Unsettled Cruise Control

[rossmon1]

I have noticed recently that the CC will behave in a disconcerting manner with downshifting and then accelerating hard to get to the set speed. Usually this was goinon uphill. The grade could be minor. The t4r would be gradually accelerating lets say to 50mph to reach a set peed of 55 and then wham it downshifts and pulls past 55 b4 settling back at 55. This could be very disconcerting on twisty roads.

 

[sharp4runr]

Yeah I've seen that behavior as well. Sometimes you are just cruising say at 50MPH and then you come up on a hill. Because of the weight of the truck it has to increase the throttle to maintain the set speed. It does it with A LOT and could be a lot more gradual...

 

[Koz]

If the speed set (with CC) is somewhat more (more then 3 or 4 mph) then your current speed, most CCs will downshift to reach the set speed ASAP. Any load or upgrade will trigger the downshift quicker. This is normal for most CC. Every vehicle I've owned has done this.

Koz

 

[Iowa4Runner]

I have noticed recently that the CC will behave in a disconcerting manner with downshifting and then accelerating hard to get to the set speed. Usually this was goinon uphill. The grade could be minor. The t4r would be gradually accelerating lets say to 50mph to reach a set peed of 55 and then wham it downshifts and pulls past 55 b4 settling back at 55. This could be very disconcerting on twisty roads.

At 50 mph in top gear the RPM is so low that even at nearly open throttle, the engine won't do much. However that same throttle setting in 4th gear (at 50 MPH) the engine is much more lively. Toyota probably didn't put too much effort into the cruise control algorithm, and didn't take this into consideration. For cruising at 55 on hilly roads, your best bet is to keep the shifter in 4th gear

 

[Koz]

Toyota and most all manufactures have put much effort into the design of CCs. If your traveling on a hilly road you simply put the selector into a lower gear and it will not downshift when the CC is engaged. This is why Toyota recommends you use 4th to tow (to have less downshifting). If you're traveling at 30mph, with the CC on, and want to set the CC at 40mph, you can hit the speed increase button (on CC) 2 or 3 times repeatedly. (Each time you hit the button you will increase the speed by 1mph) When the speed starts to increase you can hit it a couple more times to get up to the speed you want. As long as you don't request too much (MPH) at one time it will not downshift. If you hold the increase button the system will request a downshift to reach the higher speeds.

Koz

 

[Iowa4Runner]

Toyota and most all manufactures have put much effort into the design of CCs. If your traveling on a hilly road you simply put the selector into a lower gear and it will not downshift when the CC is engaged. This is why Toyota recommends you use 4th to tow (to have less downshifting). If you're traveling at 30mph, with the CC on, and want to set the CC at 40mph, you can hit the speed increase button (on CC) 2 or 3 times repeatedly. (Each time you hit the button you will increase the speed by 1mph) When the speed starts to increase you can hit it a couple more times to get up to the speed you want. As long as you don't request too much (MPH) at one time it will not downshift. If you hold the increase button the system will request a downshift to reach the higher speeds.

Koz

This is the same canned CC routine that many cars have had for many years. If Toyota had really put in the effort, this thread wouldn't be here. The transmission shift control needs improvements as well...

 

[rossmon1]

If the speed set (with CC) is somewhat more (more then 3 or 4 mph) then your current speed, most CCs will downshift to reach the set speed ASAP. Any load or upgrade will trigger the downshift quicker. This is normal for most CC. Every vehicle I've owned has done this.


It is easy to justify the toys cc behavior with reference to design notes and i'm not saying you are wrong, whats wrong about its implementation on my 4runner is that it jars into the downshift when it doesn't need to as the vehicle is accelerating, not bogging and i was in 4th not Drive which is where i usually have it in hilly country or twisty roads. So it jumps into 3rd gives it the gas and then keeps going past the set speed by 2-5mph and thats not good on twisty roads.
Now i know somewthing about what to expect from CC systems and I used to install and adjust them for an auto specialty business. The way mine is working will be broiught up at my next visit to Toyota service.

 

[sharp4runr]

and thats not good on twisty roads. [/B]

Cruise control shouldn't be used on twisty roads anyways. I deactivate mine when the road conditions do not fit the use of it.

 

[Koz]

This is the same canned CC routine that many cars have had for many years. If Toyota had really put in the effort, this thread wouldn't be here. The transmission shift control needs improvements as well...

You are correct about routine CC. All CC that I have used work the same way. I think CC was designed to be set at your current speed and to bump it up or down a couple mph, not trying to maintain hills in high gears and twisty roads. For that matter, there will be lots of issues in the snow.

With that said, yes, it would be nice if it were a little smoother. Maybe the radar guided CC will be put in the Runner and some of these issues will be addressed.

Koz

 

[Koz]

mistake

 

[lbrunner]

Yeah my first trip the wife was sleeping in the pass seat, cruise control set at 70 and hit a big hill entering the green mountains, it downshifted twice and with this new exhaust, startled my wife due to the exhaust noise! This Magnaflow is really not that quiet! And the CC did seem to act abrupty with two downshifts.