Ziggy1024

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.

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

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

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...!

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...

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?

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?!

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! 😎

I suspect you're right - it's just the memory of having to do the job twice on the Jag (second time in the dark and the rain!) that makes me hesitate! You're right though; 'you get what you pay for' just isn't always true these days...

We had a 7 seat 626 back in the day - a 1990 626 'GT'. My old man had another 626 before that too - 1985 'lx' in blue with blue velour interior. 😎

Thanks John. So you've tried the non-name-brand ones then? They are certainly tempting at that price, but do they last more than 5 minutes? Bad memories of fitting cheap pattern wheel bearings on my XJ6 a few years ago...

Hopefully an easy one for someone - 3rd gen GS (mines a 2010 450h) front hubs:

Are they all the same? I.e. gs300,430,450h etc.?

Are NSF and OSF actually the same part?

Are they the same as on the IS too?

Just trying to find out what I'm looking for!

Cheers all.

Proof that the spanner fits:

@Farqui Yes, I decided that as it seems nobody else has ever seen one go wrong, a used one would be a safe enough bet! I believe a lot of GR-engined cars (is250, gs300 etc.) use the same pump, but as I didn't find definitive proof on that, mine came from another 450h!

So without wanting to count too many chickens just yet...

The HP fuel pump is easy to replace. Lexus quoted 1.3 hours which I guess is fair enough as everyone needs a tea break at some point (I don't actually have any complaint about their estimate - I understand what they need to cover!).

• Remove the air hose from the throttle body, or you can't get at some of the below - 10mm for the jubilee clip
• 2x 12mm nuts (pump flange to top end of engine) - no access problems for those, but you'll need a deep socket and an extension.
• 2x E8 studs - there is other pipework in the way if you try to remove the pump without taking the studs out
• 19mm spanner for the fuel connection closest to the back of the engine. You can get a spanner on there with enough clearance to turn it - persevere!
• Spring clip on the small fuel hose, quick (squeeze!) release on the remaining one and one electrical connector

Total about an hour including getting tools out, 'help' from a 7-year old and tidying up afterwards.

And yes, it seems to be working so far. 😎

I was only joking @Farqui !

I'm pretty sure that the issue is with the HP side. Dealer had identified the same candidates as Chris @Mihanicos above, but as far as I can tell concluded that the pump was more likely than the valve/relay based on previous experience.

Swapping the pump doesn't look too difficult (quoted at 1.3h labour) so given that I should be able to get a used one easily enough, I'm tempted to give that a go...

Oi, @Farqui ! Whatya doing, 'liking' my misfortune?! 🤣

@Mihanicos Chris, Lexus have come back as saying it's the HP fuel pump. I've not got their reasoning yet (and I'll do whatever I can to confirm it as per your recommendations above), but my initial thought is that I'll source a used one - they don't seem a common failure so at least they should be available and relatively affordable...  Any thoughts?

Next task is to research compatibility between years, or even other models.

Thanks again Chris!

I've actually just left the car with Lexus for a pre-arranged appointment (on another issue that they've been trying to resolve since the car was covered by the extended warranty!) - having a courtesy car for tomorrow will save me a lot of hassle, so I didn't want to cancel that. Clearly they'll have a look at this issue too, but if/when they want to start randomly replacing expensive parts, I'll get stuck back into your suggestions...

Cheers,

Jon

Is the 'fuel press' (kPag) that I've seen in techstream actually the low side reading?

1 hour ago, Mihanicos said:

The DTC occurs when the fuel pressure on the high pressure side is too low. Fuel pressure is achieved by a mechanical pump driven by a camshaft and is regulated by the spill control valve. A fuel pressure sensor monitors the pressure and is regulated between 4 and 13 MPa.

If the pressure is lower, the ECU closes the spill control valve. If the pressure continues to drop, the ECU blocks the power to the spill control valve so it remains open and regulates the engine to a max of 2000 rpm. 

Check for fuel leaks on all pipes of the fuel system after the high pressure pump. [ Fuel pipes to direct and indirect injection injectors. Fuel injectors leaking.] ]

Fuel pressure relief valve.

Fuel relief valve relay.

Fuel pressure sensor.

Fuel pump for high pressure.

To carry out some tests you will need the techstream.

Kindest regards,

Chris.

 

Thank you Chris! I can stop looking at the low pressure side at least, and looking for leaks is something I can manage! I do have techstream, although I'm definitely not an expert at using it yet... Are there some specific tests you'd run?

So who knows anything about what I should expect to see in the way of fuel pressure?

According to techstream, "Fuel Press" (kPag) is <200 when running, but when the engine (and fuel pump) shut itself off (after the hybrid Battery charged sufficiently), the value started gradually climbing. It went as far as 5200 after about 6 minutes, then started dropping again...

Is this increase normal, explained by e.g. heat soak into the now-stationary fuel at the rail, or is it potentially a sign that the sensor is playing up?

What should fuel pressure be with the engine running? Anyone else who could take a look at what their car (any 6-cyl GS/IS I guess) would be a hero!

5 minutes ago, Farqui said:

Well that is good news, that the filter is just under the rear seat.

The pump's under the seat - the filter is buried inside the pump assembly...

Well if nothing else, I've ascertained that changing the in-tank pump would take about 10 minutes! Popped it out for a look - hard to tell without dismantling it completely, but what I can see of the filter in the bottom looks fine, and the inside of the tank certainly looks clean. No great surprise given that the car's only done 60,000 miles, mind...

9 minutes ago, Hangie said:

Hi,

If it is faulty it can leak while in OFF hecne dropping the pressure. 

As far I'm aware there is only single pump in a tank. Then it is all plumbing 🙂

Yes, I appreciated that's what you meant - I just don't know how to go about testing it!

Does anyone have any reference fuel pressures? What should I be seeing?

WRT the number of pumps, there's also the high pressure pump (you might call it something else?) in the engine bay - I think (correct me, anyone?!) the engine can run on direct or port injection depending on circumstances, and wondered whether the problem could therefore be with whichever of those systems isn't used under light load. E.G: is the high pressure pump only used for the direct injectors?

12 minutes ago, Hangie said:

Hi,

Filter is in a tank and even if not officially serviceable can get contaminated and can be replaced. 

There is also relief vale present to avoid too high preasure. Maybe it is faulty and is leaking which leads to too low preasure. 

Car have dual injectors which mean it can be directly or in-directly injected. As you got issues with both injectors types I would start with a pump in tank and filter.

 

 

Thanks for the input Hangie!

I'll have a look at the filter.

The relief valve hasn't been triggered (it's OFF in the freeze frame data), but is there a way of testing it? Do you know where it is physically located?

Something I'm not sure of is how the car would be expected to react if either of the fuel pumps was inoperable - could it run (in the limited way I'm seeing) on one of the pumps alone?