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 Wiring up a VSV Override switch for Rev1 and 2 Turbos. 
Description Scan of original article giving details of how to wire up a manual VSV over-ride using swtich, relay and LEDs
Author BenF Date Sun Dec 31, 2006 6:07 pm Type Text How-To

Category Engine
Viewer Comments [2 - Post your comments]
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Wiring up a VSV Override switch for Rev1 and 2 Turbos.
Scan of original article giving details of how to wire up a manual VSV over-ride using swtich, relay and LEDs
This Article was originally hosted on Kory Yinglings site - however, the site has been gone a few years, and I found a printout I had taken of the details - I made this modification to my old Rev2 Turbo. The wiring around the Relay is tricky to work out, but it does work well.

I used to use this to keep the car in 'low' boost mode for trackdays.

You could also over-ride the ECU and open the VSV to get full boost on cold mornings.




  

 User comments 
Ian Geary: Fri Jan 05, 2007 1:17 pm    

Hi Ben,

I know this isn't your article, but I think you mentioned you'd wired it up, so would you be able to answer a couple of questions and check my thinking?


The blue/orange stripe wire runs from the VSV to terminal B+ on the ECU. The black with yellow stripe wire runs from the VSV to the EFI main relay.

Which wire carries the 12v? and which is the earth?

I.e does the ECU send 12v to the VSV, or does the 12v power come from the EFI relay, and then the ECU wire just earth it - thereby activating the VSV?

I suspect the ECU is the earth, as the 3 way switch basically conencts either the left (override) or right (disabled) terminal with the centre (earth) terminal, and it's by controlling access to earth the switch works.

Describing the operation of the system, is the following broadly correct?

With over-ride selected, the relay would be shut, but the switch would allow the VSV access to earth, regardless of what the ECU was doing. The VSV would be getting EFI power through relay terminal 87a, and the relay would also supply power to the green LED.

With the disabled selected, the relay would open, and EFI power would go out of termial 87, through the red LED and straight to the ECU earth. The VSV would then get no power, as I assume the green LED prevents the 12v going back through it into the VSV. The red LED would only light when the ECU allows earth, ie when the VSV would have been activated, but isn't.

With the switch in neutral though, the relay would still be closed, so power would still be flowing out of relay terminal 87a.

This would light the green LED when the VSV is activated, as the ECU would be giving access to earth. The red LED would not light at all.


Finally, the rev1/2 setup is an on/off signal, but the rev3+ VSV apparenlty gets pulses.

Would this relay/switch/LED setup not be applicable?

I can't see immediately why it would not work.

Thanks

Ian
BenF: Fri Feb 02, 2007 12:43 am    

Ian Geary wrote:
Hi Ben,

I know this isn't your article, but I think you mentioned you'd wired it up, so would you be able to answer a couple of questions and check my thinking?


Yep, will have a go - but it takes some hard thinking to get your head around the wiring ... I installed this mod about 8 years ago now and no longer own my Mk2 so its tricky to nip out and check.

Quote:



The blue/orange stripe wire runs from the VSV to terminal B+ on the ECU. The black with yellow stripe wire runs from the VSV to the EFI main relay.

Which wire carries the 12v? and which is the earth?



A poke around with a Multimeter should confirm - but Black/Yellow I'd expect to find 12v on as it comes from the EFI relay - the ECU usually grounds signals to complete a circuit and operate relays etc.

Quote:


I.e does the ECU send 12v to the VSV, or does the 12v power come from the EFI relay, and then the ECU wire just earth it - thereby activating the VSV?



The latter I believe - the ECU pulls it down to ground.

Quote:


I suspect the ECU is the earth, as the 3 way switch basically conencts either the left (override) or right (disabled) terminal with the centre (earth) terminal, and it's by controlling access to earth the switch works.



Yep, that's right.

Quote:


Describing the operation of the system, is the following broadly correct?

With over-ride selected, the relay would be shut, but the switch would allow the VSV access to earth, regardless of what the ECU was doing. The VSV would be getting EFI power through relay terminal 87a, and the relay would also supply power to the green LED.

With the disabled selected, the relay would open, and EFI power would go out of termial 87, through the red LED and straight to the ECU earth. The VSV would then get no power, as I assume the green LED prevents the 12v going back through it into the VSV. The red LED would only light when the ECU allows earth, ie when the VSV would have been activated, but isn't.

With the switch in neutral though, the relay would still be closed, so power would still be flowing out of relay terminal 87a.

This would light the green LED when the VSV is activated, as the ECU would be giving access to earth. The red LED would not light at all.


I've read your description through a couple of times and sounds to me like you've got it spot on [thumleft]

Quote:


Finally, the rev1/2 setup is an on/off signal, but the rev3+ VSV apparenlty gets pulses.

Would this relay/switch/LED setup not be applicable?


Interesting. I haven't come across Rev3 owners who have had the same sort of problems on cold mornings as Rev1 /2 owners, so as far as I know it hasn't been tried.

In principle, it should work with Rev3s as well - but if this isn't a problem for Rev3s, there's no need to fit it.

HTH!

Ben.
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