RareAir

My now-departed Macan S had this implementation of Hill Hold, complete with the same dashboard light as in the GT4's cluster.

http://www.edmunds.com/porsche/macan...d-feature.html

I don't have a GT4 to test with, but I got very familiar with the feature on the Macan before selling it. Perhaps it's meant only for PDK cars, but may be worth someone here trying out if they haven't already.

Reborn996

The safety issue is that the car as it is now will hold itself for about a second or two and then release without having any indication it is going to do so. Why hold for only a second or two? On steep hills like in SF the hill hold is a great feature to have as without having a manual parking brake to use it can be very challenging to switch from fully braked to clutch release and throttle with a cab parked right on your rear a foot from your bumper (ask how I know). Yes, I do know how to drive a stick... but prefer having this hold work like it did my 991 so I don't have to take risks of too much roll back or smoking my clutch in SF.

Yes you should always have the brake on when on a hill... but the second or two may not always be enough to gradually engage the clutch (without smoking it) and provide enough throttle to overcome gravity on steep hills in stop and go traffic (SF). If your not quick enough the car will roll back in its current config... not good. This really is a feature needed for cities like SF and may not matter to most people who don't encounter those crazy hills with lots of traffic.

This is not PDK only, my 991 manual transmission model had this and it worked perfectly! Its actually much more relevant for manual trans versus PDK.

drdonger

I'd forgo all of this hill assist stuff for an actual manual hand brake.

vantage

If you need it to hold indefinitely, I wonder if manually engaging the parking brake would work, since the system detects when you are trying to take off and disengages. Obviously a less than perfect solution for your desire, but worth a try.

9001rpm

Played with that today.

Put your left foot, put your left foot out, then shake it...

I mean just put the clutch in and blip the throttle. Worked for me both times I tired it.

hccyong

As I mentioned above, there are hardware limitations. Most systems will not able to hold indefinitely. The majority of hill hold systems work this way (release after a couple of seconds). The 991 probably has more expensive brake controls hardware.

You should try the Tesla system that just got released. If you apply additional brake pressure on flat ground, it will hold for you, even on flat ground. That's not exactly new but can be helpful if you want to take a rest while at a traffic light and the ground is very slightly inclined. What I think is new is that it can hold on a downhill as well. And you can disengage it either by depressing the accelerator (the obvious way) or disengage via the brake pedal (the not so obvious way but the safer way if you're on a downhill). Yes, it lights a light too. And yes, it has "expensive" hardware that's shared with the Porsche 918. So my guess is that the 918 will hold indefinitely too, although I've never driven one to see if it lights the lamp

Reborn996

I would find it shocking that hardware is different between models for such a simple feature as this. The electronic parking brake is what is used and is probably the same for all cars in operation. I really think this is a programming issue on the GT4.

KingSize.Hamster

I'm actually a little shocked that some find two seconds to be not enough.

Newer cars have so much bite on the clutch and the engines have so much low end torque that one doesn't really need the e brake on an uphill. I drive on a fair bit of steeper hills on a regular basis, around 15 to 20 degree incline, on my 987.1 car previously with no hill hold. I think I literally put the ebrake on fewer than 3 times a year to prevent the car from rolling at starts. Hong Kong isn't exactly a place with a lot of flat roads. Even on the steeper hills I just let go of the clutch first and quickly swap over the right foot to gas pedal. The clutch is usually fully engaged within a second or two at most. So it's not like i need to ride the clutch either.

This makes me think two seconds is really all that anyone needs from the hill hold function ...

STLPCA

^This.

STLPCA

What is your basis for this assertion? I believe you are incorrect - the main braking system is used as has been previously posted.

RealityGT

I would have to agree with other's and would think that a 2 second hold should be more than enough.

Reborn996

Actually, I do not think it is 2 seconds of hold... it is very brief on my car. Not much time to get clutch engagement and apply throttle to overcome gravity on a slope while not giving too much overcoming the clutch. At least that is my current situation... sounds to me like everyone else is having the hold last much longer but without the light in the dash, which is still different than my car.

I checked on the 981 forum and it seems the standard Cayman behaves like my 991 did... the hold will last and the light in the dash comes on when activated.

I made an assumption about this feature using the electric parking brake since this is when the technology was added to the cars... sorry for any confusion.

hccyong

You might have missed my previous post that this is done using the ABS/ESC module. It uses valves to hold pressure in specific lines, just like it uses the same valves to hold and dump pressure for ABS and ESC. These valves are electronically energized and not intended for continuous duty.

You should get your car checked to make sure that the timing is correct. The software has exit conditions (e.g., enough torque from the engine, forward speed, etc.). Perhaps something is causing your hill hold to exit.

Reborn996

Still doesn't make sense even if using the ABS system since it WILL hold for extended times on the 991 and apparently standard 981 as well as other Porsche models. Why have the GT4 behave differently?

hccyong

The 991 most likely has a different generation/model of hardware. I'm not aware of extended hill hold on the regular 981 as I've not tried it myself on them.