Dim witted AWD?

[///MAZI]

How does the AWD system work in the 4th Gen (facelift) Rav 4 Hybrid? My car seems to wheelspin now and again when pulling away if I give her the beans. I seem to think the rear wheels only come into play when she is running in EV mode??

We have just had our first snow and it will be interesting to see how she copes, seems to behave like FWD drive to me.

 

[philip42h]

The RAV4 AWD system has been designed to be quite smart throughout the generations - though to be fair I have no practical experience of the 4.4 hybrid AWD. The 'intelligent' AWD philosophy has been that the car will always set-off in AWD, reverting to FWD once safely underway ...

The blurb on the 4.4 hybrid states:

How does Toyota E-Four work?

In normal driving, all of the car’s power is sent through the front wheels as this is the most fuel-efficient use of energy – but the RAV4’s electronic control unit (ECU) constantly detects and analyses information such as vehicle speed, accelerator angle and wheel speed to calculate the optimum spread of torque. When it detects a need for more torque at the rear (for instance if the front wheels are slipping), it uses the rear motor to send power to the rear wheels and deliver extra shove.

In total, up to 60% of the car’s total power can be sent to the rear axle. So when you’re pulling away, going up a hill or driving on a low-traction surface such as wet grass, having more power sent to the rear wheels makes it easier to set off in a controlled way.

The E-Four system also ensures that wheel slip is suppressed, giving you confidence even when negotiating slippery or icy roads.

On top of all that, the system can deliver more power to the rear to deliver a sportier drive – giving a smoother, more direct cornering feel.

Which isn't inconsistent with that philosophy but perhaps leaves room for the 4.4 hybrid AWD to wait for slip to be detected at the front before applying power at the rear - maybe?

Otherwise, you might want to look at the state of your tyres and / or the quantity of 'beans' being applied ... 😉 

[anchorman]

The car is dim witted?  Depends what tyres you have on it and that’s down to you not the car.

[///MAZI]

Thats not really the point.

You could go through snow with a 2wd car with snow tyres on.

How does the rear axle come into play if the hybrid Battery is depleted??

No propshaft to take power from engine so the rear relies only on hybrid Battery.

That said she seems to have coped ok in the snow today, I did see lots of cars stuck.

[forkingabout]

1 minute ago, ///MAZI said:

How does the rear axle come into play if the hybrid battery is depleted??

 

The hybrid system wouldn't allow that situation to happen. 

[philip42h]

18 minutes ago, ///MAZI said:

Thats not really the point.

You could go through snow with a 2wd car with snow tyres on.

How does the rear axle come into play if the hybrid battery is depleted??

No propshaft to take power from engine so the rear relies only on hybrid battery.

That said she seems to have coped ok in the snow today, I did see lots of cars stuck.

The hybrid Battery is NEVER depleted - by design. There is ALWAYS sufficient power to drive the electric motors - which is essential if you want to go backwards. There is no reverse gear in the design of the hybrid system - the car is driven backwards by running the electric motors in reverse.

If the hybrid Battery is getting low, the engine fires and runs MG1 as a generator to charge the Battery and run MG2 and MG3 as necessary.

The 4.5 hybrid AWD is pretty much unstoppable - under realistic conditions and if driven 'sensibly' and shod with decent tyres.

The only potential issue for a 4.4 hybrid would be the design logic of the early E-FOUR AWD system as to whether it 'waits' for wheel spin at the front before applying power to the back, or sets-off in AWD (as every other RAV4 AWD does).