rail Cummins requires significant more time to fire when needing start. If start-start technology comes to common rail diesels, there is going to have to be changes for an instantaneous start of these vehicles.


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## Flyingman (Sep 13, 2009)

What I have started doing is switching tranny into neutral at stops, and this will also save a bit of fuel.

I tested this out with my Garmin Ecoroute, it measures throttle position and air flow, and you can really see the difference between D and N as well with and with/out A/C.

If your that anal about fuel consumption, should have bought a Jetta!:thumbup:


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## Snipe656 (Oct 22, 2009)

chetah45 said:


> I have owned and operated diesel powered vehicles(mostly pickups) continuously since 1983 and one thing I have noticed is the older non-common rail or non-HEUI type diesels do not fire up immediately like the older idi diesels do. My D-50 and non-common rail Cummins fired up within half a rev when hitting the starter. The 335D, HEUI Powerstroke, and Common Rail Cummins requires significant more time to fire when needing start. If start-start technology comes to common rail diesels, there is going to have to be changes for an instantaneous start of these vehicles.


In europe they have had the start/stop on the diesels for awhile now. I remember reading a review on I think it was a 320d that had it. Would be curious to see how quickly they start back up and perhaps even how they accomplish it if it is very quickly like how these gas cars are.


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## taibanl (Oct 3, 2010)

Snipe656 said:


> In europe they have had the start/stop on the diesels for awhile now. I remember reading a review on I think it was a 320d that had it. Would be curious to see how quickly they start back up and perhaps even how they accomplish it if it is very quickly like how these gas cars are.


1) All 4 cal three series have had it for a few years in europe
2) my 335d has something like "increased capacity electrical system"

I was thinking of coding to try it out.


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## Snipe656 (Oct 22, 2009)

Of "coding" ?


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## aajax26 (Oct 5, 2004)

Flyingman said:


> What I have started doing is switching tranny into neutral at stops, and this will also save a bit of fuel.
> 
> I tested this out with my Garmin Ecoroute, it measures throttle position and air flow, and you can really see the difference between D and N as well with and with/out A/C.
> 
> If your that anal about fuel consumption, should have bought a Jetta!:thumbup:


I think everyone wants to do their bit for the environment. I bought the D to meet one of those criteria + enjoy driving. Looks like it is not a good idea to stop/start the engine. Thanks for the responses.


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## Snipe656 (Oct 22, 2009)

aajax26 said:


> I think everyone wants to do their bit for the environment.


I don't because I actually I want to drive a muscle car with a gas guzzling big block in it to/from work. I think that would have massive amounts of smiles per miles for me.


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## listerone (Jul 21, 2009)

Penguin said:


> Think of a busy street in a major city... what if on any given rush-hour morning in Chicago, 1 in 20,000 vehicles with an automatic stop-start system stalled in stop and go driving and wouldn't start-up? These system had better be extremely reliable!


I'll bet the shirt on my back that the *real* reason for stop/start is to annoy and inconvenience drivers to the point where they decide to commute to work by pogo stick.You *know* that that's the ultimate dream of the "the earth would be so pristine if only everyone would commit suicide" crowd,which are the ones pushing start/stop...both here and in Europe..


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## Snipe656 (Oct 22, 2009)

From the reviews I have read the start/stop features are very fluid in nature and not something most drivers probably would even notice is going on. That is all for gas powered cars though and I can understand how those could start up easily/effortlessly. I do not know how a diesel would do it but I am sure something has been figured out.


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## listerone (Jul 21, 2009)

aajax26 said:


> I think everyone wants to do their bit for the environment.


Scratch me off *that* list,mate.I do more than enough already for the "environment".If you want to see what the environment is all about travel to southern China like I did about a year agn a *crystal clear* day you can barely see your hand in front of your face because of the pollution.Any complaints you have about the environment should be addressed to Beijing...not BMW/Mercedes/VW/Toyota/Honda/Ford/GM Headquarters.


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## Snipe656 (Oct 22, 2009)

listerone said:


> Scratch me off *that* list,mate.I do more than enough already for the "environment".If you want to see what the environment is all about travel to southern China like I did about a year agn a *crystal clear* day you can barely see your hand in front of your face because of the pollution.Any complaints you have about the environment should be addressed to Beijing...not BMW/Mercedes/VW/Toyota/Honda/Ford/GM Headquarters.


In Singapore every time it rains you get this nasty blackish film on things. Rather noticeable when on a sailboat which is primarily white.


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## listerone (Jul 21, 2009)

Snipe656 said:


> In Singapore every time it rains you get this nasty blackish film on things. Rather noticeable when on a sailboat which is primarily white.


I've been to Singapore a couple of times in the last few years and I didn't really notice the air in Singapore itself being that bad.But while traveling by ferry to Bataam Island (about an hour south) I did notice that the air was a bit murky on the water.I suppose it could have been a light sea fog but,I think,it also could have been pollution.I don't think that there's much industry in that neck of the woods (outside of tiny Singapore,that is) but I know that frequent,huge brushfires occur in nearby parts of Malayasia and Indonesia.

Never been on a sailboat...in Singapore or elsewhere.


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## floydarogers (Oct 11, 2010)

Flyingman said:


> What I have started doing is switching tranny into neutral at stops, and this will also save a bit of fuel.


Supposedly (and I believe it to be true), the ZF transmission de-clutches the torque converter when at a stop. No gain by shifting into neutral...


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## Penguin (Aug 31, 2003)

Snipe656 said:


> From the reviews I have read the start/stop features are very fluid in nature and not something most drivers probably would even notice is going on.


I am sure that is true for a new vehicle functioning as designed. My concern is down the road, so to speak, when vehicles with 100,000, 150,000, and 200,000 miles on them are running around with start-stop system on them. I mean we all have seen old, poorly-maintained vehicles which people have trouble starting, but after a few tries get it to running and drive-off. I'm not sure I'd like those vehicles in the rush hour traffic with a start-stop system involved.


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## Snipe656 (Oct 22, 2009)

Those people will bypass it like half the other stuff they bypass to keep the car on the road.


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## Flyingman (Sep 13, 2009)

floydarogers said:


> Supposedly (and I believe it to be true), the ZF transmission de-clutches the torque converter when at a stop. No gain by shifting into neutral...


Floyd, tell that story to the lie detector. The air mass flow drops and the throttle or engine load drops. It is quite noticeable. Ever wonder why when you put your car in gear with the brake on the rear end drops down a bit? That is the torque being sent to the rear wheels which are locked by the brakes. Causes the rear end to drop down ever so slightly.

Try it some time.


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## A8540TDI (Jan 2, 2011)

+1, the torque converter is not decoupled, there is noticeable "pull" while stopped in drive. I too have taken to shifting into neutral at long lights and stalled traffic.


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## floydarogers (Oct 11, 2010)

*Neutral Idle Control*

You guys haven't read enough: google around for "zf 6hp28 neutral idle control".

NEUTRAL IDLE CONTROL (NIC)A contribution to fuel economy is the NIC function duringstandstill of the car and braking. Clutch A is controlled ina slip mode, so the engine does not need to workagainst the converter in stall condition. The controlfunction is defined so the creeping of the car, to what automatic transmission drivers are accustomed to, still exists.

It leaves it about 20% engaged, looks like.


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## Penguin (Aug 31, 2003)

floydarogers said:


> You guys haven't read enough: google around for "zf 6hp28 neutral idle control".
> 
> NEUTRAL IDLE CONTROL (NIC)A contribution to fuel economy is the NIC function duringstandstill of the car and braking. Clutch A is controlled ina slip mode, so the engine does not need to workagainst the converter in stall condition. The controlfunction is defined so the creeping of the car, to what automatic transmission drivers are accustomed to, still exists.
> 
> It leaves it about 20% engaged, looks like.


I wonder if that contributes to the poor off the line characteristics of the transmission, e.g., it tends to want to lunge forward or jump, and it is much more difficult to smoothly modulate when starting, as compared to most non-BMW transmissions.


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## taibanl (Oct 3, 2010)

Snipe656 said:


> Of "coding" ?


Yes. The m3 owners this year got it (disabled by default) an many have take to codin it in different configurations.


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