Auto Start Stop "finicky"
Thread Starter
Instructor
Joined: Dec 2018
Posts: 101
Likes: 14
From: San Diego, CA
Auto Start Stop "finicky"
My *** worked well and seemed consistent when the car was new to me about 1 year ago (2012 991 C2S). Now it seems to never engage. I've read the manual thoroughly and understand there are a ton of exceptions that disable ***. The air conditioning seems to be the issue (maybe heat as well, don't recall from my testing). In short, despite the interior and exterior vehicle temperature, and despite the AC being set very low, any use of AC whatsoever disables *** actually engaging. Since I typically don't use the *** feature and always use Sport mode where it is disabled, it could be that my recollection of how easily it functioned is not correct. Has anyone else found that any AC or heat use (despite how hard those systems are actually working) disables ***? Thanks much.
Three Wheelin'
Joined: Aug 2016
Posts: 1,613
Likes: 1,078
From: Southern California
My dash camera has a battery voltage shut off limit you can set. I think I set mine to 12.1V. Once the battery dipped that low, it would turn off the camera. Works fine and my car starts every single time. My voltage once started is 14-14.5. However, my *** stopped working at some point.
It wasnt until I went on a 500 mile drive that it mysterisouly started working again. That made me look at the voltage setting on the dash camera. So I set the cutoff voltage much higher and every since then, my *** works fine.
SO, even though your battery is functioning and starting the car. It might be TOO LOW for *** to work. At least that was my experience with my 19 GTS.
It wasnt until I went on a 500 mile drive that it mysterisouly started working again. That made me look at the voltage setting on the dash camera. So I set the cutoff voltage much higher and every since then, my *** works fine.
SO, even though your battery is functioning and starting the car. It might be TOO LOW for *** to work. At least that was my experience with my 19 GTS.
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Joined: May 2002
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From: North bay area
I should point out that to test it properly you should disconnect it from the car, use an actual test tool (the solar ones where you enter the CCA + type are the most accurate I found). A battery might test OK but hide a problem. Your *** is very sensitive to charge level ;-) Everyone's is !
Really good battery tester link here I had a few testers that flat lied to me. This one seems really good for $50 ! It's cyber monday, get one !
Really good battery tester link here I had a few testers that flat lied to me. This one seems really good for $50 ! It's cyber monday, get one !
Thread Starter
Instructor
Joined: Dec 2018
Posts: 101
Likes: 14
From: San Diego, CA
Thanks all. I thought battery as well. Given it was original and 7 years old, I replaced it with an identically speced AGM without testing it. I do mostly short drives these days < 10 mi, but drive almost every day. Maybe it is not getting fully charged? My in dash meter usually says 12.1 - 12.5 V before starting the car and after sitting. That is definitely not open circuit, obviously. Of course it is around 14.5 V when driving.
Burning Brakes
Joined: Aug 2016
Posts: 1,146
Likes: 57
Thanks all. I thought battery as well. Given it was original and 7 years old, I replaced it with an identically speced AGM without testing it. I do mostly short drives these days < 10 mi, but drive almost every day. Maybe it is not getting fully charged? My in dash meter usually says 12.1 - 12.5 V before starting the car and after sitting. That is definitely not open circuit, obviously. Of course it is around 14.5 V when driving.
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Thread Starter
Instructor
Joined: Dec 2018
Posts: 101
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From: San Diego, CA
Did you have the car recalibrated to a new battery with PIWIS? That is a part of the process & there are ways the car behaves when the voltage is low & when it THINKS the battery is old. There is a process for this recalibration that has been well documented on this site. If I have some time later I will look for it but it absolutely needs to be done.
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Burning Brakes
Joined: Aug 2016
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Likes: 57
It ABSOLUTELY exists as an option within PIWIS II (Ive seen it). To what extent it is NECESSARY? Not sure. There are plenty of threads on this that go as far as pointing out how to do it with aftermarket OBD devices like Creader as well.
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Joined: Jul 2001
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From: Marineland FL
It is amazing how strange things can happen with a weak battery: the security light on my Harley was coming on after a few miles and then turning off after a few more miles and my PC mouse required me to left click to move the mouse after I stopped moving it - new batteries in both corrected the problems.
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Joined: Sep 2006
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From: Alabama
*** is for the benefit of the manufacturer when certifying MPG. They get an overall higher MPG rating to meet standards. Down the road as the battery weakens *** won't work. Same happened on my car. Once I replaced the battery and had the PIWIS tell the computer the type and rating of battery, *** worked great. I expect as time goes on, it won't work again.
I rarely leave *** on as we, the consumers, and not Porsche will have to pay for batteries and starters when they crap out. The manual says that because of ***, a beefier battery and starter (read more expensive) are used and are considered wear items and not covered under warranty.
Bottom line - use ***, pay more and Porsche gets the credit and future money from you. I leave it off unless I am per mileing for fun.
I rarely leave *** on as we, the consumers, and not Porsche will have to pay for batteries and starters when they crap out. The manual says that because of ***, a beefier battery and starter (read more expensive) are used and are considered wear items and not covered under warranty.
Bottom line - use ***, pay more and Porsche gets the credit and future money from you. I leave it off unless I am per mileing for fun.
Three Wheelin'
Joined: Sep 2018
Posts: 1,495
Likes: 553
I ALWAYS select Sport within seconds of starting my car. I can't be convinced that *** intervention doesn't put an extra load on the whole starting system.
Hopefully, since they engineered the running gear to withstand the ***, not having it engaged will give me a better (longer?) life from the related components.
*** works best in hybrids, a real advantage there.
Hopefully, since they engineered the running gear to withstand the ***, not having it engaged will give me a better (longer?) life from the related components.
*** works best in hybrids, a real advantage there.
Thread Starter
Instructor
Joined: Dec 2018
Posts: 101
Likes: 14
From: San Diego, CA
Three Wheelin'
Joined: Aug 2016
Posts: 1,613
Likes: 1,078
From: Southern California
I thought I read it didnt work on 991.2 with the wheel dial???
I believe thats only got cars that have the sport button on the center console.