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ACC woes, differences and questions

11K views 73 replies 11 participants last post by  M8TJT 
#1 ·
So over in the traffic sign recognition thread M8TJT and I went a bit astray talking about the cruise control.

He doesn't like the braking of the ACC going downhill (without following someone). Instead he would like it to coast like it did in the previous generations.

I, on the other hand, would have said, that my car is not braking while going downhill. I am annoyed however by the following behavior as it is way to precisely keeping the distance on the two bar setting I normally use, which gets horrible when someone in front of you is goin 70 75 70 75 in 5 second intervals.


To pick up on that, I've tested today and can definitely say: My car is coasting downhill, no braking whatsoever. So it seems like the Type R has a different implementation of the ACC than the normal 10G - which I find rather curios. OR I have accidentally fiddled with some setting affecting it without me realizing :surprise:

I still don't know if and when the brake lights turn on - if someone is doing the 70 75 70 thing in front of me and my brake lights turn on every time I probably look like a total idiot. Do I have to mount a camera to find out?
 
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#2 ·
Easy way to see is if the area around the center break light is a little fogged up in the sedan/limousine. I can confirm that the ACC in the non type R 1.5's also breaks a lot more than I normally would.

Turning off the cut in prediction control helps especially with it slowing down for cars leaving the motorway.

Reducing your speed using the set - button will cause the system to break for you if you drop the set speed by more than 10kph. Although it will break for a 10 reduction if you're going downhill. Generally though I've seen that a 10kph variation by you or the car in front of you it doesn't break.

I was hoping by turning on the ECON button that it would coast more. Nope. According to the US manual you can switch from ACC to normal cruise control so it won't break for you anymore, not mentioned so far in the European manual. I'm at page 4 hundred something still though.

I'm assuming like the 9G hatch it's difficult to see the center break light in the 10G hatch in the rear view mirror during the day?
 
#3 ·
I had a UK 9G hatch on loan a couple of days ago and it did not brake on downhill, and oversped my set speed by about 10MPH.
My 10G however applies the brakes, and I find that it seems to be controlling the speed to tightly and tends to 'hunt' a bit normally, accelerate, brake, accelerate, brake etc. It's the braking that annoys me, just let it roll. I can understand the need for braking in the follow mode and I usually follow at 4 bars because I find 2 a bit close for open road follow.
Must see if I can see the centre brake light to see what's going on. Must see if the 'cut in' prediction changes anything, but I doubt it as no other car is involved anyway.
 
#12 ·
Yes, that's exactly what I found. But as I said before.
My 10G however applies the brakes, and I find that it seems to be controlling the speed too tightly and tends to 'hunt' a bit normally, accelerate, brake, accelerate, brake etc. It's the braking that annoys me, just let it roll.
That's even if the 'accelerate' part is a downhill coast. It needs a bit less tight control of the overspeed breaking.
Mine even displays the same on the flat, with the accelerate phase engine rather than gravity generated.
 
#4 ·
I've noticed the hunting you mention. It's particularly bad in 6th at around 80kph 50mph. Couldn't see the break light at the time to see if it was just on and off the gas or if breaking was involved.

Yup wife's 9G cruises too, they didn't get ACC.
 
#6 · (Edited)
It seems that reducing the speed by 10mph or more (e.g. by holding the - button) will trigger braking, however reducing by smaller amounts results in just reducing the throttle.

I find the 3 bar distance setting to be a good distance for motorway driving in normal/dry conditions. Also, I like the fact that when a vehicle cuts in front of you - breaking is only triggered if they are going slower or at the same speed that you are - most of the time people who cut in will be going faster.

I felt the ACC made my long motorway journey to Dorset last week much less tiresome, especially on the busy M25 which would usually make the use of basic cruise control impractical due to the almost constant changing of speeds. Having the car automatically keep pace with changing traffic speeds while maintaining a safe distance is wonderful and the ACC is probably my favourite feature.

I've not had any issues with the cut in protection and I find that it works exactly as it should, there are so many bad drivers who will look for any opportunity to undertake and it's clever that the car can detect that. I've not noticed the hunting behaviour mentioned above, my 10G is the 1.0, could that have anything to do with it?

As for the other safety features. I find the lane keep assist to be excellent when cruising, applying gentle torque on the steering wheel to guide you, and of course the lane departure warning that vibrates and applies opposite torque on the steering wheel if you cross a line without signalling or indeed vibrates if it feels you are not positively controlling the car. The blind spot protection is excellent and very useful and the cross traffic monitor combined with the wide angle camera view is fantastic when reversing out of the driveway or a parking bay. Granted, the traffic sign recognition is not really up to scratch - it reads the variable speed limit 60 signs as 80 on the M25 and also sometimes misses signs that I've seen! Overall though, I think the technology on board is very well implemented and very easy to use and makes the car much safer. It feels a world apart from my previous 9G EX.
 
#7 ·
So my 10 pennies to the conversation.
With the Prestige and CVT the ACC coast downhill and will not brake until I manually brake or a car / obstacle gets in front.
Long hold on the - button so it changes 10 kmh or more it will brake to set speed but then start coasting again in a downhill scenario.
I drive through Stockholm daily to and from work and there are a lot of traffic so I tend to use 1 or 2 bar length to the car in front. Mostly 2 bars and then the cut in protection can be a bit to protective, making the car behind, that is often to near my back end, almost hit me. I've learned to put my foot gently on the accelerator to negate the effect when I notice it starting to happen and there are no danger to do it.
Also with the 4 or more lane roads that have fairly narrow lanes, I feel that ACC has trouble knowing which lane I am in and which the cars next to me are in so it brakes for "no reason" from time to time.
I will try and disable the the cut in protection to see how it differs in that regard.

Several times I have gotten warnings for either to much rain or no radar due to snow or dirt on the panel in front of the radar and the ACC stopped working. Even after I have wiped off snow or dirt from the radar panel it still would not work until it had dried a bit in my garage. That is kind of annoying and a poor implementation for the conditions we have in colder or dirtier parts of the world.
 
#8 ·
With the Prestige and CVT the ACC coast downhill and will not brake until I manually brake or a car / obstacle gets in front..
But if the hill is steep enough, does the car then coast to a speed higher than what you have set as the CC speed? Mine will brake to keep the speed down, but the 9G that I had on loan just exceeded my set speed when coasting by 15MPH until I ran out of hill.
 
#14 ·
I would have expected it not to apply brakes on a downhill slope, too much chance of overcooking the brakes.

My only other car with an automatic, does slow down downhill, but by downshifting never by applying the break (different manufacturer). If the hill is steep enough it will exceed the set speed by more than 10kph. Given that the CVT in the Honda has next to no engine breaking, I would expect it to speed up quite a bit downhill.

My 10G is a 6MT, also no hills nearby to test it out.
 
#17 ·
I wonder if the Type R inherited the ACC from the 9G Type R and is coasting because of that - it only brakes when I set the speed lower with 10 km/h steps.
 
#18 ·
One of the first things my ADI said, many years ago, is that you use the brakes to slow the car, not the gearbox, because brakes are cheaper to replace.

If you dropped a cog to slow the car on the AD test - fail
 
#19 · (Edited)
I'm going to have to disagree with your ADI there. If you know your route, there is no need for braking, and Rev matched downshifts while coasting to a slower speed should not add wear and tear to the engine or gearbox. I have yet to wear out a synchro or replace a clutch plate for that matter.

Had to sell my civic in the UK, we moved out of the country, but after 3 years and 36k miles on it. On inspection 90% brake pad life left, they thought I'd changed them at some point. There's even a post on here where I caught the infamous rear caliper sticking early. Doesn't get much worse than mostly in town driving for 3 years and that many miles.
 
#20 ·
Engine braking doesn't work very well with modern engines anyway, unless you have dump valves to dump the compressed air generated by the compression stroke. >:)
Opinion differs on cog swapping, but my take is that you should always be in the 'right' gear for your road speed which obviously involves changing down as you slow regardless whether or not you are using the engine braking effect.
 
#23 ·
Yup, agreed. The 10G ACC system is too brake happy.
That's a really good way of putting it. The other problemette is that any following drive will think "What's that plonker doing keeping on braking" when he sees your brake lights going on and off.

Along the same lines, when brake hold is on, the brake lights are on when you are stationary, with the possible affect of dazzling the driver behind at night. You can use the handbrake under these circumstances as, when on, there are no brake lights and it releases automatically when you drive off. I haven't tested it under auto-stop conditions but suspect it will be the same.

I cannot understand why they put the brake lights on when stationary with brake hold. Stupid.
 
#24 ·
That bugged me too. I liked the idea of brake hold, till I noticed the lights. I thought it was applying the EPB, turns out it maintains hydraulic pressure on the brake lines as if you've got your foot on the brake. Neither continued hydraulic pressure nor blinding the driver behind appealed. So I switched to applying the EPB and allowing to auto release when driving off.

Don't like auto stop, so always turn it off when I get in the car. I can't comment on that area of functionality. There aren't enough stop and goes or traffic lights on my usual commute to warrant it anyway.
 
#25 ·
Don't like auto stop, so always turn it off when I get in the car. I can't comment on that area of functionality. There aren't enough stop and goes or traffic lights on my usual commute to warrant it anyway.
Then you might as well leave it on then.:grin2:
My auto stop seems mostly to come up with an A with a line through it and battery low or Temp low or just the A with a line through it. I have had it actually work on some rare occasions though.
 
#29 ·
I seldom use brake hold (mainly because I have to press the button every time I get in) that's why I have full control over my brake lights.

As I wrote I only turn them off when somebody is behind me as otherwise some fast approaching idiot will crash into me. So in order to make brake hold do the same thing it would have to sense a car behind me and then switch the lights off.

Desperately trying to get this post back on topic, but nothing more I can say about ACC right now :serious:
 
#30 · (Edited)
I think it's all been said. Could do better.
As I wrote I only turn them off when somebody is behind me as otherwise some fast approaching idiot will crash into me.
I just realised that this is a silly non-valid argument against brake lights going out when stationary on brake hold, as you always have the option of keeping your foot on the brake pedal.:grin2:
 
#31 ·
Been cruising along with 3 bar setting the last couple kilometers and I noticed something new (for me). First of it seems to be a bit smoother in the 3 bar setting.

The distance between my car and the next car is so high, that it actually looses the vehicle in front. So the car indicator gets dotted. I expected it to speed up, but the ACC will not accelerate if you have a certain degree of steering going on. It will hold the current speed until you drive more straight again. Interesting, I guess this solves two problems. First is the obvious loosing the car in front and second is the dangerous part of accelerating while in a curve.
 
#33 ·
2 bars before, almost all the time. I don't like the 3 or 4 setting on Autobahn - it detects vehicles too late and starts breaking really hard. But probably my Autobahn driving style is not considered safe driving - still most people fall asleep while driving with me, so it can't be that bad...

But I don't know why there is a 1 bar setting, that's definitely way too close for my liking. Well actually the 2 bar setting is too close as well.

1 bar: 1.1 seconds
2 bars: 1.5 seconds
3 bars: 2.1 seconds
4 bars: 2.8 seconds

Required by German authorities: at least 1.8 seconds. But yeah the manual says that it is the drivers liability to select the right distance setting - back on the Autobahn I'll probably go down to 2 bars again.
 
#35 ·
How does that old adage go "Only a fool breaks the two second rule."?>
Oh plenty of those on the autobahn. Tailgating, as the Americans call it, is a way of life here. God forbid you should overtake somebody while doing the speed limit (yes some sections of the autobahn have speed limits). It's like you've committed a crime, they get up right into your tailpipe. Even at 130kph!

I like vmaxing a car as much as the next guy (attached, no I didn't take them while driving). I've been up to 250ish kph when safe and legal. But when there's a limit set, I stick to it. Besides hgvs, I'd typically be the slowest vehicle on the road. There's no 10 plus 1 rule here, according to German laws they can fine you for being over by 1kph. I doubt that they do, and the fines are a joke compared to the UK, but why bother for a few seconds off a trip.

To bring it back to the ACC, and why I turned off the cut in prediction, it makes it almost impossible to overtake. Imagine it braking in the overtaking lane with someone trying to crawl into your tailpipe!
 

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#36 ·
I must say that disabling the Cut in protection was so far a good thing.
The ACC is now much smother in traffic. It still brakes when a car switch to my lane in the space between me and the car in front, but it is more subtle and smooth instead of slam the brakes as with Cut in enabled.
Also much smoother on roads with narrow lanes as it doesn't detect lorries and big cars in the lanes beside as a potential cut in and brakes for no reason.
 
#37 ·
Thanks for the 'heads up' on the 'cut in' chaps. I now intend not to experience it myself by nipping out to the car and switching it off in a bit. I don't want the car to brake hard just because it thinks it should when I am happy(ish) about the situation.
 
#38 ·
ACC - I have not nor plan on using this feature, unless I am on my way to France and it is very late at night...

Cars are for driving and I like to be the one driving it - not the car... Take the fun and experience out of it..
 
#42 ·
Switched off mine yesterday. I can usually tell if someone has 'cut in on me'. Only if the cut in car does so really super aggressively does it need serious input from you. Usually the only driver input needed is either a 'lift' or light brake to slow down a bit.

Can it tell the difference between someone just slotting into the gap and a super aggressive carve up where possibly hard self preservation braking is required? From the handbook, it's quite difficult to get your head around as to exactly what it is 'testing' for before it takes action.
 
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