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Discussion Starter #3
Put it in dealer mode and got C00

So no errors. The bike starts & runs just fine.
 

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Not normal.

Sounds like the secondary butterflies
 

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Discussion Starter #5
Not normal.

Sounds like the secondary butterflies
Do you think they're just stuck or the solenoid is bad?

I'm looking at the parts diagram and I don't see the solenoid, just the entire assembly.
 

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I think it would be a stepper motor on the butterflies, but could be wrong of course. Maybe a limit switch or sensor needs adjusting or has gone bad.
 

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I think it would be a stepper motor on the butterflies, but could be wrong of course. Maybe a limit switch or sensor needs adjusting or has gone bad.
I agree, not normal and probably the secondary butterfly-valve stepper motor which does that prep-to-start jig.

Pull the airbox and check for a wire or hose interferring with the operation of the linkage and that the valve operates smoothly without excess force. Also, look up C29 in the Suzuki service manual where there is a procedure to calibrate the STP sensor range. Sensor output should be ~0.6VDC with valve closed and ~4.5VDC with valve open. If it is out of adjustment the ECU might be over-driving the valve into the stops or something, causing the stutter. It could be the sensor is going bad but I don't know, other than to check the calibration or just replacing it, how to test for that.

I would check the STP sensor as soon as possible because if it is out of whack it probably won't be too long before over-driving the stepper (if that is what is causing the noise) will burn out the stepper motor. If the sensor checks out then, unfortunately, the stepper motor may be on its way out. It is not sold separately from the throttle body and the whole TB is $800.
 

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Kinda hard to monitor the STV's without the Suzuki SDS software. You could see if a dealer around can see any strange things.
 

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Kinda hard to monitor the STV's without the Suzuki SDS software. You could see if a dealer around can see any strange things.
I know that for the Gen1 Wee the only need for the SDS was to lock out the ISC (idle speed control) valve at mid-range to prevent it from interfering with the adjustment of the idle-air screws (i.e. TB sync) when balancing the cyclinder vacuum at idle. There was also a procedure to reset the ISC settings. So this could be done without an SDS.

On the Gen2 and later bikes the ISC function was integrated into the STV controls. It is not clear to me (maybe someone can confirm) that the old reset procedure will clear the settings in the ECU after a TB sync and thus the SDS/Healtech maybe necessary for for the later bikes.

The procedure to check the STP sensor calibration does not involve the SDS (just measuring some voltages with a DVM) so OP can check that without the SDS or Healtech device. The procedure in the manual does not mention use of the SDS. If the STP sensor is slightly out of range (but not enough for the ECU to spike a C29 error code) then instead of finding 0.6-4.5VDC (nominal) for closed/open valve position he might find 0.4-4.3VDC or 0.8-4.7VDC which could be enough for the ECU to drive the valve into its stops causing the stutter.
 

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I bought a set of TB's from ebay for around $65 bucks. Didn't have the servo motor on them.

You can get the whole deal for cheap. Swap the stepper motor only.

 

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My V2 was making a noise, not the same as yours but a not happy noise.

I lubricated all moving parts on the secondaries and the noise stopped.

That is where I would start.
 
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Discussion Starter #12
I pulled the airbox off and made sure there was nothing interfering with the linkage between the valves. I lubricated the pivot points (no difference).

I definitely agree that the motor appears to be partially unaware of the position of the butterfly valves. I left my multi-meter at work >_< waiting on a buddy to bring his by.

Would it be the worst thing to keep the bike running like this? Or am I going to run in to weird cold idle issues / stalling because eventually it'll go way out of whack? Can you get just the sensor? I'm not seeing it except for 'cheap' entire assemblies (as linked).

Thanks for all the help by the way!
 

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You can get just the sensor. Not cheap.

613580-27G21SENSOR ASSY$103.84$96.57
 

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If it was I. I'd get the above set of TB's and mess around until it's fixed.

You can forget about it and see what happens. It's up to you. 🤷‍♀️
 

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Discussion Starter #16
Ok so I followed the service manual and measured the resistance of the secondary TPS. It’s reading 1.3-4.9k ohms which is way out of spec. It’s definitely reading something but I’m pretty confident that it’s being overdriven because the sensor is slightly off.

ordered a new TPS and hopefully that does it!
 

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It's just a potentiometer. Either a 5k or 10k.

Hope it does the trick! (y)
 

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Discussion Starter #18
It's just a potentiometer. Either a 5k or 10k.

Hope it does the trick! (y)
An expensive potentiometer.

Replaced the TPS on the secondary & I'm getting the same result. Not sure if I want to go any further since the bike runs beautifully...Unless someone has a better suggestion other than 'just buy a new throttle body assy'
 
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