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what the heck is a stepper motor

A stepper motor controls the idle on more advanced FI systems. Its controlled by the ECU and will increase the idle if it detects a cold start (it comes into play at other times, too). It basically just has a shaft that pushes on a cam in the throttle linkage. I'm pretty sure your Stelvio has one.
 
pokeyjoe said:
A stepper motor controls the idle on more advanced FI systems. Its controlled by the ECU and will increase the idle if it detects a cold start (it comes into play at other times, too). It basically just has a shaft that pushes on a cam in the throttle linkage. I'm pretty sure your Stelvio has one.
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Thanks, i will look for it next time i have the tank off I have looked for it in the w/s manual but couldnt find anything ,[but then again the manual doesnt say a thing about the fuel filter either!]
 
The stepper motor is essentially an electronic air valve that is ECU controlled. It pumps air to control idle, and is never completely off. Some earlier Griso and Norge had issues with high idle because of it. Your Stelvio has one. I offered a kit which shows the stepper motor here; https://www.guzzitech.com/tech/electri ... ow-to.html
 
GT-Rx said:
The stepper motor is essentially an electronic air valve that is ECU controlled. It pumps air to control idle, and is never completely off.
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Thanks for the rescue, Todd. Obviously, the ones I've worked with are different, but the end result is the same (sorta).
 
GT-Rx said:
The stepper motor is essentially an electronic air valve that is ECU controlled. It pumps air to control idle, and is never completely off. Some earlier Griso and Norge had issues with high idle because of it. Your Stelvio has one. I offered a kit which shows the stepper motor here; https://www.guzzitech.com/tech/electri ... ow-to.html
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I like that you used Posi-Lock connectors. That's a sure sign of a quality approach.
 
Ad B said:
You wrote "I offered...". Is your kit still available or not any more?
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I might have enough components to do a few more, but what I do not have is the switch pod, so you'd have to source or make something to hold the switch. There are other simpler options here on this Forum as well.
 
The stepper motor on my 2011 Norge is being or actually was replaced under warranty today, I'm hoping that it has fixed my cold start issue. When the bike is cold, it won't start with out me pumping the throttle, once it has started and idling for about 15 seconds of throttle control, it idles just a little rough at first then settles down to a nice purr. I'm sure hoping this is the issue, so I can concur that it does assist in cold starting, lets hope :roll:
 
evo said:
The stepper motor on my 2011 Norge is being or actually was replaced under warranty today, I'm hoping that it has fixed my cold start issue. When the bike is cold, it won't start with out me pumping the throttle, once it has started and idling for about 15 seconds of throttle control, it idles just a little rough at first then settles down to a nice purr. I'm sure hoping this is the issue, so I can concur that it does assist in cold starting, lets hope :roll:
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In cold weather; under 40 degrees F; my Griso 8V is acting just like you describe your Norge.
Did replacing the stepper motor fix your Norge ?
 
This is something I'm wondering about and Danny at Fasttrixx is looking into now. My bike has developed a close to sta lling issue stopsigns and has got me thinking stepper motor. So, it actually has an airline? Be nice if it was that simpl, like a clogged or broken airline.
 
Doug,
I'm not an engineer but this is how I understand the system to work: The stepper motor controls air being bled into the intake tract. Without the air bleed the engine will run richer, much like a choke on a cold engine. As the engine warms up it can run less rich so the stepper motor starts to add a bit of air to the intake tract (in steps...hence the name stepper). Once the motor is fully warmed up the stepper motor is all the way open. The kit from GuzziTech allows you to keep the stepper motor in the fully open mode all the time.

Peter Y.
 
The stepper motor adds air to raise the idle. This aids in cold starts and maintaining the idle while the motor is cold. It works much like a manual fast idle (we still tend to call it choke) lever on the previous versions of FI, like the V11. The stepper motor adds the extra air, the ECU likely adds the extra fuel to go with it. As the motor warms up the steeper does not need to add as much air. I do not think it ever fully closes, but it is less use as the motor warms up.
 
pyoungbl said:
Once the motor is fully warmed up the stepper motor is all the way open. The kit from GuzziTech allows you to keep the stepper motor in the fully open mode all the time.
Click to expand...

I would think exactly the opposite is occurring. The stepper motor works well, but is responsible for abnormal high idle in many cases, which can be cured by closing the air line that feeds the stepper motor. I have a pneumatic switch on three of my Guzzis (all 1200 Sports) to address this issue.

A side benefit is with the stepper motor disabled, the engine braking is more pronounced and predictable. Makes throttling off into corners a real pleasure (but of course not as much pleasure as accelerating out.) :evil:
 
GuzziMoto & kiwiDave...you guys are probably correct, either way, the stepper motor controls air bled into the intake.

Once again, I'm not an engineer.

Peter Y.
 
I have a manual valve in the line for the stepper motor. If I turn the valve OFF, the bike will not idle when cold. It needs to add the air when cold.
Once warm I can turn the valve off it it will idle fine. The reason I have the valve is because while the stepper motor is not required for idle when warm, for emissions reasons they have the stepper motor adding air when you shut the throttle from higher revs. I assume this is to help prevent unburned fuel from going through the system. But it leads to less engine braking and a slower drop in engine revs, noticeable to me while shifting.
 
Hi GuzziMoto,
GuzziMoto said:
I have a manual valve in the line for the stepper motor. If I turn the valve OFF, the bike will not idle when cold.
It needs to add the air when cold.
Once warm I can turn the valve off it it will idle fine. ...
Click to expand...
When your engine is warm, how many revs is it idling?
I have the same fuell valve installed on my G12 as you have.
With the first drive yesterday, it worked fine.
Minimal popping with de-accelleration, that was my main reason.
But it's only idling at less than 1000 revs, this is to low.
So, when possible, I still have to work on my love.

Ad B
 
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