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Discussion Starter · #1 ·
Noticed that if car is in "park" and you select sport mode you can rev the engine a little bit and the rev counter moves up. Previous autos I've had didnt allow you to do this. I know you can rev it in neutral but find it strange you can do it in park.

Anyone else found this or know why this might be?
 

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If I'm reading your post correctly, are you saying that all other cars you've owned, when you step on the accelerator with the gear in Park, the tachometer doesn't move?
Hmm... strange. All cars I've owned you can watch the RPM needle go up and down while in Park.
 

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All of the automatic transmission cars that I've ever owned let me rev the engine while in park.
 

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Discussion Starter · #4 ·
If I'm reading your post correctly, are you saying that all other cars you've owned, when you step on the accelerator with the gear in Park, the tachometer doesn't move?
Hmm... strange. All cars I've owned you can watch the RPM needle go up and down while in Park.
Yip, only had two autos before the CT so a bit of an auto newbie - manual is much more common than auto in the UK. Maybe I'm getting confused :confused: and looking for something thats new to me but is common to everyone else :)
 

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Yip, only had two autos before the CT so a bit of an auto newbie - manual is much more common than auto in the UK. Maybe I'm getting confused :confused: and looking for something thats new to me but is common to everyone else :)
I don't know but I've never seen a car that does what you described in my lifetime. I've rented/driven hundreds of vehicles worldwide, literally, and never seen any that behaves that way. In fact, merely starting the engine itself boosts the RPM needle up a bit.
Curious...which cars are you referring to that don't do that?
 

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Curious...which cars are you referring to that don't do that?
I have a 2007 Toyota Camry Hybrid that does exactly what the OP indicates. With car in park you can put the gas pedal all the way to the floor and the gas engine just sits at idle (assuming the gas engine is even running).

It doesn't have a tach so no gauge to look at. It doesn't have the EV/Normal/Sport selection so there's no different modes to try it in.

It does have N, but I can't recall ever trying to rev the engine while in N.
 

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Below is a brief explanation of how a CVT transmission works

A regular automatic transmission has a fixed number of gears. The number of gears, or speeds, is what gives a transmission the designation of four-speed automatic, five-speed automatic, etc. In contrast, a continuously variable automatic transmission has an infinite number of gears, made possible by a system of variable pulleys and belts. If it sounds complicated, that’s probably because it is.

So, what do the variable pulleys and belts mean to you? In a car equipped with a CVT there are no noticeable gear shifts like you would feel with a regular transmission. Anyone who has driven a regular automatic transmission knows that engine speed drops during the shift from first to second, third to fourth, etc. That drop in rpm during shifts can put the engine below the rpm range where it makes power; an engine makes its peak power at a certain rpm — 5,000 rpm, for example. In a CVT-equipped car, the drop in rpm never happens.

When you punch the accelerator on a CVT-equipped car, the rpm will rise to where the engine makes the most power, let’s say 5,000 rpm, and it stays there while the vehicle accelerates.

In other words the CT engine revs to the optimum RPM for the power needed at the time and situation encountered.

Obviously when the vehicle is in park there is no need for any power and no need for the engine rpm's to increase when the gas pedal is pressed. Remember the gas pedal is drive by wire - a potentiometer sends a signal to the ECU.

It is conceivable that the brain of the car (ECU) knows that if the car is in park no matter the position of the gas pedal there is no need to supply gas to the engine because power to drive the car is not needed. Hence no change in rpm.

I just tried the car in sport mode / park the engine went to 2500 rpm and wouldn't go any higher even with the gas pedal fully depressed. Then the engine stopped and the car displayed ev mode.
 

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Below is a brief explanation of how a CVT transmission works

A regular automatic transmission has a fixed number of gears. The number of gears, or speeds, is what gives a transmission the designation of four-speed automatic, five-speed automatic, etc. In contrast, a continuously variable automatic transmission has an infinite number of gears, made possible by a system of variable pulleys and belts. If it sounds complicated, that’s probably because it is.

So, what do the variable pulleys and belts mean to you? In a car equipped with a CVT there are no noticeable gear shifts like you would feel with a regular transmission. Anyone who has driven a regular automatic transmission knows that engine speed drops during the shift from first to second, third to fourth, etc. That drop in rpm during shifts can put the engine below the rpm range where it makes power; an engine makes its peak power at a certain rpm — 5,000 rpm, for example. In a CVT-equipped car, the drop in rpm never happens.

When you punch the accelerator on a CVT-equipped car, the rpm will rise to where the engine makes the most power, let’s say 5,000 rpm, and it stays there while the vehicle accelerates.

In other words the CT engine revs to the optimum RPM for the power needed at the time and situation encountered.

Obviously when the vehicle is in park there is no need for any power and no need for the engine rpm's to increase when the gas pedal is pressed. Remember the gas pedal is drive by wire - a potentiometer sends a signal to the ECU.

It is conceivable that the brain of the car (ECU) knows that if the car is in park no matter the position of the gas pedal there is no need to supply gas to the engine because power to drive the car is not needed. Hence no change in rpm.

I just tried the car in sport mode / park the engine went to 2500 rpm and wouldn't go any higher even with the gas pedal fully depressed. Then the engine stopped and the car displayed ev mode.
You are showing a traditional CVT. It has a primary shaft with a fixed cone and a sliding cone. The secondary shaft has a fixed cone and a sliding cone. There is a belt between the two shafts. Oil pressure adjusts the position of each cone and that gives you your infinitely variable ratios.

The Prius and CT200h actually are must more similar to a traditional automatic transmission. The main planetary carrier speed is controlled by an electric motor instead of various clutch packs, though. Controlling the speed of the motor controls the planet and ring gear speeds and thus the output shaft speed. I've torn apart both a traditional 6 speed auto and a hybrid CVT. The CVT is impressively simple. It really is brilliant. I'm sure the controls are very complex, but mechanically, it looks like it would have far fewer modes of failure just based on mechanical simplicity.

As far as why the engine doesn't rev over 2500 with the car in park, you are probably right. The ECU logic says "stop wasting gas, dummy" and limits the revs. :D
 

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You are showing a traditional CVT. It has a primary shaft with a fixed cone and a sliding cone. The secondary shaft has a fixed cone and a sliding cone. There is a belt between the two shafts. Oil pressure adjusts the position of each cone and that gives you your infinitely variable ratios.

The Prius and CT200h actually are must more similar to a traditional automatic transmission. The main planetary carrier speed is controlled by an electric motor instead of various clutch packs, though. Controlling the speed of the motor controls the planet and ring gear speeds and thus the output shaft speed. I've torn apart both a traditional 6 speed auto and a hybrid CVT. The CVT is impressively simple. It really is brilliant. I'm sure the controls are very complex, but mechanically, it looks like it would have far fewer modes of failure just based on mechanical simplicity.

As far as why the engine doesn't rev over 2500 with the car in park, you are probably right. The ECU logic says "stop wasting gas, dummy" and limits the revs. :D
Here's a link to more info than anyone probably needs to know regarding Toyota's HSD system.

Toyota Prius - Power Split Device
 
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