GS450h 'Hybrid PWR' and 'Sport' buttons

Ziggy1024 · February 5, 2020

This has been bugging me since I've had the car! Does anyone have a definitive answer as to what the 'Hybrid PWR' and 'Sport' settings on my car (a 2010 GS450h) actually do? And whilst we're at it, what about the 'S' mode on the transmission too?!

I've read lots of anecdotal, often conflicting statements and I know what general effects they have (make it 'faster' etc.!), but what's behind that?

E.G:

What does the 'sport' mode adjust on the shocks? Just compression damping or...?
Apart from the suspension (and steering), does sport mode just change the throttle map or is there any more to it than that?
I rarely use it, but 'Hybrid PWR' appears to maintain more charge in the Battery (to avoid the situation where it can't assist, I'd guess!) - what else?
Is the throttle map when both 'sport' and 'Hybrid PWR' are selected together, the same as when one or the other is selected?

You get the gist - anyone have any technical documentation on any of the above? John @Britprius, you seem to know pretty much everything about everything?!

Cheers! 😎

Britprius · February 5, 2020

Jon.
I think you have virtually answered your own questions.
Sport mode alters the throttle map, alters the effective gear ratio by going to and holding lower effective gears. Reduces the turns of the steering lock to lock, and stiffens up the 17 position variable shocks.
I use the term "effective gear ratio" because generally the ratios are nothing more than a balancing act of two electric motor generators. The is a real ratio change to the larger of the two motors rated at 180 hp to reduce it's maximum speed. This happens at around 60 mph + depending on load to reduce the speed of the motor, and increase it' torque. Electric motors of the type used have maximum torque at zero rpm.
Hybrid power increases the maximum current allowed to, and from the hybrid Battery, but constant use is not good for the Battery longevity as this gives rise to more heat being produced in the Battery.

I hope this helps.

John.

Ziggy1024 · February 5, 2020

Great stuff John - thank you!

Hope you don't mind my asking, but how do you know this stuff? I'm an engineer - I'd love to get stuck into the details but I've not found any good sources of info (apart from people like you!).

& I have to ask - '17 position variable shocks' - how are those 17 positions selected between?!

Britprius · February 5, 2020

16 minutes ago, Ziggy1024 said:

Great stuff John - thank you!

Hope you don't mind my asking, but how do you know this stuff? I'm an engineer - I'd love to get stuck into the details but I've not found any good sources of info (apart from people like you!).

& I have to ask - '17 position variable shocks' - how are those 17 positions selected between?!

On top of each shock absorber there is a stepper motor and this selects one of the 17 possible positions available. In normal mode the setting is chosen by the computer depending on your driving style. The shock absorber chrome shaft is actually a tube that contains a shaft that alters the valves in the piston assembly. This is the reason these shocks on the GS450H are close to £300 each.
I am now retired, but I was an electrical engineer, but also was qualified in, hydraulics, pneumatics, and mechanical engineering. I specialised in industrial automation, and robotics. This mean I went into all sorts of industries, and processes from food to nuclear to white goods,cars, and the Royal mint.

John.

Ziggy1024 · February 5, 2020

4 minutes ago, Britprius said:

On top of each shock absorber there is a stepper motor and this selects one of the 17 possible positions available. In normal mode the setting is chosen by the computer depending on your driving style. The shock absorber chrome shaft is actually a tube that contains a shaft that alters the valves in the piston assembly. This is the reason these shocks on the GS450H are close to £300 each.
I am now retired, but I was an electrical engineer, but also was qualified in, hydraulics, pneumatics, and mechanical engineering. I specialised in industrial automation, and robotics. This mean I went into all sorts of industries, and processes from food to nuclear to white goods,cars, and the Royal mint.

John.

Ah, I'd assumed it was a simple hard/soft selection - rather more satisfying that it isn't!

Have you 'just' reverse engineered your knowledge here then John, or have you had access to any tech info from Lexus?

Britprius · February 5, 2020

1 minute ago, Ziggy1024 said:

Ah, I'd assumed it was a simple hard/soft selection - rather more satisfying that it isn't!

Have you 'just' reverse engineered your knowledge here then John, or have you had access to any tech info from Lexus?

I must admit as far as the GS450H shocks themselves go I did do some reverse engineering, but not on the stepper motors. I was a very small part of a research team on hybrid systems with Toyota. However I am naturally curious on all things mechanical, and electrical, and like to try and keep up with technology.
Have you read up on how the Toyota/Lexus hybrid transmission works? If not I suggest you do as it is a real eye opener. It is so brilliantly simple. The basic system has no neutral no gear ratio changes, and no reverse, but accomplishes all three.

John.

Ziggy1024 · February 5, 2020

24 minutes ago, Britprius said:

I must admit as far as the GS450H shocks themselves go I did do some reverse engineering, but not on the stepper motors. I was a very small part of a research team on hybrid systems with Toyota. However I am naturally curious on all things mechanical, and electrical, and like to try and keep up with technology.
Have you read up on how the Toyota/Lexus hybrid transmission works? If not I suggest you do as it is a real eye opener. It is so brilliantly simple. The basic system has no neutral no gear ratio changes, and no reverse, but accomplishes all three.

John.

Fun, isn't it! Certainly interesting from a technical perspective - I have read everything I could find, there just doesn't seem to be all that much out there. That's taken some getting used to given that I could write my own ECU maps for my last car - I do like to get stuck in!

What about 'S' (sequential? sport? who knows!) on the transmission then? Additional engine braking and (to some extent) holding onto a higher 'gear' at low speeds seems to be the extent of it...

Britprius · February 5, 2020

5 minutes ago, Ziggy1024 said:

Fun, isn't it! Certainly interesting from a technical perspective - I have read everything I could find, there just doesn't seem to be all that much out there. That's taken some getting used to given that I could write my own ECU maps for my last car - I do like to get stuck in!

What about 'S' (sequential? sport? who knows!) on the transmission then? Additional engine braking and (to some extent) holding onto a higher 'gear' at low speeds seems to be the extent of it...

The S stands for sequential mode. This when used to "change down" increases the output of MG1 "used as a generator" , and charges the Battery at a high rate, and so gives some braking, but because of the position of MG1 in the transmission it also forces the engine revs to rise giving the appearance that the engine is braking the car when in essence the revs rising is a by product of loading the rotation of MG1. This is also how the engine is started while the car is on the move. If the car is stationary, and the engine is required to start MG1 is used as a starter motor.
It is also interesting to note that while the car is on the move MG1 can be running in either direction depending on road, and engine speed. MG2 is effectively fastened to the wheels. If the wheels are going round so is MG2.
MG2 gives reverse gear by being powered backwards from the Battery. If the Battery is low however the engine starts from MG1 then drives MG1 to produce power for MG2, but because of the way the system is configured the engine tries to move the car forwards against the drive of MG2. The Prius had problems reversing up steep slopes if the engine started because of this.

John.

Ziggy1024 · February 5, 2020

3 minutes ago, Britprius said:

The S stands for sequential mode. This when used to "change down" increases the output of MG1 "used as a generator" , and charges the battery at a high rate, and so gives some braking, but because of the position of MG1 in the transmission it also forces the engine revs to rise giving the appearance that the engine is braking the car when in essence the revs rising is a by product of loading the rotation of MG1. This is also how the engine is started while the car is on the move. If the car is stationary, and the engine is required to start MG1 is used as a starter motor.
It is also interesting to note that while the car is on the move MG1 can be running in either direction depending on road, and engine speed. MG2 is effectively fastened to the wheels. If the wheels are going round so is MG2.
MG2 gives reverse gear by being powered backwards from the battery. If the battery is low however the engine starts from MG1 then drives MG1 to produce power for MG2, but because of the way the system is configured the engine tries to move the car forwards against the drive of MG2. The Prius had problems reversing up steep slopes if the engine started because of this.

John.

I'll just draw that on a whiteboard...!

Sami Tilander · February 6, 2020

Search for "Prius Power Split Device" (PSD) for more information. One example here:

http://eahart.com/prius/psd/

(requires Flash, but explains quite nicely the function of the PSD)

BR.Sami

Sami Tilander · February 6, 2020

And if you really want all the nasty details, check this Technical Report: "EVALUATION OF THE 2008 LEXUS LS 600H HYBRID SYNERGY DRIVE SYSTEM"

https://www.osti.gov/servlets/purl/947393

It is for LS600h, but GS450h is quite similar (as far as I know)...

BR.Sami

LexIS200Sport · February 6, 2020

2 hours ago, Sami Tilander said:

Search for "Prius Power Split Device" (PSD) for more information. One example here:

http://eahart.com/prius/psd/

(requires Flash, but explains quite nicely the function of the PSD)

BR.Sami

2 hours ago, Sami Tilander said:

And if you really want all the nasty details, check this Technical Report: "EVALUATION OF THE 2008 LEXUS LS 600H HYBRID SYNERGY DRIVE SYSTEM"

https://www.osti.gov/servlets/purl/947393

It is for LS600h, but GS450h is quite similar (as far as I know)...

BR.Sami

Lovely, thanks for sharing these 🙂

Ziggy1024 · February 6, 2020

Thanks - I've read that doc, but hadn't seen the first link.

Britprius · February 6, 2020

eahart .com has possibly the best depiction of the basic Toyota transmission. I have recommended it for many years. It has however become more difficult to open the page fully as you now need to enable Adobe flash each time you use the page.
Using the sliders on the nomograph at the bottom of the page rely shows how the MG's work particularly MG1. It is not very apparent, but the engine drives the stubs on which the planet gears sit powering them in orbit around the central sun gear. It also shows the phenomenon of the engine inhibiting reverse operation if it is running.
It will be noted that MG1 can go from -6500 rpm to +6500 with the car moving forwards. This is for the gen1 Prius. The gen2 Prius had different gear ratios in the planetary gear set, and MG1 was able to run from -10,000 rpm to +10,000 rpm. After the gen2 from 2009 most transmissions were fitted with a second planetary gear set between MG2 and the ring gear that drives the wheels via the diff. This was to reduce the speed of MG2, and increase it's torque. It also reduced the possibility of the magnetic rotor exploding due to centrifugal forces at high speed.
There are now even later iterations of the system using more gear sets. In each version there has been a significant improvement in efficiency.

John.

steve2006 · February 7, 2020

This sounds more complicated to understand than the function of a basic PN junction diode, with electron flow being the opposite way to conventional current flow and electrons falling into holes I have now booked a holiday to Lanzarote to recover and relax 😀

Britprius · February 7, 2020

1 hour ago, steve2006 said:

This sounds more complicated to understand than the function of a basic PN junction diode, with electron flow being the opposite way to conventional current flow and electrons falling into holes I have now booked a holiday to Lanzarote to recover and relax 😀

Can I come?

John.

Ziggy1024 · February 11, 2020

There's a reasonable chance that anyone who's read this far will be interested in the mechanism behind VGRS too; this is a fairly concise summary:

https://www.autozine.org/technical_school/traction/Steering_2.html

LexIS200Sport · February 11, 2020

Risk of being unpopular, but hear me out 🙂

Reading all the tech shared here, I feel that the GS450h is truly an amazing car. Its hybrid powertrain is genuinely a work of art in my opinion. Its refinement and ruggedness is this car's single biggest USP. My car is 12-years old, has travelled 130k miles, regularly does lengthy cross-country journeys and wants for nothing but fuel in its tank and air in its tyres. I'm not sure of any other petrol cars in its class and vintage that can achieve regular 37 mpg and occasional 5.7 secs to 60 😉.

I also found out that a fully loaded JDM GS450h, in addition to radar cruise control, also featured Lane Keep Assist and driver alert monitoring!

The implementation of VGRS and AVS, however, leaves much to be desired. It feels like technology for technology's sake and they were rushed to production before they were perfected. These systems, being as complex (and expensive to replace) as they are, achieved neither the comfortable ride nor the sporty handing that they could have offered, in my opinion. A Jaguar XF of similar vintage, to me, rides and handles notably better without any active steering or dampers.

I'd even go as far as saying that my IS200, whilst certainly handled way better, also rode better than my GS, which just had all four shocks replaced. Lexus could have made the GS a masterclass in chassis engineering with these systems, but alas.

In normal driving mode, the steering has too much turn lock-to-lock. Great for the motorway but not so much for twisty country roads. Yes, flick the Sport button on and the steering tightens, but so do the dampers, and the car becomes comically stiff. I say comical because the interior, which in the 3GS is often prone to creaking and rattling in normal mode, really goes to town in sport mode 😄

Maybe it's just my car, being a Jan 2007 GS450h and thus an early production model. I heard things got refined along the way - 2008 facelift cars have different part numbers for the shocks, so maybe the ride and handling improved later on. I've also not driven a 3GS with APSSS so maybe Lexus nailed it with those cars. The APSSS also happens to be very expensive to replace and seem to last as long as the AVS shocks!

Farqui · February 12, 2020

Hi Ganesh @LexIS200Sport, it's good to hear your thoughts and I look forward to seeing how unpopular you become! 🤣

Seriously though, my GS road very badly initially and at that time I'd completely agree with your comments on the ride. However over my 3 years/30k+ of ownership I've ignored a stealers recommendation to replace perfectly serviceable dampers, had 4 wheel tracking sorted (the rear tow adjusters were toast), changed all 4 tyres and increased the tyre pressures.

In Normal mode now, the car now rides really well and is only crashy on really bad roads, as you'd expect. The front tyres had lots of tread remaining but had feathered badly, were very noisy so needed replacing and the 4 wheel tracking appears to have fixed the poor wear pattern. It's much more stable now and doesn't need constant steering adjustments. The new tyres appear to have softer side walls so need a few more psi to run comfortably, otherwise they bang/crash. Perhaps you should look at adjusting your tyre pressures a little? I'm monitoring tyre wear to ensure it's even across the tyres.

I haven't tried Sport mode recently but agree that it firmed the ride far too much on my earlier set-up, I'll experiment and let you know how it feels now.

Where are your creaks coming from? I've read that some owners suffer with creaks around the windscreen, maybe this is an issue on earlier cars too? My center console was terrible but was easily fixed and silenced with some felt over the clips.

I haven't noticed any issues with lock, so maybe you are right about subtle face lift changes?

Cheers, Lee

Ziggy1024 · February 12, 2020

12 hours ago, LexIS200Sport said:

I'd even go as far as saying that my IS200, whilst certainly handled way better, also rode better than my GS, which just had all four shocks replaced.

Blame all the pies. 500kg is a lot...

You're not wrong in general though and too I wish there were separate controls for the 'sport' parameters rather than lumping them all in together. My car (2010 on 17" wheels) doesn't ride as badly as it seems some do in sport mode; it's the agressive throttle map that I could do without.

LexIS200Sport · February 12, 2020

57 minutes ago, Ziggy1024 said:

Blame all the pies. 500kg is a lot...

But pies are supposed to be good at least for the ride comfort side of things, no? All those extra mass that the road undulations need to perturb...

57 minutes ago, Ziggy1024 said:

You're not wrong in general though and too I wish there were separate controls for the 'sport' parameters rather than lumping them all in together. My car (2010 on 17" wheels) doesn't ride as badly as it seems some do in sport mode; it's the agressive throttle map that I could do without.

Indeed, if the VGRS ratio and AVS stiffness could be decoupled, things would be amazing. I wonder if it is possible to "trick" or modify the VGRS so that it defaults to a quicker ratio, via Techstream or some other hardware/software mods...

The steering ratio that you get from Sports mode is pretty good actually. The feedback that you get from the road appears to be better too.

LexIS200Sport · February 12, 2020

Lee @Farqui, thanks for sharing 🙂

I've had mine for 5 years and almost 50k, and it's been fairly consistent throughout. The new shocks seem to have improved the ride comfort a little, and the car feels less floaty at higher speeds. Mine certainly needed replacing as the NSF and OSR shocks had been leaking quite badly. There was also a knocking noise coming from the rear shock. I replaced all four as I figured it was only a matter of time before the other two leaked as well. This is when I found out that cars before and after 2008 had different part numbers for the springs and shocks.

I'm running Pirellis all round, at the default tyre pressure (35psi). Wheel alignment has been maintained by WIM over the years, and the car is generally pretty stable on the motorway, even with the heavy winds lately. Might experiment with different pressures as you mentioned.

Interior rattles occur at various spots and come and go depending on the outside temperature. There is one set of rattles for winter and another for summer 😄. The sweet spot for this car seems to be 18 deg C (almost no rattles). I have fixed several along the way, such as the glovebox door rattle and rear power shade rattle, but just continue living with the others (very minor) 🙂

Sherra · February 15, 2020

sorry to hijack but Lee where in Notts did you get your tracking done after all the work you did on it? Mine is getting ready but not happy with Lexus Nottingham.

Paul

Farqui · February 15, 2020

sorry to hijack but Lee where in Notts did you get your tracking done after all the work you did on it? Mine is getting ready but not happy with Lexus Nottingham.
Paul

Hi Paul, no problem at all. Sorry to hear that Lexus Notts weren't up to snuff for you tho. Do you still have tyre wear or tracking issues?

My 4 wheel alignment was done at ETS in Mansfield, who did a great job and were very accommodating when we found that my rear track adjusters were locked up.

They were a bit of a trek for me vs my local Newark outlet but the Mansfield branch came highly recommended by a pal who builds cars (with fully adjustable suspension) and he won't use anyone else.

Let me know how you get on.

Cheers, Lee

Sherra · February 15, 2020

Thanks Lee

Not causing an issue yet just a gentle gut feeling that its ready for attention. As I'm just outside Mansfield it will be easy for me to get to Sutton when I do get it checked.