Friday, October 10, 2014

BMW i3 Overactive-Active Cruise Control

When activated, the ACC displays an icon of a car on the road ahead of you. That means you are locked onto a vehicle in your path.
One of the coolest features on the i3 is the Active Cruise Control. The Parking Assistant is cool tech also, but honestly I can't see myself ever using it except to show it off to friends. I can park the car just fine on my own, and faster than the Parking Assistant can. The ACC on the other hand is not only really cool, but very useful.

Whether I'm stuck in slow moving traffic or driving long distance on the highway I'm finding myself using the ACC more and more. It's kind of like locking onto the car in front of you with a tractor beam from some sci-fi show and letting it pull you along. However there is one thing that needs to be improved upon with the i3's ACC. It will occasionally disengage by itself without warning. Yes, it does post a notice on the center display screen that it has deactivated, but unfortunately that is already after it shut off so it's not any real help. In traditionally powered cars, this is less of an issue because the i3 has such strong regenerative braking. When the ACC disengages in a gas car, it will go into a freewheel coast and be barely noticeable, other than the fact that it is gradually slowing down. In the i3, when the ACC disengages the car immediately goes into full regenerative braking mode and abruptly decelerates. It actually quite startling and certainly a safety issue because if someone happens to be tailgating you they could easily run into the back of your car.
The ACC seems to have difficulty driving when you are driving into direct sunlight

Knowing this, many of the existing i3 owners and I are always ready with our foot at the accelerator in case the ACC disengages, so we can quickly restore power to the motor and stop the vehicle from decelerating. It's something that you quickly adjust to, but if you aren't ready for it at the very least it's scary, and at worst a huge safety issue. It seems to happen much more when it's raining, and when the sun is low in the sky and you are driving directly into it. These things must confuse the cameras used for the system. I've also noticed that by driving under some low overpasses the system will shut off on occasion. Perhaps the system gets confused thinking the bridge is an obstruction in the roadway. BMW has advised keeping the windshield clean so the system can see clearly outward, but that is never an issue with me as I always keep my windshield clear.
It was raining when it disengaged this time

I believe the answer to this issue would be for BMW to change the software so the car freewheels like a conventional BMW if the ACC disengages by itself. The free wheeling could last for 4 or 5 seconds which could then be followed by the regenerative braking slowly gaining strength. This would prevent the abrupt deceleration that currently occurs when this happens and give the driver a few seconds to realize what just happened and act accordingly. Of course the ultimate goal would be to eliminate the self-disengaging of the system, but that will never be 100%. There will always be circumstances where the system gets "confused" and need to turn control back over to the driver.

I'll continue to use the ACC because it's really a great feature, but I'm always "at the ready" while using it. I wanted to write this post for the new i3 owners out there that follow here just in case you weren't aware of this issue. I was actually inspired by a follower of this blog who recently got an i3 and sent me an email asking about this. He was concerned that it was a problem with his particular car. So if you are new to the i3 and the ACC feature, just be ready at all times to respond with some throttle and you'll have nothing to worry about. I'm sure BMW is aware of this and already working on a solution. I don't believe it can stay like this without some kind of update to eliminate or minimize the abrupt deceleration following deactivation. At some point, it will cause an accident if not addressed.

10 comments:

  1. I think free wheeling when ACC it is disengange is not gut because people trust in system I think all go good and don't breakst in this case. Maybe one or two secons free wheeling.

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  2. Instead of being ready to hit the accelerator, can't you just have your thumb hovered over the resume (RES) button? It hasn't shut down on me in a while but I believe that the RES button does the trick.

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    1. Hi Drew,

      Yes I suppose that would work also, I'll have to try it out. The only question I have it whether the ACC will allow you to instantly reactivate it once it disengages, or if there in some kind of "time out" for 5 or 10 seconds when it manually disengages. I'll definitely try it. Ultimately, BMW needs to fix it so it happens much less frequently. I can understand every once in a while, but I believe this happens too frequently to be considered "normal" operating parameters.

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  3. This is indeed an important issue, important enough that I put it on my EV checklist (on my website, click on my name). But for me, it was on the list on the basis of having experience the lurch that the Volt gives you when manually cancelled out of cruise control.

    It was more of an aesthetic complaint, and I learned to depress the accelerator slightly before canceling the cruise. The BMW i3 ACC problem is more serious. Hopefully you writing about it here will draw BMW out and get them to a real fix, to be retroactively applied to 2014 i3 units.

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  4. In addition to the ACC disconnects described well in this blog, my i3 seems blind to certain vehicles and would gladly drive into them without my intervention. Examples are a Gasoline Truck (shiny convex tank), Flat Bed Truck, Steel Mesh Trailer pulled by a car, and a large truck at night with no working taillights!

    Has anyone else had this experience? I've also had the system stop working a couple of times with an "internal error" message. I'll ask the dealer about all of these phenomena when I take it in for an onboard charger upgrade (service action B61 31 14) in a couple of weeks. Thanks.

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    1. No Bob I haven't experienced a situation where the car didn't recognize another vehicle or obstacle in its path. My experience seems to be the other way, and it can recognize something like an overpass and confuse it with a vehicle and disengage. The disconnecting seems to happen less than it did when the car was new, but it does still happen.

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    2. Thanks for the info. I'll be sure and report this as a problem to the dealer.

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    3. Hi Tom and Bob,

      I have still these problems. The car was in for software update in August. Second time in November, they ordered a new camera and steering column. Changed them last week with an 6h software update as well. Steering is great, until now the steering wheel has been loose?! Regarding the ACC I noticed like before the constant disengage. Worst is also that the system missed a big cement truck in front of me like Bob also described.

      ACC feature cost me $ 4000 because ACC is not an option in standard interior?! I don't know how to proceed, I don't want to turn back the car.

      /Johan, Sweden

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  5. I have the i3 for 3 weeks and use it daily - great eDrive, like the interior but can't use the cruise control so big disappointment. Reason: in the morning I drive the i3 to work eastbound on the LIE and the cruise disconnects when the sunlight hits its sensors. Then, in late afternoon I drive it westbound (my daily commute is 26 miles each way) and the same thing happens. I called BMW NA and they said that I can't disconnect the sensors (I requested them to disable the Stop and Go functions and make the cruise control a traditional one) so now I plan on fighting BMW on lemon law basis and take the car back. I wouldn't have leased the i3 had I known I can't use cruise control to and from work. Anyone else experiencing the same issues on a daily basis? Thank for reading. Ron

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  6. Interestingly, when I try to engage the system when driving into direct sunlight, it mistakenly claims that the sensor is dirty and needs to be cleaned.

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