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Strange behaviour - standard cruise control


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Hi, I have the standard cruise control, not the adaptive cruise control and don't use it much but today I tried it out and noticed the following.

 

Was travelling down the motorway with cc off. Then came to some roadworks and a 50 speed limit, traffic was not too bad so I set the cc to 50 (sorry for holding everyone up). After a while I could feel the car pulse faster and slower although the speed on the speedo seemed to stay the same. I put it in sport mode to see what the rev counter was doing and it was steady at 1500 rpm.

 

I noticed the power meter was raising slightly and then dipping so had a look at the Battery, engine, motor graphic. I noticed that when the car felt slower it was charging the Battery and when faster, the engine and motor were on. The Battery was full (most bars). It seemed that the car kept topping up the Battery and then discharging the Battery to assist the engine, but only for a few seconds at a time. It was a bit disconcerting and not a smooth drive.

 

If I hadn't come to my junction and turned the cc off, I would have anyway, as the ride was not smooth.

 

Has anyone else noticed this strange behaviour?

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I often use the CC through 50mph roadworks (just standard CC on mine like yours) and never had any problems like you describe. The car can be on the edge of running in EV at that speed and can drop in and out of EV with slight changes in incline - wonder if that was the problem? 

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It wasn’t dropping into EV, the ICE stayed running.

Just going into regen and power, as if the motor generator kept swapping between motor and generator. Motorway was flat and it cycled every few seconds.

It was as if it was trying to keep the speed but was oscillating, slow down speed up slow down speed up. Like a PID controller that was not tuned (if you know what that means).

Thanks
Paul

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I pretty much drive on cruise control whenever I can.  I have felt a very small transition/pulses between the speeds on downhill stretches, where the car is between rolling and needing power, only ever is those very rare situations, otherwise perfectly smooth.  

Was you situation like this?

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My experiences are along the same line as darrude, only occasionally have I felt anything other than a smooth ride.

In a conventional car, the  CC  would vary the engine speed to maintain road speed, in a hybrid the system would probably leave the ICE at a constant speed whilst varying the electric side of things to "trim" the speed, in my experience this is done quite well.

You can set the car so the rev counter is on in All modes, I did this for a while, interesting to watch the ICE switch off as you waft along the road.

 

Vince

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Had another play with this yesterday through some 50mph roadworks near us - it was a bit busier so couldn't use CC for as long as I would like but all the times I had it on 50mph was maintained and the car was perfectly smooth

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I tried it at 70 mph and it did a similar thing, I then turned the CC off and watched the charge/discharge cycle and it seemed to do the same, but you don't notice the affect. Perhaps you subconsciously adapt by pressing the accelerator more - man and machine in perfect harmony.

I wonder if the CC needs to learn how to control the car, and as I don't use it much it hasn't learn the right adjustments yet.

 

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5 hours ago, PaulWhitt20 said:

I tried it at 70 mph and it did a similar thing, I then turned the CC off and watched the charge/discharge cycle and it seemed to do the same, but you don't notice the affect. Perhaps you subconsciously adapt by pressing the accelerator more - man and machine in perfect harmony.

I wonder if the CC needs to learn how to control the car, and as I don't use it much it hasn't learn the right adjustments yet.

 

I use the CC a lot on motorways and have left it on for many miles of cruising. Usually have the car in Eco when travelling like this. Always totally smooth and extremely relaxing. If you are under warranty still, worth asking Lexus to investigate? 

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12 hours ago, wharfhouse said:

I use the CC a lot on motorways and have left it on for many miles of cruising. Usually have the car in Eco when travelling like this. Always totally smooth and extremely relaxing. If you are under warranty still, worth asking Lexus to investigate? 

Thanks for the suggestion, I have just taken out the extended warranty, but as I don't use the CC much I am not sure it is worth the hassle of taking time off work to take the car to Lexus. May mention it at the next service. There have been mention of similar issues on Prius and Hyundai Hybrid forums.

 

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