VIS Motor Question

outbound · 4th September 2007, 20:18

Hi Everyone,
Please excuse my ignorance and I do not
mean to sound like a mechanical Hypochondriac, but could someone
tell me what the VIS Motors are and what they do. Also how would you know if they were starting to fail? Is there also anyway to look after them to
prevent them failing.
Thank you in advance,
Jeff

Simon · 4th September 2007, 20:24

VIS motors are the actual motors on the KV6 engine that open and close the butterfly valves in the inlet manifold.

The two of them (power valve and balance valve) open and close the inlet tract length to adjust the power/torque of the engine through it's rev range. This helps smooth out the power/torque curves.

When operating normally, the balance valve opens around 3100rpm and the power valve around 4500rpm (i think?). You will notice a definite "kick" in performance if you keep your foot down and the rev counter passes these points.

Serious problems with either valve can usually be heard as a loud and repetitive ticking noise (that can be heard easily) from the motors. Other indications of malfunction can be by - for example - not experiencing the "kicks" as described or poor performance. You engine management will log faults that can be read by Testbook if such failures/malfunctions are happening from the VIS motors.

Simon · 4th September 2007, 20:25

This post in this thread may also be of use to you regarding diagnosing VIS motor problems: http://www.the75andztclub.co.uk/foru...7&postcount=28

outbound · 4th September 2007, 20:35

Thanks Simon,
There reason I asked, was after yet another wax tonight, I had the engine running with the bonnet open and gave it a rev from
the engine compartment. There was a tappet type noise from the top of the engine but not at higher revs. When I have given the car the odd kick down
in there past few weeks all power is there and it shoots of like a rocket.
So I was wondering if it could be the VIS motors.
Thanks again,
Jeff

Simon · 4th September 2007, 20:37

Could it be something described by a few of us in this thread here http://www.the75andztclub.co.uk/foru...ead.php?t=1934 ??

EDIT: Thread contains a sound clip of a failed VIS motor so you can eliminate that from your investigations

Lates · 4th September 2007, 20:52

On a side note, I tested a ZT190 last week with no fault codes and a definate power valve failure. Even unplugged no code was logged ???
The vis tester I have works wonders in this example to prove either way if the motor works or not.

Mike · 4th September 2007, 21:01

Hi mate,

Latest vis motor instal still operating well

Leighton Buzzard bypass tonight, came off the roundabout and planted it - all I can say

outbound · 4th September 2007, 21:04

Hi Lates,
Still waiting on the re mortgage so hopefully will be in touch soon
Perhaps you would have a look at when I see you. Maybe its not a VIS
motor has the car appears to have all it's power.
Looking forward too meeting you.
Jeff

Lates · 4th September 2007, 21:05

Mr Mike as you know R40 was the second recipient of Version 1.0 power valve mod and please to hear the durability testing is going well

Lates · 4th September 2007, 21:07

No problem Jeff, you are more than welcome to watch the 8th wonders of the world perform

4th September 2007, 20:18	#1
outbound Regular poster Rover 75 saloon 2.5 conn Join Date: Aug 2007 Location: shepperton Posts: 57 Thanks: 0 Thanked 0 Times in 0 Posts	VIS Motor Question Hi Everyone, Please excuse my ignorance and I do not mean to sound like a mechanical Hypochondriac, but could someone tell me what the VIS Motors are and what they do. Also how would you know if they were starting to fail? Is there also anyway to look after them to prevent them failing. Thank you in advance, Jeff

4th September 2007, 20:24	#2
Simon Banned - Join Date: Nov 2006 Location: - Posts: 10,318 Thanks: 0 Thanked 4 Times in 3 Posts	VIS motors are the actual motors on the KV6 engine that open and close the butterfly valves in the inlet manifold. The two of them (power valve and balance valve) open and close the inlet tract length to adjust the power/torque of the engine through it's rev range. This helps smooth out the power/torque curves. When operating normally, the balance valve opens around 3100rpm and the power valve around 4500rpm (i think?). You will notice a definite "kick" in performance if you keep your foot down and the rev counter passes these points. Serious problems with either valve can usually be heard as a loud and repetitive ticking noise (that can be heard easily) from the motors. Other indications of malfunction can be by - for example - not experiencing the "kicks" as described or poor performance. You engine management will log faults that can be read by Testbook if such failures/malfunctions are happening from the VIS motors. Last edited by Simon; 4th September 2007 at 20:27..

4th September 2007, 21:01	#7
Mike This is my second home Rover 75 V8 Join Date: Oct 2006 Posts: 3,448 Thanks: 0 Thanked 206 Times in 32 Posts	Hi mate, Latest vis motor instal still operating well Leighton Buzzard bypass tonight, came off the roundabout and planted it - all I can say __________________ Mike [SIGPIC][/SIGPIC]

4th September 2007, 20:25	#3
Simon Banned - Join Date: Nov 2006 Location: - Posts: 10,318 Thanks: 0 Thanked 4 Times in 3 Posts	This post in this thread may also be of use to you regarding diagnosing VIS motor problems: http://www.the75andztclub.co.uk/foru...7&postcount=28

4th September 2007, 20:35	#4
outbound Regular poster Rover 75 saloon 2.5 conn Join Date: Aug 2007 Location: shepperton Posts: 57 Thanks: 0 Thanked 0 Times in 0 Posts	Thanks Simon, There reason I asked, was after yet another wax tonight, I had the engine running with the bonnet open and gave it a rev from the engine compartment. There was a tappet type noise from the top of the engine but not at higher revs. When I have given the car the odd kick down in there past few weeks all power is there and it shoots of like a rocket. So I was wondering if it could be the VIS motors. Thanks again, Jeff

4th September 2007, 20:37	#5
Simon Banned - Join Date: Nov 2006 Location: - Posts: 10,318 Thanks: 0 Thanked 4 Times in 3 Posts	Could it be something described by a few of us in this thread here http://www.the75andztclub.co.uk/foru...ead.php?t=1934 ?? EDIT: Thread contains a sound clip of a failed VIS motor so you can eliminate that from your investigations

4th September 2007, 20:52	#6
Lates This is my second home Jaguar XE Join Date: Nov 2006 Location: Coventry Posts: 4,321 Thanks: 56 Thanked 59 Times in 55 Posts	On a side note, I tested a ZT190 last week with no fault codes and a definate power valve failure. Even unplugged no code was logged ??? The vis tester I have works wonders in this example to prove either way if the motor works or not.

4th September 2007, 21:04	#8
outbound Regular poster Rover 75 saloon 2.5 conn Join Date: Aug 2007 Location: shepperton Posts: 57 Thanks: 0 Thanked 0 Times in 0 Posts	Hi Lates, Still waiting on the re mortgage so hopefully will be in touch soon Perhaps you would have a look at when I see you. Maybe its not a VIS motor has the car appears to have all it's power. Looking forward too meeting you. Jeff

4th September 2007, 21:05	#9
Lates This is my second home Jaguar XE Join Date: Nov 2006 Location: Coventry Posts: 4,321 Thanks: 56 Thanked 59 Times in 55 Posts	Mr Mike as you know R40 was the second recipient of Version 1.0 power valve mod and please to hear the durability testing is going well

4th September 2007, 21:07	#10
Lates This is my second home Jaguar XE Join Date: Nov 2006 Location: Coventry Posts: 4,321 Thanks: 56 Thanked 59 Times in 55 Posts	No problem Jeff, you are more than welcome to watch the 8th wonders of the world perform