Testing VIS causes rattle

[SteveThackery]

Originally Posted by SD1too

Steve,

Unfortunately your link cannot be viewed without creating an account. However, we are aware of RAVE's description of the VIS system and I can confirm that what Dave (Stocktake) has said is correct as you are no doubt about to find out for yourself!

Simon

Simon, is there a way I can post a picture directly?

And yes, I'm sure Dave is right. I just don't want to take the mickey out of people who have read the RAVE and assumed it's authoritative. After all, it certainly should be!

[SteveThackery]

Dave's discovery that the RAVE description is completely wrong is really interesting to me and it makes me wonder how RAVE made such cokc--up.

My theory on why my power valves rattle when actuated is also nonsense! They are silent when open, and rattle when closed, and I can't for the life of me work that one out.

One thing many people (including me) seem to misunderstand: the balance and power valves do their thing at LOW rpms, not high rpms. According to the diagram linked above, from 4350rpm upwards it's all over for the valves, and they are in the same mode as when the engine is idling. The valves only do their stuff when the throttle is more than 31.4 degrees open, and the rpm is less than 4350.

Dave - what is the provenance for the diagram you posted? I'd be interested to find out where it came from because it looks like the source will be more reliable than RAVE.

[stocktake]

Originally Posted by SteveThackery

Now this is most interesting. To be fair to these "experts", they are only quoting the Technical Brochure, a screenshot of which is attached.

https://www.dropbox.com/scl/fi/k3oxc...sung-Notes.jpg

That says the exact opposite, which is very interesting and confusing!

Not signed up to dropbox, sorry
Oh, I am well aware that the cut and paste army do simply that and no doubt we have all done that to offer information up in good faith but when they claim it as their own research it's a different matter Steve

I am happy to quote rfom Rave or the tech manual but never claim it as my own research.

And again to be fair it's not the only anomaly in the manual, take for instance the wiring diagram for the cooling fan that states the purple wire from the relay box is 12v live when in fact it is a negative


As for the source of the diagram, it was first posted on here many moons ago by previous technical bods so again Is it correct? I don't think anyone has gone that far into it ....

[SteveThackery]

Thanks for your reply, Dave.

I think if I were a car manufacturer I'd be tempted to keep an eye on forums like these, specifically to detect and prevent the spread of misinformation. In the case of Rover, of course, there's no-one left to do that, but I'm active on a forum for Royal Enfield motorcycles, and that company is very much alive and going from strength to strength. There's a lot of uninformed drivel spoken on the forum, and I always think it would be in RE's best interest to put right the numerous misconceptions about their bikes.

One staff member working part time would probably be enough to keep most of the content on the straight and narrow.

I didn’t realise people were claiming ownership of the info they'd discovered in RAVE. That's a heck of a cheat.

One day I fancy kitting out my car with the tell-tale LEDs and trying to get a clearer picture of exactly what VIS motor does what under various conditions - see if it confirms the diagram we've inherited from the previous technical bods.

[SD1too]

Originally Posted by SteveThackery

Simon, is there a way I can post a picture directly?

Yes, in the new message pane click on the rectangular mountains icon to "insert image" directly from your computer.
Correction: Click on the paper clip icon. Sorry about that.

Originally Posted by SteveThackery

Dave's discovery that the RAVE description is completely wrong is really interesting to me and it makes me wonder how RAVE made such cokc--up.

This is my own theory Steve, made without any substantive evidence! The advent of the computer has changed the requirements of a good manual writer from technical expertise in the field to the ability to manipulate IT programs.

Originally Posted by SteveThackery

One thing many people (including me) seem to misunderstand: the balance and power valves do their thing at LOW rpms, not high rpms. According to the diagram linked above ...

That block graph is of unknown provenance, is rather crude and misleading.
Really it shouldn't be referred to any more. What we know from practical experience is that the balance flap operates at about 3,000 rpm and increases engine torque, particularly useful for accelerating up inclines. The power valves react to fast and large throttle openings, producing rapid acceleration.
The idea behind the VIS system is to produce a nearly flat torque response across the whole rev. range.

Originally Posted by stocktake

... it's not the only anomaly in the manual, take for instance the wiring diagram for the cooling fan that states the purple wire from the relay box is 12v live when in fact it is a negative

And there are other errors too.

Simon

[SteveThackery]

Originally Posted by SD1too

This is my own theory Steve, made without any substantive evidence! The advent of the computer has changed the requirements of a good manual writer from technical expertise in the field to the ability to manipulate IT programs.

Simon

I have a more generous theory!

I suspect that at the time the Technical Brochure was being written, the R75 was still under development and undergoing fine tuning and the finishing touches. I suspect that the description of the VIS functionality was, indeed, correct at the time of writing - it reflected the original design intent.

Subsequently the engine was tested and tuned on the dynamometer, during which time they found that a different VIS control algorithm produced the best results. So this new algorithm was baked into the ECU, but nobody thought to go back and update the Technical Brochure.

So, that's my take on what might have happened.

[SteveThackery]

Originally Posted by SD1too

Yes, in the new message pane click on the rectangular mountains icon to "insert image" directly from your computer.

That's weird, because when I click on the mountain it says "Please enter the URL of your image". "URL" is the term for any Internet address. The address line is prefilled with "http://", which again implies that it's expecting an Internet address. It won't let me paste a folder and filename for the picture.

So what am I doing wrong?

(I wonder if it's because I'm using an Android tablet.)

[SteveThackery]

Originally Posted by SD1too

That block graph is of unknown provenance, is rather crude and misleading.
Really it shouldn't be referred to any more.

Well that's fine by me. With no provenance it's worthless in my view, but it was Dave who posted it and I didn’t want to disrespect him.

Originally Posted by SD1too

What we know from practical experience is that the balance flap operates at about 3,000 rpm and increases engine torque, particularly useful for accelerating up inclines. The power valves react to fast and large throttle openings, producing rapid acceleration.
The idea behind the VIS system is to produce a nearly flat torque response across the whole rev. range.

When I fitted the new VIS motors I mostly noticed an improvement in the low to mid-range responsiveness to the throttle. When I bought the car it always seemed to need a lot of throttle before it would get moving with any vigour. With the new motors the car seems to respond more readily to the throttle - it feels more "normal".

Of course we don't know what positions the valves were left in when my VIS motors failed.

One day I will hook up the VIS motors to some kind of data logging so I can begin to get a picture of exactly when each of them actuates and releases.

[SD1too]

Originally Posted by SteveThackery

That's weird, because when I click on the mountain it says "Please enter the URL of your image".
So what am I doing wrong?

Nothing Steve, it was my error. It's the paper clip icon that you click on to post an image directly from your computer, sorry!

Hopefully to conclude the discussion about the VIS actuator graph ...

Originally Posted by SteveThackery

With no provenance it's worthless in my view, but it was Dave who posted it and I didn’t want to disrespect him.

Yes, I don't find it very helpful at all, more confusing in fact. Dave has also questioned its accuracy here ...

Originally Posted by stocktake

As for the source of the diagram, it was first posted on here many moons ago by previous technical bods so again Is it correct?

Simon

[SteveThackery]

Originally Posted by SD1too

Nothing Steve, it was my error. It's the paper clip icon that you click on to post an image directly from your computer, sorry!
Simon

This is embarrassing, and, I'm sorry for being thick, but I can't seem to find any paperclip icon. I wonder if it's a setting somewhere that's the trouble. At the top of the message box I have two rows of icons:

AA (crossed out), Fonts, Sizes, text colour, smilies, undo, redo

On the second row:

Bold, italic, underline, justify left, justify centre, justify right, numbered list, bullet list, outdent, indent, insert Internet link, delete Internet link, insert Internet email link, insert Internet picture link, # button, <> button, insert PHP code button.

To the right is a box of smilies; underneath is a box of icons

Whereabouts should the paperclip be, Simon?