4WD system does not work, I chase Mitsu for solution.

[MartinH]

With over one year of experiense and first service done, I start chasing Mitsu for solution.
EVERY one know the system does not works, one Magazine in Sweden gave the PHEV grade 1 out of 5 for the 4WD system with short text "Does not work".
I also have problem using my car, I have a trailer loaded with a small Wheel loader, total weight 1530kg together.
I ofter have to use small roads, park on grass, snow, bad roads.
The system does not work, ONE! (i have never seen 2) of the front Wheels stars to spinn, you have to push the accelerometer more to get the back Wheel(Always only one) to start pushing. You do not know the front whelle is spinning until the window is covered in mud as you do not hear is spinning, and you can not see on the dash.
This results in that you are looking like a old lady in snow, one front wheel spinning like hell, spraying the whole side of the car with mud and snow before you start to move, if you can get it moving.
I asked Mitsu for soft ware update when service, no update avaliable.
I now chase the seller of the car, he has asked Mitsu in Sweden, the answer from them was very interesting, "you have to have full battery to get the power to the wheels as they consume 60kw each", idiots! (sorry) i do not need more than 10kw to get the front wheel spinning, what should i do with the 110 remaining?
It has nothing to do with the prower, it has do do with the distribution of the power to the wheels.

I chase Mitsu, I hope you also do to make them understand and correct the error.

 

[jaapv]

It is not a 4x4 offroader, it is a 4WD softroader and has no locking differentials.

 

[Steepndeep]

I think the 4WD lock function is bogus. Ok, the car has no diffs, but what should happen with 4WD lock activated is this. Either should SIMULTANEOUSLY one front wheel and one rear wheel start spinning. Key word is simultaneously, no delay between front and rear whatsoever. Or alternatively the car moves, with no wheels spinning or one wheel only spinning.

Neither seems to be the case. First one wheel start spinning, and then after further pressing the accelerator, one wheel on the other axel starts spinning. So 4WDlock is rather 4Wdslip.

 

[geoffshep69]

I think the 4WD lock function is bogus. Ok, the car has no diffs, but what should happen with 4WD lock activated is this. Either should SIMULTANEOUSLY one front wheel and one rear wheel start spinning. Key word is simultaneously, no delay between front and rear whatsoever. Or alternatively the car moves, with no wheels spinning or one wheel only spinning.

Neither seems to be the case. First one wheel start spinning, and then after further pressing the accelerator, one wheel on the other axel starts spinning. So 4WDlock is rather 4Wdslip.

Why should the front and rear wheels spin simultaneously ?

The 4WD lock button allocates power 50/50 to the front and rear, but if one axle has a different amount of traction to the other then isn’t is perfectly possible that one wheel would spin on its own ?

 

[anko]

In a normal car, you would think wheel speed (or axle speed) is synced between front and rear. As this would result in a transfer of power to the axle that still has grip.

In our case, power cannot be transferred, as each axle has it's own motor. so, it doesn't really matter wether wheel speeds (axle speeds) are synced.

60 kW front is rendered useless if one front wheel has no grip and is not braked.
60 kW rear is rendered useless if one rear wheel has no grip and is not braked.

 

[Steepndeep]

Well this really comes down to how the 4WDLock is intended to work, and how it is implementation is done.

My assumption was, based on Mitsu Ads, that it should mimic a centre locked diff. In that case the wheels should spin as I described previously.

Now if it really is a 50/50 power split we have an interesting situation. Suppose one wheel hangs in the air, then only almost 0 power goes through that Emotor. Does that mean that the other Emotor is capped to almost 0 power?? Hope not

However if 4WDLock really states that you will send the same "power request" to both motors and one wheel is in the air. Then you need to floor the pedal to get maximum power through the other Emotor while the the spinning wheel spins like crazy. On my Grand Vitara with locked center diff the car would move as soon as enough torque gets to the axel with both wheels on ground, and the wheel in the air would rotate with twice the speed of the wheels of the axel with traction. This is how I would like 4WDLock to work.

 

[maby]

In answer to the OP, there is no possibility of a software fix because there are physical components - the differential locks - missing that would be required to make it a proper 4WD. There may be some tricks that they could play with the ABS that could improve the off-road performance, but that will always be less than perfect. If they were to lock the spinning wheel on the brakes, they would also have to cut the speed of the drive to that axle since the wheel that still had traction would then be spinning at twice the speed. With the wheel locked stationary, it will be very difficult to determine when it has regained grip - and, when it does, it will be trying hard to stop the car moving!

 

[maby]

P.S. The RX450h addresses the same problem with three electric motors in place of the PHEV's two - each front wheel is driven separately giving the effect of a diff lock there.

 

[anko]

Now if it really is a 50/50 power split we have an interesting situation. Suppose one wheel hangs in the air, then only almost 0 power goes through that Emotor. Does that mean that the other Emotor is capped to almost 0 power?? Hope not

However if 4WDLock really states that you will send the same "power request" to both motors and ...

I think it is not a power plit, but a toruqe split. That will work out differently. Same torque, different RPM, different power. And if it does not work for you, simply turn it off :idea:

This is how I would like 4WDLock to work.

Is not going to happen, as we do not have the parts ...

 

[anko]

P.S. The RX450h addresses the same problem with three electric motors in place of the PHEV's two - each front wheel is driven separately giving the effect of a diff lock there.

As separate front and rear motors cannot replace a center diff lock, two front motors cannot replace a front diff lock, I would say

 

[maby]

P.S. The RX450h addresses the same problem with three electric motors in place of the PHEV's two - each front wheel is driven separately giving the effect of a diff lock there.

As separate front and rear motors cannot replace a center diff lock, two front motors cannot replace a front diff lock, I would say

Of course it can - the differential is just there to split the output of a single power source to drive two power sinks (the wheels) with an appropriate division of power taking into account minor differences in the circumference of each wheel. The problem comes when one wheel loses traction and robs the other of power leaving the car stranded. The locking or limited slip diff blocks this by blocking the differential action either completely or partially to ensure that the wheel that still has traction can continue to move the car. If each axle or wheel has its own power source, then there is no need for a locking differential - actually there is no differential at all. In the PHEV, each axle has its own electric motor and included a standard, non-locking differential. If both motors are run at 500rpm (for the sake of argument), then all four wheels will be rotating at 250rpm (again, for the sake of argument) assuming that the car is going in a straight line, a wheels are equally worn and they all have traction. If one wheel loses traction, then it will rob the other wheel on the same axle of power, but the other axle will still be receiving power from its own motor and its wheels will continue to turn. The PHEV, by default, seems to put more power down on the front axle than the rear - presumably to improve handling - and the 4WD Lock button just seems to adjust this power split to equalise the power distribution.

If all four wheels each had their own dedicated electric motor, then there would be no need for any differential locks - you could lose traction on three wheels, but the fourth would still be driven at 250rpm and could, in theory at least, keep the car moving. With sufficient sensors, it may even be possible to reduce the power directed towards the spinning wheels and direct more towards the one that still has grip.According to the literature, the RX450h has three motors - one each on the front wheels and a third at the rear - presumably coupled to a standard differential.

This is the way that many large earth-movers work - using hydraulic transmission. The petrol (diesel?) engine is coupled to a large hydraulic compressor which drives turbines on each wheel. Valves in the hydraulic lines control the distribution of power to each turbine and provide the differential effect.

 

[ian4x4]

This problem was discussed at great length in the 'towing a boat up a ramp' thread.
http://www.myoutlanderphev.com/forum/viewtopic.php?f=10&t=2676

I think we acknowledged that the trailer nose weight tended to relieve the front axle of traction, and then the amount of torque available to the back axle was limited. It's just the way the electric drive is designed, I'm sure it's good for normal road use, or light off-roading.

 

[anko]

P.S. The RX450h addresses the same problem with three electric motors in place of the PHEV's two - each front wheel is driven separately giving the effect of a diff lock there.

As separate front and rear motors cannot replace a center diff lock, two front motors cannot replace a front diff lock, I would say

Of course it can - the differential is just there to split the output of a single power source to drive two power sinks (the wheels) with an appropriate division of power taking into account minor differences in the circumference of each wheel. The problem comes when one wheel loses traction and robs the other of power leaving the car stranded. The locking or limited slip diff blocks this by blocking the differential action either completely or partially to ensure that the wheel that still has traction can continue to move the car. If each axle or wheel has its own power source, then there is no need for a locking differential - actually there is no differential at all. In the PHEV, each axle has its own electric motor and included a standard, non-locking differential. If both motors are run at 500rpm (for the sake of argument), then all four wheels will be rotating at 250rpm (again, for the sake of argument) assuming that the car is going in a straight line, a wheels are equally worn and they all have traction. If one wheel loses traction, then it will rob the other wheel on the same axle of power, but the other axle will still be receiving power from its own motor and its wheels will continue to turn. The PHEV, by default, seems to put more power down on the front axle than the rear - presumably to improve handling - and the 4WD Lock button just seems to adjust this power split to equalise the power distribution.

If all four wheels each had their own dedicated electric motor, then there would be no need for any differential locks - you could lose traction on three wheels, but the fourth would still be driven at 250rpm and could, in theory at least, keep the car moving. With sufficient sensors, it may even be possible to reduce the power directed towards the spinning wheels and direct more towards the one that still has grip.According to the literature, the RX450h has three motors - one each on the front wheels and a third at the rear - presumably coupled to a standard differential.

This is the way that many large earth-movers work - using hydraulic transmission. The petrol (diesel?) engine is coupled to a large hydraulic compressor which drives turbines on each wheel. Valves in the hydraulic lines control the distribution of power to each turbine and provide the differential effect.

When two motors on the front wheels give the same effect as a front locking diff, then one motor on the front axle and one on the rear axle can give the same effect of a center locking diff. But they can't, as power from the slipping wheel (or axle) cannot be routed to the non slipping wheel (or axle). That power cannot be redirected and is rendered useless.

I don't know much about earth movers with hydraulic transmissions, but I bet there is a single source of hydraulic pressure and this pressure can be routed to the wheel or track that has grip. So, when one wheel or track looses grip, you still have full power available. In the PHEV, when one axle uses traction, you loose half of the availabe power.

 

[maby]

...

When two motors on the front wheels give the same effect as a front locking diff, then one motor on the front axle and one on the rear axle can give the same effect of a center locking diff. But they can't, as power from the slipping wheel (or axle) cannot be routed to the non slipping wheel (or axle). That power cannot be redirected and is rendered useless.

I don't know much about earth movers with hydraulic transmissions, but I bet there is a single source of hydraulic pressure and this pressure can be routed to the wheel or track that has grip. So, when one wheel or track looses grip, you still have full power available. In the PHEV, when one axle uses traction, you loose half of the availabe power.

Well, it is true that the car is not able to reroute the power of the second motor to the axle that still has traction (or from one wheel to another), but that does not matter too much - the main purpose of the locking diff is simply to keep the vehicle moving. On Landrovers and Landcruisers which have the full compliment of locking mechanical diffs, they warn you to not operate them at wide throttle openings - these are mechanisms that you use gently at low power and low speed to regain traction. In that famous PHEV example that was posted here a few months ago, the vehicle was lightly loaded with no trailer on reasonably flat and dry terrain - it got stranded because it got cross-articulated with diagonally opposite wheels spinning. If it had had three motors, it would have got out fine because at least one wheel would have had sufficient traction and been able to put a few kW onto the ground to keep the car moving.

While it is true that in a traditional solution with mechanical locking differentials the full power output of the engine will be routed to whichever wheel still has traction, the drive train to that single wheel may not be designed to transmit so much power - if you have the vehicle loaded to the limit, lose traction on one or more wheels and engage the locks, still pushing the car hard, you risk breaking something - I've done it!

 

[anko]

We have also seen the example of a PHEV not being able to pull a boat + trailer out of the water. A locking center diff would have saved the day, two front motors would not have.

 

[maby]

We have also seen the example of a PHEV not being able to pull a boat + trailer out of the water. A locking center diff would have saved the day, two front motors would not have.

Once again it would all depend on how close to the limit you are pushing the vehicle. If it was designed to put 100hp down through 4 wheels and you end up putting most of that 100 through one wheel, then you could easily break something. When wheels start slipping, you need to reduce the demands that you are putting on the car.

 

[anko]

When wheels start slipping, you need to reduce the demands that you are putting on the car.

By 50%? That would mean the rear motor by itself would be capable of maxing out what the rear axle can handle. Can't imagine ....
Maybe, just 10 or 20% of the power of the front motor rerouted to the rear motor would have been sufficient to pull the boat out of the water. But even this 10 or 20% cannot be transferred.

 

[Trex]

With over one year of experiense and first service done, I start chasing Mitsu for solution.
EVERY one know the system does not works, one Magazine in Sweden gave the PHEV grade 1 out of 5 for the 4WD system with short text "Does not work".
I also have problem using my car, I have a trailer loaded with a small Wheel loader, total weight 1530kg together.
I ofter have to use small roads, park on grass, snow, bad roads.
The system does not work, ONE! (i have never seen 2) of the front Wheels stars to spinn, you have to push the accelerometer more to get the back Wheel(Always only one) to start pushing. You do not know the front whelle is spinning until the window is covered in mud as you do not hear is spinning, and you can not see on the dash.
This results in that you are looking like a old lady in snow, one front wheel spinning like hell, spraying the whole side of the car with mud and snow before you start to move, if you can get it moving.
I asked Mitsu for soft ware update when service, no update avaliable.
I now chase the seller of the car, he has asked Mitsu in Sweden, the answer from them was very interesting, "you have to have full battery to get the power to the wheels as they consume 60kw each", idiots! (sorry) i do not need more than 10kw to get the front wheel spinning, what should i do with the 110 remaining?
It has nothing to do with the prower, it has do do with the distribution of the power to the wheels.

I chase Mitsu, I hope you also do to make them understand and correct the error.

MartinH I have done a bit of using 4wd vehicles over the years for the harder conditions. But have never used the PHEV for the serious stuff yet. I have other vehicles for that.

But I would like to ask you what tyres are you using for your excursions. Are they "proper" 4wd tyres. I do not mean the tyres that come with the PHEV and I know you have winter tyres over there but from the pictures I have seen they are not what I call "proper" 4wd tyres for difficult conditions.

This is for everyone and is just my opinion, tyres are one of the most important ingredient for safe and successful on or off road travelling. Again IMO.

Diff locks, front and rear and centre ,are bloody nice to have certainly but the tyres, or to be more precise the type of tread pattern on the tyres, is more important. Again IMO.

Now I have not looked up what you can get for the PHEV in the way or "proper" 4wd tyres (they may be of a size that make it difficult ) but if the PHEV was the only car I owned, and was going into slippery or steep etc difficult conditions regularly with it, that would be the first thing I would do.

If I could not find the right tyres for the PHEV I would use chains on the tyres and have done so before. Here in Australia we can get the cheaper
"snow chains" or some serious "mud type chains" and others in between. You may think they are a hassle to fit etc but IMO they are less of a hassle than being bogged and having to be extracted by others or having to do it yourself. Even extracting yourself with a winch can be a hassle if you do not have a "easy" anchor point like a tree nearby. :lol:

But you people over there probably know all of this anyway.

Regards Trex

 

[Trex]

Ok this is a video I found from Allan Whiting here in Australia who is famous with 4wd fanatics here. I do not consider myself a 4wd fanatic. I just have to use them in my business, but even I have heard of him. :roll:

Note when he goes up his test incline.


https://www.youtube.com/watch?v=MIcsem1MEZY


Some of those washouts are pretty deep which is common on some of our tracks. But he picks his lines resonable well IMO and he mentions tyres.

I love it when he says "its not very happy " :lol: "it doesn't like this at all" :lol:

"but its doing it"

Does it beep like that when you have traction problems? :roll: or is it something else?

I have never heard it on mine. But like I have said before I have not taken my PHEV into difficult conditions yet.

That could be annoying. :lol:

Also notice what he does when he has cross axle problems like turning the front wheels.

I might not agree with all of his comments though. 8.4lts/100kms ( sounds a bit high to me :? ) is one of them.

ps and no we all do not talk that way here in Australia. :lol:

 

[AndyInOz]

Maaaaaaaaaaaaaaate, of course we all talk that way here...



I was wondering if the beeping was the parking sonar? I have the same model, and that is the most beepy aspect of the car.