Cruise out of Control?
02-27-13, 05:38 PM
#1
Lexus Test Driver
Thread Starter
Cruise out of Control?
The cruise on my 2013 LS460 SWB RWD sucks big time! Both Dynamic and Normal cruise modes are WAY too sloppy in speed regulation. I was out today on a 55mph PSL two-lane with set speed of 59mph. On a long SLIGHT downhill, the indicated speed topped out at 70MPH!!! BTW, tranny shifting was weird during this episode with a prolonged run at over 3k RPM. At any rate, that's 11mph over the set speed for the arithmetically challenged. So instead of tooling along at a maximum of 5 over the PSL as my 2007 LS would have done (set speed 59 + overspeed 2 = 61 indicated = 60 actual, so 5mph over PSL), I'm flying at 10mph over the PSL ripe for the picking by any county sheriff (and I saw THREE of them on that road, all with their radar on). WTF??
I figure my car's speed regulation (in both Dynamic and Normal cruise) is +11mph/-2mph for set speed of 59mph. That is crazy!
What kind of speed regulation are you guys experiencing?
I figure my car's speed regulation (in both Dynamic and Normal cruise) is +11mph/-2mph for set speed of 59mph. That is crazy!
What kind of speed regulation are you guys experiencing?
Last edited by williakz; 02-27-13 at 05:44 PM.
02-27-13, 05:41 PM
#2
Lexus Test Driver
Thread Starter
NOTE: Following was originally posted under my Florida Trip post, but I thought I'd put this in a cruise control post.
Dynamic Radar Cruise Control definitely has a learning curve associated with it. It works best in the simplest situations and becomes progressively less useful as traffic density - and complexity - increases.
First, the system is quite a bit sloppier in speed regulation mode than I'm used to. My previous LS with "standard" cruise regulated speed to +/- just a few mph. DRCC is happy to let me go 5 to 7 mph over the set speed. That's a bit much if your set speed is already over the posted speed limit (PSL). That said, the system is quite responsive in distance regulation mode, braking almost exactly at the same time I would (so you don't feel panic that the system is sleeping) and applying the brakes firmly but not abruptly. Note that this version of DRCC will brake the car from whatever the set speed is all the way down to a full stop (say for the one red light in a small town along a two-lane highway). When this occurs, you must goose the accelerator just a tad to get DRCC back in action once the light turns green.
The system really fails in moderate to heavy freeway traffic because the separation distance between me and the car ahead is just too large. It encourages cars behind me to pass me on the right and jump into the two-to-three car length space in front of me. When they do, DRCC slows down to maintain its minimum separation and the next guy pulls the same routine and so on and so on. The way to get around this is to override DRCC's gap by closing it manually until conditions become slightly less congested. I should note that if Lexus shortened DRCC's "gap," the system would have to operate much quicker and braking and acceleration would necessarily become somewhat more noticeable, possibly to the point of annoyance.
You must always "tend" the system. If not, you can find yourself in some dicey situations. For example, you're on a 65mph PSL four-lane highway that slows to 55mph then 45mph then 40mph as it passes through a small town with several traffic lights (all green). Your set speed is 73mph and you're in distance regulation mode with the guy in front of you going at exactly the PSL at all times. Eventually you find yourself going 40mph behind him when he decides to move out of your lane so he can pull into the Burger Doodle. If you haven't been paying attention, you'll find yourself doing the PSL (40mph) with a 73mph set speed and an open road ahead. The car will take off like a banshee and you'll be the one screaming! Therefore, I always make sure I'm lowering (and raising) my set speeds as the PSLs go down (and up) even when I'm in distance regulation mode. So, no surprises. Note that this same effect can occur when you change lanes causing the mode to go from distance to speed regulation. You think you're just making an easy lane change out from behind a slowpoke, but the car sees open road and rapidly accelerates to reach its set speed. It is disconcerting to say the least. DRCC demands your attention! Probably it becomes second nature after a while, but I don't have the knack quite yet.
One great feature of Lexus's DRCC implementation is that immediately after actuating it, you can push the wand forward and it will switch into "normal" cruise mode (speed regulation only) so you (or someone leery of DRCC) can still function with a familiar cruise control system.
Addendum: Had several days of rain during my recent Florida trip. DRCC is very iffy during even moderate rain. It tends to cut out (auto-disengages) when visibility deteriorates. I'm not sure exactly what it "sees" using the camera under the rear-view mirror, but mist thrown up by car tires seems to kill it every time. Don't know about fog. [I'm informed this camera is not for DRCC]
Dynamic Radar Cruise Control definitely has a learning curve associated with it. It works best in the simplest situations and becomes progressively less useful as traffic density - and complexity - increases.
First, the system is quite a bit sloppier in speed regulation mode than I'm used to. My previous LS with "standard" cruise regulated speed to +/- just a few mph. DRCC is happy to let me go 5 to 7 mph over the set speed. That's a bit much if your set speed is already over the posted speed limit (PSL). That said, the system is quite responsive in distance regulation mode, braking almost exactly at the same time I would (so you don't feel panic that the system is sleeping) and applying the brakes firmly but not abruptly. Note that this version of DRCC will brake the car from whatever the set speed is all the way down to a full stop (say for the one red light in a small town along a two-lane highway). When this occurs, you must goose the accelerator just a tad to get DRCC back in action once the light turns green.
The system really fails in moderate to heavy freeway traffic because the separation distance between me and the car ahead is just too large. It encourages cars behind me to pass me on the right and jump into the two-to-three car length space in front of me. When they do, DRCC slows down to maintain its minimum separation and the next guy pulls the same routine and so on and so on. The way to get around this is to override DRCC's gap by closing it manually until conditions become slightly less congested. I should note that if Lexus shortened DRCC's "gap," the system would have to operate much quicker and braking and acceleration would necessarily become somewhat more noticeable, possibly to the point of annoyance.
You must always "tend" the system. If not, you can find yourself in some dicey situations. For example, you're on a 65mph PSL four-lane highway that slows to 55mph then 45mph then 40mph as it passes through a small town with several traffic lights (all green). Your set speed is 73mph and you're in distance regulation mode with the guy in front of you going at exactly the PSL at all times. Eventually you find yourself going 40mph behind him when he decides to move out of your lane so he can pull into the Burger Doodle. If you haven't been paying attention, you'll find yourself doing the PSL (40mph) with a 73mph set speed and an open road ahead. The car will take off like a banshee and you'll be the one screaming! Therefore, I always make sure I'm lowering (and raising) my set speeds as the PSLs go down (and up) even when I'm in distance regulation mode. So, no surprises. Note that this same effect can occur when you change lanes causing the mode to go from distance to speed regulation. You think you're just making an easy lane change out from behind a slowpoke, but the car sees open road and rapidly accelerates to reach its set speed. It is disconcerting to say the least. DRCC demands your attention! Probably it becomes second nature after a while, but I don't have the knack quite yet.
One great feature of Lexus's DRCC implementation is that immediately after actuating it, you can push the wand forward and it will switch into "normal" cruise mode (speed regulation only) so you (or someone leery of DRCC) can still function with a familiar cruise control system.
Addendum: Had several days of rain during my recent Florida trip. DRCC is very iffy during even moderate rain. It tends to cut out (auto-disengages) when visibility deteriorates. I'm not sure exactly what it "sees" using the camera under the rear-view mirror, but mist thrown up by car tires seems to kill it every time. Don't know about fog. [I'm informed this camera is not for DRCC]
Last edited by williakz; 02-27-13 at 05:51 PM.
02-28-13, 08:53 PM
#4
03-01-13, 12:30 AM
#5
Right. Manual also explains separation distance is adjustable to 3 different distances. I not sure thae way the 2013 works but i believe the default following distance is long mode. Setting it to "short" puts you pretty close to traffic you're following and rarely will someone cut in front of you.
In distance following mode,
Cruise will disconnect any time wipers go to fast mode
will not work in snow mode.
Will deactivate when VSC is activated
I had dynamic cruise on my Avalon and it worked very well once you knew how to maximize the features.
JR
.
In distance following mode,
Cruise will disconnect any time wipers go to fast mode
will not work in snow mode.
Will deactivate when VSC is activated
I had dynamic cruise on my Avalon and it worked very well once you knew how to maximize the features.
JR
.
Last edited by FLYCT; 03-01-13 at 12:46 AM.
03-01-13, 09:46 AM
#6
Lexus Test Driver
Thread Starter
On the problem I mentioned with people passing me on the right and cutting into the large space in front of me, this occurred at the "short" distance setting. I typically use short in moderate to heavy freeway traffic, medium on secondary roads around town, and long only after my car goes into the clear in light or no traffic (to give me most warning on next "encounter"). The MANUAL (p.251) states that at 50mph set speed, the "short" distance setting is approx. 100ft. and since the vehicle is 16.7ft long, the " minimum gap" I said was too large works out to be almost SIX CAR LENGTHS at 50mph and even larger at higher speeds. Do you really consider a 100ft buffer "close to traffic" and sufficiently small to discourage others from cutting into it? I don't and the many other drivers on the road passing me on the right apparently don't either.
I am interested in your input on the poor speed regulation of 2013 Lexus cruise. What do you think of +11/-2 mph on a set speed of 59mph? Thanks in advance for your opinion.
03-01-13, 10:14 AM
#7
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03-01-13, 04:56 PM
#8
either you're not doing something right to the car or the car is malfunctioning. In either case you need to call your service person.
03-01-13, 05:04 PM
#9
Lexus Test Driver
Thread Starter
What problem are you referring to? The poor speed regulation of the cruise control system or its oversized "gap" (documented in the manual) that makes distance regulation in dynamic cruise effectively useless in other than the lightest freeway traffic?
03-01-13, 05:58 PM
#10
what you're complaining about is normal system operation, You should've tried it out on your test drive since you're so paranoid about its operation. When you call service they will tell you the same. Like I said in my last post, you need professional help. Peace out!
03-01-13, 09:03 PM
#11
Lexus Test Driver
Thread Starter
Surely you cannot defend the sloppy speed regulation I reported (11mph overspeed?) Yet you castigate me for objecting to Lexus changing the operation of this function. As I also reported, my 2007 LS was +/- 2-3mph max under exactly the SAME driving conditions.
As far as Dynamic Cruise, I admit I am learning the function and have truthfully reported my experiences with it. The function CANNOT be used in moderate freeway traffic because the shortest gap is so large other drivers pass on the right, fill the gap, and force the vehicle to slow even more to recreate the gap which sends more cars around the right and into the gap. It never ends.
Either address my concerns with data, properly sourced information, or informed opinion. As far as casting aspersions regarding my sanity or intelligence, please keep them to yourself. Oh, and FOAD.
03-02-13, 08:22 AM
#12
Lexus Test Driver
Thread Starter
Cruise controls are not designed for slope, uphill or downhill, or freeway driving or on poor-traction surfaces such as snow, ice, gravel or wet roads.
I don't think the cruise control has to be enable for those nice features to work. If you are uncomfortable with the PCS braking then that can be disabled by the press of a switch under the dash.
03-02-13, 08:28 AM
#13
This is just wrong. Of course CC "controls" max speed in downhill situations. While I agree it does not (and probably should not) apply braking, It does controls both throttle AND drive gear to maintain set speed. Think how CC downshifts and applies more throttle when vehicle speed drops in an uphill situation. It reduces throttle and uses engine braking (lower gear) in downhill situations. Furthermore, my situation was NOT a steep decline but rather a long gradual downslope easily controllable by moderate throttle/gear selection well within the capability of every CC system I have driven to date. The difference between CC function in my 2007 LS and my new one is the specific concern I voice here.
This is just silly. Of course CC is designed to address real-world driving conditions which include all of the above. Common sense rules and using CC on a wet, snowy, muddy, one-lane dirt road in the West Virginia mountains is not going to work. But encountering hills while cruising the interstate is de rigeur and represents no problem for any CC system. Again, how did the CC on my 2007 LS function so well at speed regulation while the 2013 system does so poorly?
This is just off the wall. I made no comment about being "uncomfortable" with "PCS braking" whatever you conceive that to be. If you mean the active collision avoidance system as implemented in Lexus's Advanced Pre-Collision System (APCS), well I don't have that on my vehicle. If you think automatic braking operates on Lexus's basic Pre-Collision System (PCS), then you're just wrong. In either event, you are addressing a point I never raised.
This is just silly. Of course CC is designed to address real-world driving conditions which include all of the above. Common sense rules and using CC on a wet, snowy, muddy, one-lane dirt road in the West Virginia mountains is not going to work. But encountering hills while cruising the interstate is de rigeur and represents no problem for any CC system. Again, how did the CC on my 2007 LS function so well at speed regulation while the 2013 system does so poorly?
This is just off the wall. I made no comment about being "uncomfortable" with "PCS braking" whatever you conceive that to be. If you mean the active collision avoidance system as implemented in Lexus's Advanced Pre-Collision System (APCS), well I don't have that on my vehicle. If you think automatic braking operates on Lexus's basic Pre-Collision System (PCS), then you're just wrong. In either event, you are addressing a point I never raised.
