Auto speed limiter fault

[MaccaMark]

The feature is certainly flawed and could contribute to an accident or speeding offence. Disappointing implementation by Porsche so turn it off and use the speed limiter in manual mode, when required.

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[MikeMacan4S]

No fabrication here. The improbable scenario I describe happens every time we travel South on the M2. Near to the Gravesend area the Adaptive Limiter switches from 70 to 30 mph and slams on our brakes. No signs are visible at this point.
But you assert that it will never do this - so we must be making it up.
The usage guideline should say that it is dangerous to use this feature.

 

[Wivenhoe]

I think it is strange for you to continue to use it in an area you know it will slam on the brakes. I think the saying “insanity is doing the same thing over and over again expecting a different result” may apply here.

 

[W1NGE]

No fabrication here. The improbable scenario I describe happens every time we travel South on the M2. Near to the Gravesend area the Adaptive Limiter switches from 70 to 30 mph and slams on our brakes. No signs are visible at this point.
But you assert that it will never do this - so we must be making it up.
The usage guideline should say that it is dangerous to use this feature.

When driving without any assistance feature enabled what road sign speed is displayed in the left most tube of the main dashboard - does it change from 70 to 30 when at precisely the same location?

Is there a slip road / local access road / housing adjacent to the exact location where the limit would be 30 mph

 

[MikeMacan4S]

There is no obvious reason for it. I have tried to be helpful by sharing this experience, and to express a view that this is a fault that Porsche should fix. I have nothing more to say about this.

 

[W1NGE]

There is no obvious reason for it. I have tried to be helpful by sharing this experience, and to express a view that this is a fault that Porsche should fix. I have nothing more to say about this.

Fair enough but it isn't a new issue / problem gone undetected as has been mentioned some posts back here and on the Taycan forum.

You've asked a question and we've tried to apply some logic and rationale to what you're experiencing but if you aren't willing to drill down further then so be it.

I experience the drop in speed from 40 to 30 about 300 yards from where I live and it is because the main road runs parallel to a lower speed road by a matter of a few short yards. The camera initially reads the 40 sign but then switches to 30 (unsigned) as I suspect the GPS co-ordinates of the adjacent road overlaps with the main road. 40 is then set again at the next posted sign. My hunch is that this is what you are experiencing.

The implication therefore is that 'intelligent' ACC / speed limiters which rely on both camera and gps data can be fooled and difficult to programmatically workaround. The underlying blame / fault may well be due to inaccurate 3rd party information rather than Porsche specifically.

On the basis most of us are aware of these foibles the preference is to not use any auto mode if only to take away the element of surprise when you least expect it. For this reason I would not waste any money on Porsche InnoDrive or Drive Assist as they all will experience this type of issue at one time or another. Basic cruise control and a manual speed limiter is enough for most and work reliably all of the time. That said there is an option to choose "Using Resume" rather than "Automatic" on the Speed Limit Detection option for both ACC and Limiter which requires human input to make the speed change when one is detected.

 

[MMR]

Fair enough but it isn't a new issue / problem gone undetected as has been mentioned some posts back here and on the Taycan forum.

You've asked a question and we've tried to apply some logic and rationale to what you're experiencing but if you aren't willing to drill down further then so be it.

I experience the drop in speed from 40 to 30 about 300 yards from where I live and it is because the main road runs parallel to a lower speed road by a matter of a few short yards. The camera initially reads the 40 sign but then switches to 30 (unsigned) as I suspect the GPS co-ordinates of the adjacent road overlaps with the main road. 40 is then set again at the next posted sign. My hunch is that this is what you are experiencing.

The implication therefore is that 'intelligent' ACC / speed limiters which rely on both camera and gps data can be fooled and difficult to programmatically workaround. The underlying blame / fault may well be due to inaccurate 3rd party information rather than Porsche specifically.

On the basis most of us are aware of these foibles the preference is to not use any auto mode if only to take away the element of surprise when you least expect it. For this reason I would not waste any money on Porsche InnoDrive or Drive Assist as they all will experience this type of issue at one time or another. Basic cruise control and a manual speed limiter is enough for most and work reliably all of the time. That said there is an option to choose "Using Resume" rather than "Automatic" on the Speed Limit Detection option for both ACC and Limiter which requires human input to make the speed change when one is detected.

Does the RESUME feature turn ACC into regular CC?

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