Cruise Control issue? Looking for a little feedback

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My 2013 and Radar CC is not jerky in the slightest. The issue being discussed is when the vehicle is out of the specific cruise control speed window or so I'm believing *correct me if I'm misspeaking*

Example:
If the cruise is set to 55 and during a hill descent the speed exceeds this by ~10 MPH, then the vehicle will downshift to engine brake. Hence the increased RPMs.

The inverse happens if the vehicle is ascending a hill and the speed drops, the tolerance is closure to 1-2MPH though, the transmission will downshift and throttle up.
 
CLHickman said:
My 2013 and Radar CC is not jerky in the slightest. The issue being discussed is when the vehicle is out of the specific cruise control speed window or so I'm believing *correct me if I'm misspeaking*

Example:
If the cruise is set to 55 and during a hill descent the speed exceeds this by ~10 MPH, then the vehicle will downshift to engine brake. Hence the increased RPMs.

The inverse happens if the vehicle is ascending a hill and the speed drops, the tolerance is closure to 1-2MPH though, the transmission will downshift and throttle up.
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In my case the Radar CC will sometimes downshift twice to achieve the desired speed. These downshifts can be abrupt and noticeably jarring. Revs can increase by as much as 2,000 RPM's. First time it happened my wife asked what was wrong with the car. My reaction was the same....yeah, what IS wrong with this thing?
 
I believe a lot of the "jerkiness" (is that a word?) has to do with the 8-speed transmission. They likely have the ECU tuned to keep the engine in a narrow RPM range to get maximum fuel economy, and the Radar CC is also overly sensitive due the liability.

I found my CC is MUCH smoother if I turn off (disable) the ECT setting. It is less likely to downshift on slight upgrades.
 
Bob Frame said:
In my case the Radar CC will sometimes downshift twice to achieve the desired speed. These downshifts can be abrupt and noticeably jarring. First time it happened my wife asked what was wrong with the car. My reaction was the same....yeah, what IS wrong with this thing?
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I see what you're saying. I do have the same thing that happens if I'm trailing a slower driver for a minute and move out to pass. The transmission will shift to 5th, then quickly shift to 4th or even 3rd. The car makes some super speedy calculations based on the difficulty it is having to get up to the required speed, so sometimes it makes drastic choices. I've experienced all of those combinations at some point.

Another area where this happens often is when I'm coming off an onramp entering the freeway. I'll be going roughly 35 MPH and I'll set the cruise to 70 or 75 MPH. It will hammer down to get me there. I guess I could incrementally increase the CC setting from the stalk, mine goes by 5 MPH, until I get to 70 at a more leisurely pace.

My point is, I know when these shifts are going to happen. I know if I'm starting to increase speed going down a hill that a downshift is coming or braking is applied automatically. Also, If I'm behind someone and change lanes because they're going quite a bit slower, the system is going to want to get me up to speed fast.

I'd hate to see you ditch the truck because of the cruise feature. It may just take a little more engagement or getting used to. There are different vehicles with better systems, which I totally agree on, but they don't really hold a candle to the other capabilities this thing offers.
 
What you describe seems to be normal behavior for any automatic transmission in response to more throttle...a downshift in response to a depressed gas pedal. I completely accept this. What's new for me is the aggressive downshifting, sometimes two downshifts in response to, IMHO, very moderate hills while the CC is running the show. Not my first CC, not my first Lexus LX...but this transmission operation is new territory for me. And quite frankly I don't like the way this unexpected shifting feels. Its not making me feel great about my buying decision and for this kind of money I should be on Cloud Nine.
 
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Noah Miller said:
Used it this morning on hilly commute. Normal CC=Normal Driving as if you have the throttle in 1 position, no other inputs used.
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I've tried a similar test and I "think" I agree with you though I want more inputs...different roads.

So here's my question, does it make any sense that the Toyota engineers designed one set of transmission "protocols/behaviors" for the Radar CC, but a different set for the "Normal CC"?

I understand that in the Radar mode they build in the "anti-tailgating" models, but with zero cars out front why would they envision one set of behaviors in Radar CC, but a different set of behaviors in "Normal"CC? This doesn't make any sense to me, but then there's a lot about this LX that doesn't make sense to me.
 
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as mentioned, took it out the other day to an expressway that goes for a number of miles and has multiple overpasses. First I put on ECT and the CC with radar on - there weren't many cars around so the radar did not actually have to slow the car. The jerking going down the overpasses did not seem to be quite as bad as with the ECT off. But, the jerking was still there and noticeable to me and another in the car. I have even been asked in the past, when I tried this, if there is something wrong with the car while driving....

Next I reversed the route with both ECT and S mode enabled - gear 5. Acted the same as with only ECT on.

The speed was 54mph.

Experiencing this on the highway at 77mph is still noticeable and unusual to me, but once again maybe not as as much. Maybe due to the speed difference 54 vs 77? Who knows.

just seems like a not so good of a design.
 
I have been experimenting as well...using the "Normal CC". This is engaged by holding in the cruise control "on/off" button at the end of the stalk for 1.5sec. You know its engaged when the CC symbol on the dash changes. I've driven in rolling hills with CC set at 55-60 and on a rolling highway section with CC set at 65-70. In both cases I find that the CC gently downshifts once to go up a grade, but only one gear. It has not downshifted to slow the vehicle on the downhill sections. I watch the rpm's carefully and find that the engine runs at 1600 rpm's on a flat stretch and usually reaches 1800-2000 on a climb. I need to test these same stretchs with the radar CC on to see if I can get it to do the "herky/jerky" shifting.

But as of right now I am pleased with how the CC is running...its very reminiscent of my '06 LX470 (the finest automobile EVER made on this planet-IMHO). For now I see no reason to ever run the Radar CC again.
 
ToyotaTrk said:
....I also am looking for a little feedback on the cruise control - I explained that when using the cruise control and going highway speed, 55-65, and going up overpasses the car downshifts to speed up and keep speed. From about 1500rpm to about 2300 I think. So far normal I think.... But on the downside on the overpass, the truck downshifts to slow down and keep speed and the rpm's jump to 3400-3500 - heres the issue - its pretty jerky. It bucks a bit - a little too much I think. Then when it slows back to speed it bucks agin. Just seems rough to me....
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Sorry for reviving an old thread, but I'm have the same cruise control "bucking" issue as the OP. Any hint of a TSB for this?

Thanks, Mark
 
Car still jerky. People ask from time to time, what was that.?.

When it starts to acting that jerky way, I just disengage the cruise until I get to some flat road......
 
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