Power VIS issue
 

Hello,
I read many threads here about the VIS motors so i've tried fixing mine. I managed to get the balance one working but with the power one i encountered the following problem:
Fixed the tiny dc moor inside, fixed the electrical connection and checked the microswitches for resistence. All ok so i refitted the power VIS.
Before inserting the electrical connector i switched the ignition to on position so i could see if the vis is working. When i connected the cable the vis started spinning, clicked both microswitches but never stoped. It just keeps spinning. Another info that i can give is that when i run a diagnostic tool, at idle , the balance vis is beeing displayed as inacvtive but when i rev the engine it gets activated( as it should). The power VIS is allways displayed as active no mather the rpm.
Can you tell me what signals the vis to open or close?
Any help is apreciated!
PS: I'm romanian, please be kind with my english! :D

HI Cosmin.
I am sure our resident Vis motor expert ( Stocktake ) will be along shorty he will no doubt give you all the information you need, if not you could always drop him a PM he will not bite.

If he did it would a love one :D

I'll wait for his answer. Thank you!

I think you may be mixing up the power and balance Vis motors.
It is the balance one that has the ability to continuously go round and round if it is not connected to the balance flap.
The power Vis (the one on the top) could simply over rotate and stop it will not go round and round.
If your balance Vis (the one on the side ) is going round and round you need to take the top off the Vis motor case and re position the cam on the final drive wheel so it is in between the two micro-switches. then when you reassemble it do not attempt to operate the Vis motor unless it is connected to the balance flap as this acts as a stop to stop the motor rotating continuously.
hope that helps.

Now, Steve, where do you want this love bite :D :)

This is what i got from reading previous threads.
Balance VIS is the one that controls long/short intake channel.
Power VIS is the one that controls the six butterfly valves and the one that creates the rattle(witch i have).
Balance vis works. I performed a test with my diagnose and i can hear the tini dc motor and even the flap snaping closed.
Power VIS, the one that controls the six butterfly valves, spins continuouslly so please help me with that.

When you say the power Vis spins continuously do you mean the final drive peg can actually be seen going round and round? Or, can you just hear the motor running? If it is the latter then the gearing inside has stripped from the final drive or the "bell end" of the motor has lost its grip on the spindle.

Just for clarity, this is the power Vis

https://www.ebay.co.uk/itm/Land-Rove...MAAMXQjwVQ-hWa

Yes that is the VIS that i am refering to. With ignition on and the VIS in my hand i connect the cable and the wheel starys spinning without stopping. Maybe that the microswitches aren't pushed enough by the cam on the rotating gear? I cand hear both of them clicking though.

OK Cosmin,
That is good information, your problem will almost certainly be in one of of the microswitches, either it is not positioned correct on the cam or the end of the switch has broken off which is hard to see but very common.
Simple to fix by changing the switch. Have a good look at both the switches and if you cannot see a problem just put your meter on then to check for continuity. then check the continuity is broken when you press in the switch. If it is the switch not opening then some of them can be taken apart and cleaned but some are none openable.

Edit: Switches ( cut middle leg off, not reqd.)
https://uk.rs-online.com/web/p/micro...d%22%3Atrue%7D

Removed the power VIS and rechecked everything. Zero rezistance on both microswitches, checked and resoldered some connections but the problem is stilk there. When i plug the cable in the gear wont stop spinning. I tried to push the switches by hand.. the same they don't do anything. So now i'm thinking about replaceing the small siemens relay inside.. For now i have refited the vis back without the actuator motor and blocked it into open position as i saw in some other threads. The engine runs ok in this configuration and of the replacement relay wont fix the issue then thats how it will remain. On another thread i've read that very few kv6es on road have both vis motors working.

OK, when you push the switches in by hand you should go from zero resistance to infinite resistance on your meter. pressing the switches in should stop the motor, if not the switch is faulty. Again, have you checked the end of the switches, they break off very easily and it is easy to miss. I very much doubt it will be the relay.
Look at the attached diagram, (thanks to workaholic) you can see that the switch has to make to send the power to the motor. One of your switches is faulty

https://www.the75andztclub.co.uk/for...9dbfb477f4.jpg

While it is true that a lot of KV6s will have non-functioning VIS motors, it is by no means desirable. I offer a free checking service and generally find most owners will have one defective VIS (usually the balance), if unlucky sometimes both. However, functioning VIS motors make a lot of improvement to the engine, one defective motor is often not noticed, but owners who have replaced both motors generally report a noticeable improvement in performance, this is especially true of the weaker 2.0 engine.
Stocktake who has kindly answered your questions also provides a VIS renovation service. His renovated units incorporate many improvements over the original design and will probably outlive your car.

Regards

When VIS motors are operated in situ the load of the flap or butterflies reduces the speed of the motor and prevents overrun when the micro switch switches the motor off at the end of travel. If you operate the VIS motors off the car they run so fast that they reach the end of travel and operate the micro switch but they are spinning so fast the cam rotates a bit more than it should and switches the end of travel micro switch back on and the motor carries on spinning. Many years ago I repaired one and operated it off the car and the above happened. I remember having to strip the unit down again to rectify it but I can't remember what I did to rectify it. If I have to run them off the car now I apply some load to the output peg/square hole with my hand to prevent overrun.

Mostly correct but as the power butterflies loosen with age or indeed wear there is a good chance a standard Power Vis motor can over run and the cam then hits both switches at the same time. This renders the Vis useless until stripped and reset. All of my Power Vis motors now incorporate a limiter pin that 100% stops this from happening. ;)

Hello.
I am sorry for my late reply but i'm working on this car on my spare time.( She had ALL the commun issues )
Thank you for the provided diagram. I checked again the microswitches and they work perfectly yet the motor spins without stopping. I think i will try to check the electrical conector but for now, i am satisfied with the way the engine idles and runs. It took time to make it idle propperly.
Electrically, now i'm left with a high speed radiator fan error code. When i test the fan with my diagnose i can hear the relay clicking but the fan doesn' start.
*The fan starts when the AC is on and requires the fan for cooling.
I read that i have to remove the front bumper to see whats causing the problem there. Will do that.
Someone wanted to scrap the car because he took it to many mechanics but still the car wasn't fixed. Here in Romania vag group cars are very popular but comun issues with vag group cars don't apply to rover cars so i understood why the car wasn' fixed. So i buyed the car (very cheap) from the guy and started working on it and then started to like it. Now it only has the issue with the cooling fan witch i will fix next week.
Other than that everything works.
Thank you.

True. My car is a 2.0 and had both vis motors broken. I managed to fix the balance one and the improvement was substantial. I don't intend to leave it like this but i don't want to get stucked on this issue. Since the engine works fine, i can fix the rest of the problems, register the car , and then check the power vis again.

Hi Cosmin,
Thank you for coming back to us and I am sorry you cannot find the fault. Providing the wiring on the car is correct then it can only be the micro switch.
You are correct not to let it stop you getting your car roadworthy, until you can find time to fix this simply leave the Vis motor unplugged.

I have only ever come across this once and that was when the plug that should go to the lamda sensor was inadvertently plugged into the Vis as they were the same plug fitting!!

When you are ready to look again at the Vis motor send me a message and I can tell you the colour of the wires that go to the Vis and what voltage they carry. That said a continuity test of the switches Open and closed) is a must to move forward.

Good luck with the rest of the car.

Can you please tell me where are these plugs located?

The plugs go to the sensors in the exhaust one of them is quite close to the vis motors at the back of the engine.
Just to make sure you have the correct plugs fitted to the Vis motors you should have the following colours on the plug.

Power:
1. Orange/Yellow
2. Black
3. Blue/Yellow
4. Blue/Pink

Balance:
1.Grey/Black
2. Blue/Orange
3. Black
4. Blue/Yellow

SO... the VIS plug and the lambda sensor plug were swapped.(I had a o2 sensor error code but I thought this would go away after i drive it around since the car hasn't moved since 2014)
i feel so dumb now :)) but i would never thought that the o2 sensor could have the same plug as any other plug on the engine.
NOW.. the power vis does this: With the cam of the gear between the microswitches if I plug in the cable the gear rotates and when it hits the microswitch it stops. But when I test it with the diagnose it doesen't rotate towards the other microswitch.. the balance motor does.

Cosmin that's great news :D
Glad I could help.
If your sure the switches are OK then sounds like a dry solder joint or the relay is fried on the Vis
Part No: V23079A1003B301

Good luck with the rest of the car and most of all thanks for coming back to let us know. :bowdown:

Edit, just had a thought, if when you plugged the Vis motor in it is possible the gear over rotates and the cam actually hits both microswitches and then it locks up and will not move as both switches are open. Usually the resistance of the brown arm in the manifold stops this over run. have a quick look ;)

I tested it without the cover mounted on the vis so i saw that it rotates towards one of the switches but not towards the other. I will check the relay.
Thank you

Update time :)
So regarding the topic of this thread, it was the relay on the board. After i changed the relay the vis worked but then after a few tests the dc motor failed.
I left that as it was and carried on with other problems on the car( there wore some) . If you want i can list all the problems that the car had but, at the moment, the only thing not working is the power vis.
The good news is that, since yesterday, the car is registered and road legal.
I’ve read about some upgraded vis motors which i intend to buy because there is a drop of power at low rpm and a revhang that is causing engine brake at some points. I’m suspecting that the power vis might cause these problems since the cars pulls really well above 3000-3200 rpm.
So could you please send me a link from where i could buy the updated power and balance vis actuators?
Thanks!

Stocktake who has answered your questions also provides the upgraded VIS motors, just click on his name (Stocktake) on the left to send him a PM.

I recently noticed the same lack of power due to a faulty power VIS and I have replaced many for local members. Usually my experience has been that a faulty power VIS doesn't make that much of a difference but on a recent car the power VIS had stopped in the open position meaning that the owner (my daughter) wasn't getting the benefit of the low down torque at 2700 rpm. It was almost like the difference between a 2.0 and a 2.5, once changed it was immediately noticeable.

Regards

Mine is the smaller 2.0 liter so the impact is greater. I left the intake butterflies on open and at low rpm the engine feels like a 75 hp clio so i allways have to downshift for more power. i will pm stocktake.
Thanks!

If most of your driving is around town try closing the butterflies (and balance if that's open) by moving the brown arm all the way to your passenger side (closed) the car should then be at max torque at 2700 rpm (2.0 & 2.5). In the medium range the power vis should still be closed but the balance open, now the peak torque is at 4000 rpm for the 2 ltr (3750 rpm 2.5).

The power vis only really comes into action after 4000 rpm - 6500 rpm (2.0)

Regards

Thanks for info. The balance vis works so i will try to move the butterflies.

Hello Cosmin,

I'm sorry to say that leaving any of the valves in one position won't be a satisfactory solution. Providing that the balance flap moves freely (they are prone to sticking in the mid position) and the butterfly linkage isn't broken then what you need is a working VIS actuator to restore proper performance to your engine throughout the rev range. As said previously, Stocktake can supply you with the improved version you've heard about.

If you're feeling adventurous, remove the plastic manifold chamber entirely and clean out the carbon blocking the breather pinhole in the RH camshaft cover (the LH can be done much more easily). This piece of maintenance will also enhance the response of your engine.

Simon :}

Thank you for your answer Simon.
I can test if the vis motors are working with my delphi tester. I can hear the balance vis working and the flap shuting closed. The power vis does not work anymore.
The butterfly linkage is in good shape. I,ve checked them when i replaced the timing belts, water pump and tensioner roller. Thats when i cleaned the inside of the inlet manifold. I’ m not sure i understand what you mean by the pinhole of the camshaft cover. Could you please tell me where is that pinhole?
Thanks.

The actuator needs renewing then! :D
I certainly can! :} Each camshaft cover has two breather tube connections fitted internally with wire mesh filters. If you remove these filters you'll see that behind one of them, the suction connection to the throttle body, is a pinhole restriction. This is what needs clearing.

Simon

Will do, thank you

Ok, just to warn you Cosmin that removing the plastic manifold chamber to access the RH cam cover is quite a job. The worst part is two hidden screws at the back. A Haynes manual will be helpful.

Simon

This thread can be marked as SOLVED :D:D:D

Dave sent me a part to fix the power VIS. Many thanks to Dave for his help.
Now both VIS motors are working!

Now for my feedback regarding the vis motors:
With the tester connected to the car, I have noticed that the VIS motors go active, depending on how much the throttle pedal is pressed and not necessarily depending on the rpm of the engine. I could press the throttle jus a little and go up to about 5000 rpm and the tester would not indicate that the vis motors are "active" or I could fully press the throttle and the Vis motors will instantly go active and open the flap and butterflies , from 1000 rpm all the way to the end of the rev range. This makes sense because now I have better low end torque and the car pulls better at lower rpm.
It is not correct to say that the engine has more power with working VIS motors than it had without them but it is correct to say that the engine delivers the power that it had at 4000 rpm, without working VIS, sooner at around 3000 rpm, with working VIS and now there is plenty of torque at 2000 rpm. I don't have to downshift to overtake anymore.

Conclusion of this thread : WORKING VIS MOTORS ARE A MUST!
Best regards and many thanks for your help

Correct! :D

I can endorse this having made the same discovery some years ago (with the assistance of T4). It's the rate of change of throttle opening to which the VIS system reacts; in simpler language that's how quickly the accelerator pedal is pressed.

Thanks for posting this Cosmin.

Simon

Sorry need a bit of help here as the description I have in Rover’s Technical Brochure doesn’t match that which is given here.

“about 5000 rpm and the tester would not indicate that the vis motors are active” - at 5000 rpm both VIS motors should be active according to Rover.

“I could fully press the throttle and the vis motors will instantly go active” - if I fully press my throttle I’d expect the same as the engine is now well over 6500 rpm.

When the helpful Rover 54 (Ed) connected his T4 in London to my car in Sweden he tried to test the VIS motors. I followed his instructions pressing the throttle to take the engine over what he considered the trigger rpm - the results were “inconclusive”. Toaf however is able to active each vis motor even without the engine running.

Nowhere in the Brochure (mines actually called a Tekniskt kompendium which is a far better name) does it mention the mechanical throttle. I would better understand if there’s a direct link between the throttle position sensor and the VIS motors. Is there one?

Dave, where are you?

Thanks for coming back to us with the outcome of this.

Just to clarify, Cosmin161 has stripped his Vis motor down and correctly diagnosed that the motor itself had failed, After a few Pm's all I did was send him a replacement motor FOC to his home in Romania.

On the subject of the motors operating it is my understanding that the vis motors remain unactivated when less than 31% of throttle is used. Above this then they work their magic working together. There are graphs somewhere on here to support this.

-not the case because i only touched the throttle as the revs slowly built up to 5000 rpm. if you don't demand power from the engine by presing hard on the throttle pedal, the VIS system will not activate and the engine will slowly and silently rev up without opening the balance flap or bfly valves.

-yes, but they activate right from idle rpm not from 3500 rpm (and you can hear some sweet intake noises ).

-i think that the tests were inconclusive because of the 31% throttle input that Dave stated. Sometimes you pressed it above 31% sometimes bellow while you where expecting the VIS system to be triggered by the revs.

If interested, i can upload a vid to YT so you can see what i mean.

The truth about the VIS system
 

I can help here because the discovery I mentioned in my last post was using Ed's (retired member Rover54) T4 and a club member's ZT-T. With the car stationary and the engine speed slowly increased to around 5,000 rpm, the power valve actuator did not move. Repeating the test but by rapidly moving the accelerator pedal resulted in the actuator operating. This was all observed by the three of us on Ed's T4. Therefore as Cosmin161 correctly points out, the assumption that the VIS system works by engine speed alone is incorrect.
Hi Mike,

You say that the document you have is called a Tekniskt kompendium. I'd be interested to know what this actually says. Is it possible to post the actual quote, translated by you of course! :D
Also, I suspect that there are documents in circulation which resemble MGR publications in appearance but are not genuine (I believe that I have one!). Are you certain that your Tekniskt kompendium isn't one of these?
Yes there is a link. The throttle position sensor is connected to the ECM which also drives the VIS actuators. Software will be involved of course and it is that which we are learning about here.
Hi Dave,

I believe you're referring to the bar graphs which are not official MG Rover but the interpretation of an unknown person. They don't take account of the speed at which the throttle was opened.

When you kindly lent me your balance actuator & flap test rig I noted that the flap remains open (its default position) unless the throttle angle is changed rapidly. This is consistent with my earlier observations of the power valve described above and with Cosmin161's findings.

The VIS system therefore will operate only if the throttle movement is fast, in other words when maximum torque is required rather than leisurely cruising.

Simon

Thinking about it at the time we communicated about the operation, I believe I posted a short Vid which actually showed the balance flap open at rest and with a short sharp tap on the accelerator snapped shut, so this supports this.

OK thanks for the replies, not much clearer in my head though.

In the genuine Rover Brochure (197 pages) Rover Service School (translated) there is no mention of percentages of throttle action only rpm. Duncan on the enthusiasts site had an English language version of the same publication, quite rare.
But there is no mention of slow or rapid pedal (TPS sensor) activation although I accept its possible to fool the system. What I really have a problem accepting is the fact that it’s possible to slowly take the engine up to 5000 rpm without any VIS activation, but if several people have observed this then perhaps it’s time to re-evaluate my understanding.

OK bit of translating time. There is a diagram too which shows the position of the various flaps, balance flap, etc.

Then it goes on to say:

The inlet manifold has a variable length in 3 steps and this applies to both engine sizes. It works as follows:

1. At low rpm the balance valve and valve controlling the effect duct is closed. This causes the engine to breath as two 3 cylinder engines each with its own separate mixing chamber and long power ducts, which means that the engine reaches peak torque at 2700 rpm.
2. To improve torque in the medium range the balance valve is opened while the power valve remains closed. Max torque is now reached at 3750 rpm (2.5 ltr) and 4000 rpm (2.0 ltr).
3. At higher engine speeds both the balance and power valve are open. Achieving now a range of torque upwards from 4000 rpm to a maximum of 6250 rpm (2.5) and 6500 rpm (2.0).

The construction of the inlet manifold also gives increased fuel economy at part load. Through the entire emissions cycle the manifold works at part load according to point 3.

Pumping loses (the action of the pistons to suck in air and press out exhaust gases) at sub 4000 rpm has by means of this construction been drastically reduced. This results in improved fuel economy.

OK, perhaps the translation needs some polishing but will have to do. Next question would be, if by not allowing the system to active as designed are you losing out on fuel economy as well as torque?

Keep well

On all the failed motors I have replaced/repaired it has always depended on what position the valves have failed in as to what the owner experiences, either better/smoother delivery of power, or better mpg, or a little of both. Most common by far is the feeling of no power lowdown in the rev range and this is always the case if the balance vis fails in the closed position.

Thanks Dave, you may recall this post and like you say, it depends on what position if fails but in this case t'was the power VIS

https://www.the75andztclub.co.uk/for...42#post2843642

Keep well

Thank you for this Mike. It's almost the same as RAVE including, according to our tests and observations, giving the state of the flaps incorrectly in all three paragraphs! :getmecoat:

Really the official version of how the inlet tracts work is not very helpful at all. I think we all share your confusion Mike! :cool:

Simon