Talbot

On Saturday, while city driving, I had a not-too-pleasant experience with (what I suppose was) the Pre Sense "City" function.

I'm stopped in an intersection, waiting to turn left (under a green light). Oncoming traffic is staggered out just in the way that people love to do around here, making it difficult to turn left.
Anyway, I bided my time, and - since I'm still under 250 miles - I'm cognizant that I don't want to just stuff the accelerator to the floor to cross 2 lanes of traffic. (This is in a downtown section of town, so the speed limit is probably 25/30 here).

Anyway, I find an upcoming hole in the cars and I proceed with a moderately aggressive nudge to the accelerator and WHAM. The car stops like I hit a brick wall. My first, instant reaction was "Aw schiesse, the transmission or engine fell out."
A quick glance down at the VC, and there was a BIG RED "PRESENSE" indicator. Now, I was not exactly left hanging out in the lane for the incoming traffic when I got stopped, but I was not far from it. It was a pretty disturbing incident.

What I do know is: I was not in any collision trajectory by a long shot, AND I did not notice any "pre"-action WARNING to this event.

What I don't know is this:
1) Did I start my maneuver too closely to the passing car (the one I'd be turning BEHIND) and the system though I'd hit that car
or
2) Did the system make a judgement that the 2nd car (the oncoming one) that I was cutting it too closely to go in front of him.

I don't really want to turn safety functions off in my car, but I'm hoping I can tune this one down a little bit.


Maybe Pre Sense is not the correct name of the function that intervened. According to this, it may be "Turn Assist"

https://www.audi-mediacenter.com/en/...e-systems-7184

Johndefiore

I'd really like to know more about Pre-Sense as well. It's not at all clear to me how and when it would make a decision to apply the brakes, and the description in the manual is kind of vague. There's "regular" Pre-Sense and City pre-sense, which is also a bit ambiguous. Maybe someone here who knows the details can enlighten us.

markcincinnati

Count me as a +1 in terms of trying to understand when (and perhaps why) things happen. I have had the Pre Sense triangle illuminate several times, once for a dog that ran in front of the car (I was able to react and not hit the dog). I set one of the settings to "Medium" -- I set another setting that asks for a decision made in "seconds" to 1 second, as I recall, maybe .8. Three seconds was the longest interval allowed.

I have had the REAR cross traffic "assist" give me the "alert jolt" (which would be followed by automatic braking if I ignored the "warning" jolt). Generally speaking, I have found these systems may have saved my butt (or my fender or bumper) perhaps three times in 3,000 miles in somewhat congested circumstances.

A separate manual -- Audi DAP for Dummies -- needs to be available, if you ask me.

superswiss

PreSense intervenes whenever its calculation yield an imminent collision danger. In your case it either thought you were about to hit the car that just passed in front of you or there wasn't enough time to safely cross in front of the oncoming traffic with the moderate amount of throttle you applied and clear all lanes w/o forcing the oncoming drivers to hit the brakes.

The different levels of PreSense monitor different aspects of daily driving. PreSense started out with simple forward collision avoidance. If somebody slammed the brakes in front of you it would warn/intervene. The current system in the B9 with PreSense City also monitors oncoming traffic and intervenes if a collision is imminent when you are turning in front of oncoming traffic. It also intervenes if you are backing out of a parking spot and a car is crossing behind you.

All these safety systems error on the side of safety, so they all have a safety margin that might be higher than want you generally would consider safe. A lot of people in my experience also are very bad at judging the speed of other cars, so while you thought the window was big enough, it really wasn't. Especially since the car read your throttle input and figured you didn't give it enough beans to make it.

Talbot

Thanks for the explanation there. The thing is, I'm 100% sure that I was not in any way at risk for the oncoming car, so I has to be that it thought I jumped the gun on the passing/already passed car.

It just so happens that in this scenario I was paying acute attention to what I was doing because I knew I needed to accommodate the "break-in" mode I've been driving in so far. I even switched to "S" to give me a little more off the line. If I had just been casually driving, maybe I wouldn't be so certain of the conditions. In this case I know exactly what I was doing, and I had already passed on two other situations that were maybe 'too close'.

All of that said, had I been in my old, broken-in S4, I could have made that turn (safely) in all 3 situations without issue.

markcincinnati

At some risk of going down a hole that I've been down before (although I have noticed at least one or two other folks who believe as I do):

"D" is a mode that makes no sense with the 8-speed transmission and the HP and Torque of the current V6T engine.

My feeling is driving in "D" the S4 is always looking to up-shift a bit too early (in the name of fuel economy, I would assume). Something happens in D that I liken to leaving the parking brake on (slightly) inadvertently. The thing just doesn't feel right.

My wife didn't believe me -- she always drover her 2014 SQ5 in D saying that in S it "would never seem to upshift" (which, I'll grant in that implementation of the ZF 8-spd Tiptronic did seem NOT to favor driving in S mode.)

Now, my wife has a 2018 SQ5 and she "can't" make it "feel right" in D mode (I told her so, and on this car I'm right, whew!)

We've been driving our 2018 "S" cars in "S" mode and we've taken to trying something (and we always test theories using "two weekends" as our threshold -- meaning we live with it for 9 days): We set our ADS in "Comfort" for the engine/transmission; upon start up, no matter what mode you're ADS choice is in, it defaults to D, meaning a double pull of the automatic shifter is required to get the thing into S mode.

Previously we had set the engine/transmission to "Dynamic" mode, now that we've changed it we both think the car "appears to be smoother."

I give some credence to this notion, because I changed hers from Dynamic to Comfort without telling her, knowing that she always does the double pull behavior when she gets in the car, assuring the mode is displayed on the center of the screen "S".

After I did the change, I asked her if she noticed anything, and she said "It seems to be just a little bit smoother." She had no idea I had changed the ADS from Dynamic to Comfort. She always puts the car in "S" mode no matter what.

The nine days will be up at the end of the week, or maybe it will be 16 days, it doesn't matter at this point, she loves it.

Of course when I changed mine, the experiment wasn't "blind" since I knew I had changed it. I noticed the car seemed a bit "quieter" which may explain the perception of greater smoothness.

In any case, my recommendation is forget D, drive your S in S.

BTW, if you're wondering, the transmission will still upshift to 8th gear -- so no concerns you'll be driving around at 75MPH in 7th gear burning more fuel than is required.

Talbot

You're preaching to the choir, Pastor Mark. I'm not driving full time in "S" because I'm still breaking it in... 'gently'. It is easier to keep revs below the aforementioned 4K RPM in D.

JD15

Is it possible to completely disable the pre-sense systems and for the car to remember the previous setting when started? I drive in heavy traffic during my commute and I trust myself more than a system with unpredictable behavior.

Glisse

Just need to avoid lugging the engine too much in D mode during the break-in period, which it is very inclined to do.

Glisse

Try changing the traction control to ESC Sport.