VIZ MOtor Issue

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Rich in Vancouver

Rich in Vancouver

Well-Known Member
Posts
395
Location
Near Vancouver Canada
This morning my V6 Hippo started running like it was on 4 or 5 cylinders. (Yesterday, on my commute home it ran like a champ-no issues)
I've had a quick look at it. The codes led me to the VIS motors. Since I got the Hippo I have had a humming/motor noise coming from the engine compartment after shutting it off. Lasts about 20-30 seconds. I assumed that it was a fuel pump, but today after taking off the engine cover I found it was coming from the upper VIS motor. It feels warm to the touch and you can feel a vibration.
I searched old threads and found one by Sheddist that covered re-soldering the microswitch contacts but nothing on the motor running on like that.
I can't see why it would have to run after shutdown and am thinking it may be doing whenever the engine is running.
Does anyone have any experience with this fault? I can order one from the USA so it's about 4 days away but would still like drive the Hippo to work in the meantime.
Before I pull the VIS out and take it apart as per Sheddist, does anyone have a quick fix suggestion?
 
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That was straightforward...I pulled the VIS and took it apart to find the nylon gear is stripped.
Could be one of the limit switches failed and the motor turned till it stripped. I have ordered a new VIS but can anyone suggest which position to put the broken unit back in till it arrives? Should the slide in the manifold be in the outboard or inboard position for the best compromise to run in the meantime?
 
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The VIS motor has probably failed because one of the limit switches hasn't closed at the end of the rack.
From memory. The power values are closed with the rod to the left and open with it to the right.
Closed is best for torque. Open gives better power over 4K Rpm.
 
You are probably right about the limit switch. When you say to the left do you mean towards the wing or the center of the vehicle?
It does sound like the engine will run either way. With the auto gearbox the revs rarely if ever get above 4000RPM.
And....once the damaged VIS is reinstalled temporarily can I just leave it unplugged or would it be better to jam both limit switches in the closed (or open?) position?
I've got the new VIS on order and should have it by Wednesday.
 
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Move the slider to the passenger side of the vehicle. Not towards the centre of the car.
Leave the plug disconnected for the time being;)
 
:D That's why I was going with "Inboard/Outboard". Regardless, I went with the "Canadian" passenger side (Outboard) and
left the motor unplugged and now the Hippo is running as good as it did before, other that the check engine light staying on due to the unplugged motor.
I am thinking that the worn gear jammed the slide halfway between the two positions resulting in the misfire.
This will be a big week for the Hippo, new ATs on Tuesday and hopefully the new VIS motor Wednesday at the latest. :)
 
I have had VIS motors codes for longer then I can remember, but it definitely does not run on 4 or 5 cylinder because of it. When you mean "like it was" did you mean performance wise?
 
zefrench said:
I have had VIS motors codes for longer then I can remember, but it definitely does not run on 4 or 5 cylinder because of it. When you mean "like it was" did you mean performance wise?
Click to expand...

I have a suspicion that one of the valves has broken loose and is flapping about at certain engine speeds. This can seriously interrupt the air path into the engine. In some cases, it can be bad enough to make the engine feel like it's missing on a cylinder. Locking the valve control rod fully one way has held the loose valve it still. Eliminating the problem for the moment.
The inlet plenum on these engines are very poor quality with valves braking loose regularly.
 
It was an odd problem. My commute home on Friday was longer and driven more aggressively than usual due to rerouting around accidents on my route.
(Mostly highway, some B-roads) When I got home the Hippo was running really well. When I started it the next day it was running on 4-5 cylinders. The code reader indicated problems with cyls 2/3 as well as a VIS issue. This is what led me to think there may have been a fuel problem as the level was much lower than usual.
This is the first time I have had the check engine light come on in the few months I have had the Hippo.
Once I dismantled the VIS the stripped gear was obvious. I reassembled it to keep the slide in the position that Nodge suggested (Thanks again BTW) and the car is running as good as it was before the problems occurred. My thought is that the slide was stuck between the two positions which messed up the airflow to cyls 2/3 but never having had one of these intake manifolds apart I can't say for sure.
Regardless, I'm glad the Hippo is running well again, and it will be good to have the new VIS installed.
I have always had a bit of an issue when I put my foot in it from a standstill. It bogs almost like severe turbo lag. (Without a turbo!)
It will be interesting to see if the new VIS improves the performance.
 
The manifold (the official name is the plenum) is basically two sets of pipes arranged in one unit. There are six long intake pipes, separated into two banks of three. The two banks are linked at one end by a flap valve. This is the balance VIS valve. It's sole job is to allow the two banks to be joined, or separated, under ECU control. The idea of this is to boost torque at set points in the Rpm range. The ECU can make the engine behave like a six cylinder engine, or two three cylinder engines joined together. All depending on engine Rpm and throttle position.
The six long pipes or primaries are there to boost low Rpm torque. However at higher Rpm, long primaries are detrimental to torque. So to improve high Rpm torque, the long primaries have a bypass, controlled by the power valves. These are controlled by the power valve VIS motor. This is again under ECU control, opening or closing the valves as and when needed.
There is a balanced/ power valve table on the manual that shows what is open and when. But the whole assembly is designed to make the engine as responsive and as flexible as possible.

Sadly when BMW took over Rover, they went on a cost cutting binge. The lovely all aluminium inlet plenum on the Rover 800 KV6 was replaced by the cheap German made plastic thing we have today. The problem with the plastic unit is the power valves brake free of there operating lever, so flop about uncontrolled. This hampers the overall effectiveness of the system. Luckily not all the power valves break free at the same time. So most owners don't notice if one brakes free of its control link.
 
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Rich in Vancouver said:
It was an odd problem. My commute home on Friday was longer and driven more aggressively than usual due to rerouting around accidents on my route.
(Mostly highway, some B-roads) When I got home the Hippo was running really well. When I started it the next day it was running on 4-5 cylinders. The code reader indicated problems with cyls 2/3 as well as a VIS issue. This is what led me to think there may have been a fuel problem as the level was much lower than usual.
This is the first time I have had the check engine light come on in the few months I have had the Hippo.
Once I dismantled the VIS the stripped gear was obvious. I reassembled it to keep the slide in the position that Nodge suggested (Thanks again BTW) and the car is running as good as it was before the problems occurred. My thought is that the slide was stuck between the two positions which messed up the airflow to cyls 2/3 but never having had one of these intake manifolds apart I can't say for sure.
Regardless, I'm glad the Hippo is running well again, and it will be good to have the new VIS installed.
I have always had a bit of an issue when I put my foot in it from a standstill. It bogs almost like severe turbo lag. (Without a turbo!)
It will be interesting to see if the new VIS improves the performance.
Click to expand...
Hi Rich, you probably have this - but if not take a peek.
There is some info re checking normal operation and VIS motor and balance valve motor issues.
Also, you may note when reading the dire warning of connecting testbook without the ignition in the correct position possible causing the SRS ecu to be irreperably corrupted.. ! yikes !:eek:

I must confess that when I had my 1985 Toyota MR2 the VIS was much simpler :) - but very effective... The 4AGE 16V twin cam engine used an 8 port inlet for the 4 cylinders. It had a rather nice Variable induction - (Toyota Variable Induction System - TVIS) that had 4 butterfly valves, one in each pair of inlet tracts to each cylinder intake.
at a certain rpm - IIRC about 2k the ecu sent a signal to a vac solenoid that flipped them open. it was excellent.. a bit crude by modern standards but still excellent. -
The VIS assembly was a separate plate that could be removed - unlike the BMW influenced plastic thingies ;)

Hope the pdf is of use if you haven't got it.
It has probably been b^ggered for ages lol :) - it will tear your neck muscles and compress the eyeballs with the new one :D
 

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I hadn't seen that before Joe.
Uncorrectable Corruption! Oh My! Reminds me of the US election.
That's a useful bulletin Thanks!
It was my Power Valve Motor that gave up the ghost.
And Nodge, thanks for the description of the VCU and it's functions.
That is the most straightforward description I have read.
 
Just opened the July 2016 issue of MG Enthusiast magazine and on the Q&A page they have a good little piece on the VIS as fitted to the KV6MG-ZS, including a picture of a VIS with the bottom panel removed so that you can see the power valves. It also has a good write up on the function of the unit.
The poster describes the performance of his car with the VIS removed, and it sounds positive.
There is also an article on a KV6 powered MGF. :cool: They are a bad influence!
 
Rich in Vancouver said:
Just opened the July 2016 issue of MG Enthusiast magazine and on the Q&A page they have a good little piece on the VIS as fitted to the KV6MG-ZS, including a picture of a VIS with the bottom panel removed so that you can see the power valves. It also has a good write up on the function of the unit.
The poster describes the performance of his car with the VIS removed, and it sounds positive.
There is also an article on a KV6 powered MGF. :cool: They are a bad influence!
Click to expand...
Oo I'd a copy of that mag. My favourite MG saloon it ZS180, having had several, including one from new.
I'm still planning on fitting a KV6 into my F too.
As for the VIS system. I fitted an open plenum on my first ZS, in a bit to improve power. It did make a bit extra up the top of the rev range. But sacrificed a lot of low down torque, especially below 2500 Rpm. The VIS system is pretty good at giving torque where it's needed. The best mods for the KV6 is improving port flow, fit 285° Piper cams and make the engine run at a richer 12.5 to 1 fuel ratio. Oh and bin the cats, adding a straight through system.
 
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I went across the border this evening to the land of Trump and Clinton and picked up the replacement power valve motor from the parcel depot.
It's now installed and a quick drive around the block shows good results. The Hippo is running great with much better pickup and the humungous flat spot seems much reduced. It feels like it has a lot more power. For once I am actually looking forward to tomorrow's commute to get a better idea of the performance.
 
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