confirmation of vis motor flap info , please.

chris75 · 22nd May 2009, 11:21

Can someone please confirm the "at-rest, ignition off " position for the vis balance valve flap ? Having just removed mine to check for oil problems , I see that the valve flap is at 45 deg , or half open . I think I recall a previous post which stated this should be fully open ? I believe my motor is working ok , and an older "repaired" one i have also sets itself to half-open . Is this as it should be ?

workaholic_ro · 22nd May 2009, 12:10

Both are open at rest either the ignition on or off. The best recommendation I can make is to fit them in an intermediate position and when turning the ignition on the ECU will park them in the resting position. You will hear them buzzing...if working.

Edit: another way to test them if don't have somebody to assist you (and with the risk of collecting some error codes), is to turn the ignition on and after that to connect them one by one.

SD1too · 24th May 2009, 08:48

Quote:

Originally Posted by chris75

Can someone please confirm the "at-rest, ignition off " position for the vis balance valve flap ? Having just removed mine to check for oil problems , I see that the valve flap is at 45 deg , or half open...

Chris,

Yep, mine was open at 45 degrees when I removed it recently. One of the microswitches was high resistance (0.5 - 0.7 ohms) causing the motor to turn with zero torque in one direction. A new switch (87p) fixed that.

You can pull the balance flap out of the chamber quite easily by hand. Mine was very stiff when reaching the closed position so, with fine abrasive paper, I 'eased' it. Engine is running fine, and currently undergoing performance tests.

Quote:

Originally Posted by workaholic_ro

Both are open at rest either the ignition on or off.

Are you sure Fidel? Have you verified this by measuring voltages to the VIS actuators? Since the 'power' valves remain closed unless the engine is running at high rpm, what would be the point of designing the ECU to open them when the ignition is 'off'? It would only have to close them again as soon as the engine starts.

Isn't it more likely that both valves remain closed until the engine rpm reaches the threshold to open first the balance valve then, as engine speed rises further, the power valve?

Simon.

stocktake · 24th May 2009, 11:28

A perfect balance valve sits at around 90 deg open. it closes on operation. Stiff butterfly valves can cause less of an angle, as can microswitches that are not sat "just right".

If the VIS motor is working then as said look at how stiff the flap is and shave accordingly. If the flap gets too stiff it will burn the motor or tracks out.
HTH

workaholic_ro · 25th May 2009, 06:17

Quote:

Originally Posted by SD1too

Chris,

Are you sure Fidel? Have you verified this by measuring voltages to the VIS actuators? Since the 'power' valves remain closed unless the engine is running at high rpm, what would be the point of designing the ECU to open them when the ignition is 'off'? It would only have to close them again as soon as the engine starts.

Isn't it more likely that both valves remain closed until the engine rpm reaches the threshold to open first the balance valve then, as engine speed rises further, the power valve?

Simon.

Yes, I'm very sure. I've studied them to the smallest detail and also their working policy and electric diagram, weak parts, how and why they fail.
They don't remain close, they remain always open unless the throttle is "telling" them to close. You may start the car and go up to the top speed without a single VIS valve position change if accelerating slowly, or you can have up to ten position changes for each one on hard acceleration. I hope it's clear now.
Here:

chris75 · 25th May 2009, 14:42

Quote:

Originally Posted by SD1too

Chris,
You can pull the balance flap out of the chamber quite easily by hand. Mine was very stiff when reaching the closed position so, with fine abrasive paper, I 'eased' it. Engine is running fine, and currently undergoing performance tests.
Simon.

Interesting, this one. I did this over a year ago as it was also binding badly , and freed it off completely . During my recent tinkering I found it was again binding badly towards the closed position ! I have again freed it off by shaving with a pen-knife . Does oil cause the plastic to swell ? Re the at rest position, the motor can be seen to move the spindle into parking position when ign is turned on (connected but not fitted into the manifold ) and seem to move strongly and quickly , but still not 90 deg open ?? Everything seems fine on the road so I guess I'll leave it at that.
Thanks all for your input.

stocktake · 25th May 2009, 15:25

Quote:

Originally Posted by chris75

Interesting, this one. I did this over a year ago as it was also binding badly , and freed it off completely . During my recent tinkering I found it was again binding badly towards the closed position ! I have again freed it off by shaving with a pen-knife . Does oil cause the plastic to swell ? Re the at rest position, the motor can be seen to move the spindle into parking position when ign is turned on (connected but not fitted into the manifold ) and seem to move strongly and quickly , but still not 90 deg open ?? Everything seems fine on the road so I guess I'll leave it at that.
Thanks all for your input.

In the real world what you have is probably typical. I assume as long as the valve is open sufficiently to allow air to pass without any serious restriction you will have no problems. I would also suspect the closing operation is more imperative.

SD1too · 27th May 2009, 19:24

Thanks very much Fidel. How did you obtain the data for throttle angle vs. engine rpm? Very impressive and most informative. The more I learn about it, the more I realise that it's quite a complex system!

Chris: I agree. Even when working perfectly and detached from the flap, my balance actuator don't quite drive the mechanism through 90 degrees. It seems that as soon as the leading edge of the cam on the gear wheel touches the microswitch, it stops instantly, slightly short of the full deflection. However, as you say, this doesn't seem to be significant in real-life driving conditions. In fact, it's no exaggeration to say that the performance of my engine has been transformed since I repaired my balance actuator and "eased" the flap. The engine is much more free-revving, the power delivery is beautifully linear, kickdown is smoother, and my "hunting idle" problem has disappeared! And all it cost me was £1 for a new microswitch. I just want to drive the car all day long now!

Simon.

workaholic_ro · 28th May 2009, 10:27

Quote:

Originally Posted by SD1too

Thanks very much Fidel. How did you obtain the data for throttle angle vs. engine rpm? Very impressive and most informative. The more I learn about it, the more I realise that it's quite a complex system!

I've been searching for all related articles since the day I found that this system is causing a lot of headaches. The graph posted here is from xpowerforums, not sure about the original source and I don't know if it's official; but, according to my own tests and experience I can confirm that this is how the system works.

800victor · 28th May 2009, 22:24

I think the system working in this way

22nd May 2009, 11:21	#1
chris75 same car since 2005 2001 Rover 75 2.0 v6 Connoisseur Saloon Join Date: Nov 2006 Location: Ellesmere Port , Cheshire Posts: 3,818 Thanks: 379 Thanked 549 Times in 466 Posts	confirmation of vis motor flap info , please. Can someone please confirm the "at-rest, ignition off " position for the vis balance valve flap ? Having just removed mine to check for oil problems , I see that the valve flap is at 45 deg , or half open . I think I recall a previous post which stated this should be fully open ? I believe my motor is working ok , and an older "repaired" one i have also sets itself to half-open . Is this as it should be ? __________________ Who said it was simples ?

22nd May 2009, 12:10	#2
workaholic_ro Gets stuck in Rover 75 Saloon Join Date: Mar 2007 Location: Cluj Posts: 551 Thanks: 0 Thanked 3 Times in 3 Posts	Both are open at rest either the ignition on or off. The best recommendation I can make is to fit them in an intermediate position and when turning the ignition on the ECU will park them in the resting position. You will hear them buzzing...if working. Edit: another way to test them if don't have somebody to assist you (and with the risk of collecting some error codes), is to turn the ignition on and after that to connect them one by one. __________________ Renee Descartes walks into a bar, the bartender says 'sir can I get you a martini 'Descartes says 'I don't think...' and he disappears Cheers, Fidel Last edited by workaholic_ro; 22nd May 2009 at 12:16..

24th May 2009, 11:28	#4
stocktake Vis Whiz Rover 75 2.5 auto Saloon Join Date: Jun 2007 Location: LEEDS Posts: 20,594 Thanks: 2,057 Thanked 3,056 Times in 1,621 Posts	A perfect balance valve sits at around 90 deg open. it closes on operation. Stiff butterfly valves can cause less of an angle, as can microswitches that are not sat "just right". If the VIS motor is working then as said look at how stiff the flap is and shave accordingly. If the flap gets too stiff it will burn the motor or tracks out. HTH __________________ Dave... Lost a few stones and a Gall Bladder and part of a bile duct and all of my dignity in the suppository incident

27th May 2009, 19:24	#8
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,485 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Thanks very much Fidel. How did you obtain the data for throttle angle vs. engine rpm? Very impressive and most informative. The more I learn about it, the more I realise that it's quite a complex system! Chris: I agree. Even when working perfectly and detached from the flap, my balance actuator don't quite drive the mechanism through 90 degrees. It seems that as soon as the leading edge of the cam on the gear wheel touches the microswitch, it stops instantly, slightly short of the full deflection. However, as you say, this doesn't seem to be significant in real-life driving conditions. In fact, it's no exaggeration to say that the performance of my engine has been transformed since I repaired my balance actuator and "eased" the flap. The engine is much more free-revving, the power delivery is beautifully linear, kickdown is smoother, and my "hunting idle" problem has disappeared! And all it cost me was £1 for a new microswitch. I just want to drive the car all day long now! Simon. __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.