Re: The city test does include idlomg.

I have a '14 Boxster S. It's the first car I've owned that stops when it stops. That is -- the engine shuts down when the car comes to a stop. Something about fuel economy and global warming.

Though initially annoying, I've learned to live with the feature and even (somewhat) to like it.

But I've recently turned it off (one button -- who's position is remembered when the "key" is removed between drives) because of concern about wear -- wear of the starter and bearing wear with oil pressure at zero (oil film strength aside).

I'd appreciate comments.

Knowledgeable comments preferred; all comments welcome.

Tx.

I assume you have pdk. I think the start/stop function is only with pdk, not with the manual manual. I don't have pdk, but I wondered the same things as you. Especially wear on the starter motor. Sorry I can't offer anything definitive, but my guess is that Porsche (or at least their sales staff) will tell you that everything is hunky-dory. If it were my car, I'd leave it off permanently. What's a few drops of gas, literally, compared to a chance additional wear and reduce life of parts?

Whatever fuel/fuel cost is being saved, having it always active potentially will be more than made up for when the starter "prematurely" wears out, whether brushes, Bendix drive, pinion or flywheel teeth, etc. Even if the starter, etc, is more robustly built, it will last longer without "unnecessarily" being used. Should my car be running on fumes and stuck in traffic, only then it could be useful.

I was somewhere in this jam:
[l3.yimg.com]

Janis, who owned the now-famous Porsche.

Three friends and I had just gotten our Driver's Ed "blue cards" that Friday morning, and it was my 17th birthday. A friend's father drove us up, but we had to walk about the last 8 miles. I remember seeing a car with a Hawaii plate on either Route 17 or the Thruway. We had gotten our tickets at Bleeker Bob's House of Oldies in Manhattan, and mine, which I still have, is number 00083. Number 83, man! 18 bucks for 3 days. Maybe it was Saturday night and I woke up to the see Pete Townsend's guitar flying into the audience. Years later I found out I had slept through Joplin. We participated in the "Fish" cheer and rain chant. Speaking of rain, I slept on/under my Boy Scout sleeping bag and an old shower curtain, but everything was soggy by Saturday. It was the downside of being so near the stage at the bottom of the big hill. I took a now cherished Instamatic photo of Jefferson Airplane playing very early (Sunday?) morning. One friend got sick from the overly chlorinated drinking water and we left Sunday afternoon, missing Hendrix's Monday set. Well, one friend had gotten lost so we didn't see him until about a week later. We got picked up by a different friend's father who was a NYC police lieutenant, and with generous badge flashing was able to get his car right up to what was left of the entrance. The whole thing in retrospect is one of the great benchmarks of my life. Helluva way to spend a birthday, too.

Quite an experience for a (barely) 17 year old.

Well, it ain't much when I think of my dad at 19 years old with machine gun bursts kicking up the sand under his feet as he ran on Omaha Beach.

Regarding the "Fish" cheer, it was quite something hearing over a quarter million people throw the "F-bomb" all at once. And repeating it.



Edited 1 time(s). Last edit at 03/31/2014 06:32PM by Laz. (view changes)

Grant

gee-lenahan-at-gee-mail-dot-com

I feel it's just a lot of extra wear and tear on the starter and other related parts. I have it turned off almost all the time, The only time I find it useful is at boarder crossings. It saves me turning the engine on and off to move forward every few minutes. Once I'm through, it gets turned off again. It just feels and sounds (or doesn't sound) strange in normal every day driving.

I think Porsche just put it there to help it get better fuel economy ratings. It's just one of a number of little savings here and there. I'm glad they saw fit to allow us to disable it.

>> I think Porsche just put it there to help it get better fuel economy ratings

Almost everything on any new car is now influenced by fuel economy. With fleet averages required to be 35.5 mpg by 2016, we'll see more hybrid systems, more aluminum / carbon, more electronic accessories (e.g. water/oil/steering/ compressor), more start stop, and more turbos to optimize every last joule of energy. Of course since Porsche is now owned by VW, they are able to commingle their 'fleet' numbers along with VW's mileage numbers on TDI's etc, thereby avoiding penalties. Not a bad strategy, and another contributing factor to brand consolidation..

(Since they're measured in MPG)

But CO2 and CO emissions measurements do. There are tax incentives for "idle reduction" technologies.

In the 5th paragraph, they claim that about 18% of the city cycle is spent at idle. Porsche had tried to get EPA to allow use of start-stop in the Panamera testing.

[www.caranddriver.com]

The first part of that paragraph also says that EPA tests have shown no improvement in gas mileage with "Econo-Mode" features (button operated) in several makes of cars (BMW M3 and Honda Insight) In the Insight's case, it relaxes throttle response, which should help fuel economy, but people just push the gas pedal harder to get the performance they want.

I don't know exactly how the Sport Mode in my 981 works to sharpen throttle response. I do know that it Sport Mode, idle is raised about 150 RPM. I suspect that at least in part, having the engine idle faster makes the throttle response more immediate.

Can anyone with Sport Chrono check to see what idle speed is with SC engaged? (I'm guessing it would be around 950 RPM)

City cycle

Trip length: 11 miles
Test time: 31 minutes
Number of stops: 23
Time spent idling: approx. 18%
Maximum speed: 56 MPH
Average speed: 20 MPH

With 18% spent idling,it appears that cutting off the engine probably could have a significant impact on the final number.



Edited 1 time(s). Last edit at 03/31/2014 09:05AM by Lawdevil & CURVN8R. (view changes)

That goes along with the article I posted above.

Mike, would you check to see what your idle speed is with engine warmed up and in Sport Plus mode? I was guess it might be around 950 RPM.

I tried it. In normal mode, it idles at about 650. In Sport or Sport Plus, it idles at 800. Does your idle at 950?

Quote
Lawdevil & CURVN8R
I tried it. In normal mode, it idles at about 650. In Sport or Sport Plus, it idles at 800. Does your idle at 950?

Mine, like yours, idles at 650. Sport mode raises the idle to just over 800 (looks like 810). I was just wondering if Sport Plus raised the idle even more. From your obsevation, there's no change in idle speed between Sport and Sport Plus.

often it is able to handle the usage.

There is no appreciable wear as the engine bearing surfaces have plenty of oil, the engine having just been shut off maybe seconds before the (re)start and the oil is warm and the oil passages are full.

While I do not think I'd like this feature -- I'd think it disconcerting to have the engine stop without me turning off the key -- I wouldn't worry about the starter or any engine wear.

it doesn't like to deliver the high currents for the starter too often

would overlook the battery?

IIRC start/stop doesn't happen if the engine is cold so the starter doesn't have to deal with starting a cold engine possibly over and over again. There is also some monitoring of the battery's condition and a low battery will cause the start/stop function to be disabled.

Honestly, I wouldn't worry about start/stop. That said, as I mentioned earlier, I'd probably disable it as being old school the stopping of the engine from no action on my part would be disconcerting. Probably. However, I might get used to it.

it wouldn't surprise me if he is not to worried about the life span of the battery, which IMO will be shortened by very frequent start cycles.

I agree with you about feeling happier by disabling the start/stop, I think I wouldn't use it.

I don't mind it - but I rarely ever use it since it is locked out when the car is set to "sport" - which is the first button I push after starting the car.

The Service Technik book says the starter will tolerate the duty cycles and the battery is now an Absorbed Glass Matt (AGM) type to better cope. From the way its phrased it makes me think the battery is going to have the shortened life.

In my case, the Autostart disable button was the first thing pushed in the dealership, and it'll never be back on. If it helps Porsche with an EPA credit, but I don't want it doing the shutoff.

Now I have discovered something related and useful, though. If it detects you've stalled the car, such as creeping in the driveway to avoid a bump, it will restart the car for you. Now that is useful.

JIm

My wife's Pruis has this feature. After about a week, i never really noticed it anymore. Now, that's different than the great idle of a Porsche, but these systems have been around for long enough that we would have heard of any excessive wear issues, no?

Exactly... funny how people here and everywhere get so torqued up over such a basic, obvious idea. When in urban traffic I'd think it would be essential in reducing pollutants, etc. To take an extreme example, consider how much pollution Mexico City or Mumbai would have reduced if the millions of cars stuck in stopped traffic each day had this feature?