STVA problem

[glang]

2006 SV650S and the STVA has been underwater. It was ok to start with but now shows C28 code, doesnt operate when the ignition is turned on and shows low resistance to earth. My question is what will I find if I separate the plastic connection part of the STVA from the metal body? I want to try to dry the internals out but will it be impossible to reassemble? Thanks

[Grant66]

Excuse my ignorance but what is an STVA?

Google says it's a logistics company in Bristol but I'm guessing that isn't what you're asking about.

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[glang]

ah its Secondary Throttle Valve Actuator. Many fuel injected bikes have one butterfly valve in each throttle body operated by the rider and a second operated electrically by the black box except mine doesnt....

[Grant66]

Thanks found it by looking at a bit more bike specific sources.

It was the A that was throwing me off

Heard of people on the GSX forums taking the butterfly out and then ignoring the c28 without any issues. So that suggests you can take it apart and back together, although that assumes the design isn't significantly different or they weren't doing it from the outside.


Checked the service manual and as expected just says throw it away and get a new one





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[glang]

My manual on page 5-21 says Never remove the STVA which doesnt sound good! I have heard of people removing the system completely but dont know how it rides after that...

[Seeker]

You could try disconnecting it from the butterflies to ensure they are moving smoothly - one or both sometimes seize which throws up a C28 error.

The STVA is designed to smooth the airflow into the inlet manifold (and thus smoother running). If the STVA is removed when the engine is "blipped" the inlet vacuum drops, the air/fuel mixture changes and the engine can stall.

Here's a link on removing it:
https://www.svrider.com/threads/guid...v-stva.155708/

[Grant66]

There does seem to be some issues getting the ECU and the valve positions right again after.

Found a few repair guides on YouTube but all are for GSX, where they have removed the STV and striped it down to fix the actuator.

https://youtu.be/wfuXw0nhwh8

Obviously the SV design may differ (although it may have the same warning in the GSX manual not to remove it).



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[Adam Ef]

Is this the thing that Healtech make the servo eliminator gizmo for?

[Craig380]

I reckon the STVA motor and / or linkages have got sticky with being underwater and so the ECU is trying to move them to the desired position but can't because of the stickiness - hence the C28 code.

There's a nut on the front of the STVA motor which you can see by peering under the tank with a torch. Give the short axle just behind that a proper hosing down with WD40, then do the same with all the linkages (it's easier if you lift the tank). It might just free everything off.

[glang]

Thanks for the replies. Ive seen some of the repair vids and as you say seem to be for GSXR and unfortunately the unit looks to be different from my SVs. Those are all one plastic casing which splits in half where on mine the electrical part is plastic which screws onto a metal gearbox however I suppose the internals might be similar.
My mechanical part all looks free when I wiggle it and the low resistance reading indicates an electrical problem...
Believe the servo elimnators available are to do away with Suzukis exhaust valve which some have in the silencer to reduce noise at lower revs (it handily partially closes just at the point where noise level tests are done!)