Manual Vs S-tronic Cruise Control

[JohnM100]

May be, but according to the Audi documentation the normal Cruise Control only uses engine braking.

The documentation may say that but we know of many undocumented features and also documentation errors - just look in the Little Surprises thread.

If it is being used with a manual gearbox you can get more engine braking by staying in a low gear. With an s-tronic gearbox, as I said in my earlier post, it will change up automatically and therefore give less engine braking.

Well it doesn't do that on mine. It will happy change *down* to increase engine braking but mine also uses 'cruise braking' if needed and I'm not the only one with a car that does this. Changing up a gear whilst going downhill would just lead to runaway train syndrome if the brakes aren't applied (regardless of whether applied by the driver or by the car itself).

Personally I don't think that the will be a difference between different models fitted with the same basic cruise control other than between manual gearbox and s-tronic gearbox or the fact that one type of engine may give more braking effect than another.

....but this thread has already shown that there is a difference and that is what we are trying to investigate.

The difference with ACC is that it does most definitely use the braking system to slow the car or actually stop it if necessary no matter which gearbox is fitted. If fact the ACC does seem to work better with the s-tronic that the manual because when it does stop the car in a traffic queue it always selects first gear ready to move away and changes up as necessary depending on the speed of the traffic with the driver having to do anything.

ACC is not at issue here. It's better than normal cruise control; no argument from me there.

ACC will help stop you crashing into the car in front; normal CC won't. Extending that scenario, the question here is what defines whether normal CC set at 50 when going downhill will crash into the car in front at 50 or allow the car to gain speed over the set 50 and do the deed at 60 (or whatever), assuming the hill is steep enough that engine braking is insufficient.

 

[h5djr]

Well in that case perhaps you need to some proper tests between various cars to determine if the actual braking system is being used as some seem to think it is and some think it is not. Just sitting in the car cannot really tell if the brakes are being used for certain unless it is done at night and you can see the brakes lights coming on. Does it differ between the s-tronic being in manual or auto mode? Does it make a difference what gear is selected with a manual gearbox. There are a lot of variables to compare. Perhaps some cars have a different revision of the ECU software to others or even the s-tronic software. What do Audi think should happen. Perhaps a discussion with an Audi Master Technician at a dealers may throw some informed information about what should happen.

For my part I will have a look on ElsaWin and see if it gives any information.

 

[mjcourtney]

Yes easiest way to tell if its braking is to look in the rear view mirror at night for the brake light reflections, you can also tell as the brake pedal is 'primed' as it's braking. Confirmed by the dealer yesterday that manuals do have this feature, but they are unsure which s-tronics also have it.

Moving the lever between M and D makes little difference to the engine braking in the s-tronic. In D it attempts to downshift and provide engine braking but does if far too late to be of any use. In M mode it doesn't down shift at all, so you can quite happily hit 50 with it set to 30.

I would just be interested to know if the 'cruise braking' is an option which can be 'enabled' in VCDS. It clearly doesn't need any additional hardware as it works on the manuals without ACC.

 

[JohnM100]

For my part I will have a look on ElsaWin and see if it gives any information.

That would be very helpful - thank you Dave.

As from post #8, but italicised where relevant

........ (tested at night so I could see the lights come on as well as feel the braking).

John.

 

[Rob2k68]

I'm also interested more so out of curiousity than anything and I'd also change this behaviour in VCDS if possible. Don't think I'd all of a sudden use it more but if a manual box can do it why not an auto?

Also may help better inform future buyers when selecting options if they want cruise braking with S-Tronic looks like they need ACC as well.

 

[h5djr]

As far as I can see there is no mention of normal cruise control in the ElsaWin manual. The fact that when cruise control is aftermarket fitted by companies such as Hazy Days they say that they only use genuine Audi parts and that it has to be coded using VCDS may mean there some different set ups available.

There is also a complete section in the Owner's Manual (p110 in my copy) about Downhill Speed Control with the Automatic Gearbox including a section which says "Downhill speed control is activated on a downhill gradient when the selector lever is in D/S and the driver presses the brake pedal" and also "On vehicles with cruise control system, downhill speed control is activated when you set a cruising speed" It also gives a Warning which reads "The downhill speed control function cannot defy the laws of physics and may therefore not be able to maintain a constant speed in certain circumstances" It gives no idea of what those circumstances might be!

 

[dolo]

My current 2010 A4 with cruise also uses the brakes to keep the speed correct going down the hill. Following this closely as I have a manual S3 with standard cruise on order and I was under the impression it would not use the brakes to slow according to the brochure.
BTW my daughters A1 1.4 does not use the brakes going down hill with cruise On

 

[mjcourtney]

Good info, but I think the down hill speed control in D just means it will downshift to provide some engine braking. Wish it was more explicit about the mechanical braking

 

[h5djr]

Good info, but I think the down hill speed control in D just means it will downshift to provide some engine braking. Wish it was more explicit about the mechanical braking

Even the section in the Owner's Manual about Cruise Control (p97) is still a little vague. It says " The cruise control system allows you to drive at a constant speed of 20 kph or higher. A constant speed is maintained by adjusting the engine power or braking the vehicle accordingly" But does it mean engine power and engine braking or engine power and normal braking. Personally I would read that as meaning it uses the baking system and further on in the warning section it does say "The brake lights come on when the system brakes the vehicles" But no indication if it is different between manual and s-tronic.

 

[Brasso]

A6 manual I had used to keep to the speed down hills with cruse control on regardless of being in a higher gear. Glad I've gone for acc when the s3 stronic arrives.