CVT and cruise control


#1

I just got back from my summer road trip in my 14 Subaru Legacy. Normally I do not use cruise control unless my foot or leg gets really tired or painful. I noticed something unusual. I’d be cruising along at a set speed on flat ground, say 2400 rpm at 80 mph and if I turn on the cruise control, within a minute or so, the tach would jump up to 32-3400 rpm. If I shut off the cruise control and held the same speed, I’d be back down to 2400 rpm. The only way to control this was to put the transmission in manual and use the paddle shifter to make sure I was in he 6th gear range.

Has anyone else noticed this behavior with a CVT in cruise control? I also found that when I would hit the resume button after dropping a little speed from using the brakes, the throttle would go WOT and the tack would go almost to redline until the car got back up to speed. Never had a cruise control do that before.


#2

huh? “make sure I was in he 6th gear range” ? This is a CVT, it has no gears.

Or do you have a car with “psuedo” gears programmed into the CVT software? Can you disable this?

I have a Subaru with CVT and never had this problem.


#3

It has paddle shifters so it has “Psuedo gears” programmed into the transmission. The only way to disable it is to put the shift selector into the manual position, otherwise the transmission changes to a lower ratio a minute or so after the cruse is engaged. It does this gradually so you don’t feel it, you just notice that the engine is running at a higher rpm.


#4

Why not put it in manual mode when using cruise control ? The “Psuedo gears” aren’t useful in CC.


#5

I do use the manual position when I use cruise control, but it seems odd to me that the transmission would behave differently in cruise control.


#6

That is odd. I’d post it on a Subaru forum, see if others have noticed this. Typically, high rpms reduce economy.


#7

My 2010 Insight would seem to do this, but I realized I’m not too good at knowing if the road were truly flat. Also, I was surprised to find out that my paddle-shifted 7th (high) is not as high as automatic “high.”


#8

I have a good friend in his 70’s with a new Civic with a CVT. He hates the way it acts. When he floors it to pass, instead of shifting down it simply maintains the optimum engine speed as the car accelerates. Yeah, the engine’s revs increase, but not the same way as a traditional tranny.

I’ve yet to meet anybody who has driven a CVT who actually likes it. :stuck_out_tongue_closed_eyes:


#9

@keith I suspect it’s a problem with your car. My Jeep Compass CVT (without the pseudo manual option) doesn’t do that - it does vary the RPMs at a set speed in response to extra load like hills or whatnot, but otherwise stays in the same range.

@the_same_mountainbik (dude, you lost your e!) I didn’t think I minded the CVT that much until my car was in the shop one day and I got to drive a Dodge Avenger. Same engine, regular auto. Just regular city driving feeling the engine go up and down the gears was a revelation. CVTs are no fun.


#10

CVTs may be less fun, if you like to hear your engine RPMs going up and down, but a CVT will maintain the proper RPM for the speed and the power needed. If you floor it, the RPMs will go up to a high value and stay there as the gear ratio changes, for maximum power. Frankly, I don’t know what that high value is, I’ll have to do a test run. But I suspect it is at the max torque point.

Frankly, the software that lets a CVT seem to imitate a conventual auto transmission is, to me, silly. All you are doing is increasing the wear on the transmission, decreasing the acceleration, all just so it sounds the way you like.

Consider an electric car, which we may well all be driving in a few decades. Will the manufacturers add an option so you can hear an engine shifting gears as you accelerate? Even more silly.

b


#11

It would be at maximum power output of the engine.


#12

As with everyone else answering so far ; My 06 Escape hybrid maintains highway speed and the engine RPMs rise or fall as needed due to terrain.
For yours to be in constant high RPMs seems to me like a fault of just that car . . perhaps in the manner you have selected to use it.
When we first got our Escape hybrid it drove my wife nuts till I re-explained enough that ‘‘The battery drives the car . . the engine charges the battery . .the engine has a mind of its own so forget about what the engine is doing in THIS car.’’ . . it finally sunk in and now she doesn’t even notice it.
As for other CVTs, I’m not familiar with those but from these other posts . . . . .


#13

Just to clarify the issue, when I am not on cruise control, the engine will vary a little depending on the terrain. The problem is when I turn on the cruise control, that variation is amplified and the engine runs at a generally higher RPM, quite a bit higher. Higher than the terrain would justify. Its as if the programming of the transmission changes when cruise is engaged.

I don’t use cruise control very often so I just now noticed it doing this.


#14

That’s got to be either the way they programmed them in '14, or else a fault in the engine control module. Our '16 O’back does not do that, and I use CC alot.

(I have to agree with those who don’t like CVT. I knew what we were getting, but the O’back’s attributes outweighed the negative of having CVT. Having driven vehicles w/o the fake shifts, I’d rather have them - silly as they may be - than listen to the engine acting like it’s attached to a rubber band.)


#15

I had a 2005 Dodge Dakota with a 5 speed automatic and cruise control. I was doing 55 mph with the cruise control on and negotiated an abrupt incline for a bridge. At the actual bridge surface I caught a slight bit of air. The vehicle over-revved badly and when it landed it lunched the torque converter. I sold that vehicle several years later and bought a 2015 Jeep Cherokee. While on the freeway with the Jeep I was using the cruise control in a slight drizzle when the cruise control automatically turned off and the vehicle started braking suddenly.

All that said to say this: the common denominator in both instances was a loss of traction by the drive wheels. I did some research and spoke with some mechanics. Apparently, in modern vehicles when the computer detects a loss of traction in the drive wheels it sends a signal to the cruise control to do…something. I was advised you should never use cruise control either on a bumpy road or in any kind of wet because the computer thinks the vehicle is not travelling at the correct speed and takes “corrective” action.

In your case, did you by any chance happen to hit a bump which caused one of your drive wheels to temporarily leave the ground?


#16

Thanks Macfisto. Calling all E’s, calling all E’s!!
Seriously, I lost it to software limitations. It’s funny really, my label has too many letters, but if I don’t put at least 20 letters in my post it won’t accept it! The software is apparently a bit schitzo! I don’t miss my E. Its loss is a good conversation piece. :stuck_out_tongue_winking_eye:


#17

No, in all cases I was cruising on an interstate.


#18

How did this end up here?


#19

Roger that. Just bringing up a possibility.


#20

@Dakotaboy It is never a good idea to put your real name and email on an open web site. You should edit them out.