Stepper Motor Test

I have the tank of at the moment so I thought I would check out the stepper motor.
There are 4 pins on the plug, the 2 outside ones attach to one coil of about 50 Ohms, the inner 2 attach to the other coil of 50 Ohms.
On mine the inner pair were open, so it wouldn't be working, perhaps that explains the fast idle?

I don't think these motors are designed to come apart, I'm fairly certain the motor is glued into the aluminium housing.
With nothing to loose mine was coming apart. The end came off and I was able to get the internal parts out leaving the valve behind.
I found the coil wire was broken right at the solder point but it was too short to re-attach so I pulled the motor apart and re-wound the coil.
I don't like my chances of getting it back together, I will have to motor it to wind the screw back in, It may motor if I just turn the bike on but which way?
It needs to move as though opening the valve, anyone know?

Meanwhile I will see if I can source one.

Looking at the motor/valve construction I really can't see what would be better than a simple flush with carb cleaner, the motor seemed to be well greased, it has a small ball race to take up the thrust, squirting cleaner in any of the 3 ports should be all you need to do, it won't get into the motor.

When I get the new valve I will section this one for your entertainment.

Roy,

Being a stepper motor, the probability is that first one coil fires,then the next, repeat. This will make it go in one direction. reversing the sequence will make it go back the other way. You could try 90 or 180 degrees apart to see what happens ( I am thinking 90 degrees). If it doesn't work again, it can be put down to the university of life (I studied there too - might have been asleep during some of the lessons though). The direction maybe critical on the phasing.

From a circuit diagram, A and D are the outside connector pair, with B and C the inner pair, as you say. Without looking at a good one operating with an oscilloscope, it's very hard to tell.

If you need more info on how to do this, let me know and I will try and explain it - do you come from an electrical/electronic background? However, simply firing one coil, then the next fairly quickly, you should be able to determine which way is which, at least to test it. As this does not do a full rotation, it's anyone's guess as to the number of steps needed to go from fully open to fully closed (or visa versa). In normal operation, the stepper would get to its position that the ECU is happy with, and stay there until more command pulses tell it to do something different.

Thanks for the Info, yes I'm a little familiar with how they work but I was thinking I wouldn't be able to switch coils fast enough, any suggestion would be welcome.

Do they reverse the polarity of the coils or simply pulse one then the other, I could do that with a relay and 555 timer?
If I have to change polarity that gets trickier.

this is an i interesting topic, subscribed!

And we need pictures!
For my ecu test bench I got a stepper from a junkyard. Came out of a fiat, and made by marelli, it might be the same as the one in Guzzi's
It looks Ducati uses the same ones as Guzzi:
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I have one like this

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The markings on the GRiSO unit are Magneti  Mareli on the casting 1B06/00  S0066 on the electrical part.
The Guzzzi part No GU 05135830 has been superceeded
new part No  896540
I believe this is common to a whole range of models, GRiSO 1100, 1200, Breva Norge etc.
They are very spendy so look after it!

The other one you have is only part of a valve.

1B06/00 is the part number, the s number must be a week/batch number, not important.

If you can get the part out and in then you can use a ducati part, it could be used in more bikes.

Roy, you could use the 555 to create a pulsed square wave (probably around 25% duty cycle), then a D type flip flop (or even two) with some driver transistors behind to drive the coils.

Drive one from the rising edge, the other from the falling edge of your 555 output.

I would go for something in Hertz range (maximum of 10, but clutching desperately at straws here?). Simply reversing the outputs to the coils "should" reverse direction...

Capice?

maybe a bit late but Guzzidiag has a stepper motor test (not used it yet though)

only one Question: What will happen without this Steppermotor system? The idle may be controlled by a different mapping?

It's main purpose seems to be to control idle speed during warm up but I'd assume it also has an effect at altitude, (Though that may be controlled entirely through the air pressure correction table.). Thing is some of those who have high idle problems fix it by puting a tap in the stepper feed and once warm the stepper can be blocked off to negate it's input to running.

Pete

The older bikes without stepper do have an idle air bypass, the stepper acts as bypass regulation.
Around idle. You can see if it is opened in guzzidiag. The test there works with a running engine, it should change idle revs when test is used.

I fitted a bypass valve but it doesn't work for me (1200 8V). At any point (cold or hot) as I shut the by-pass; the engine progressively gets upset & stalls when it's fully closed (yes, I set the idle balance single screw with the stepper in play). I haven't run the experiment setting the idle balance with the by-pass shut & then opening it though...

Should add (to my signature as well) I'm running Mark's map so lambda off

I belive that the stepper motor is there for warm up mainly and adjusts idle to suit

Roy

Lay your hands on one of these [You must be registered and logged in to see this link.]

I wanted to bench test my stepper. Thus with one of these, a Ducati plug and a USB power supply I stroked the stepper in and out at a range of speeds and cleaned it within an inch of its life.

Bugger still doesn't work properly and I'm loathed to shell out £500 for a replacement at the moment so am likely to go the bypass route

However. I have a theory that all these steppers are essentially the same differing only in how they mount and the pintle on the end.

SO I think if you have managed to pull all the guts out of the body you might be able to switch the pintle plus is screw bit to one of these [You must be registered and logged in to see this link.] and press the whole kit and caboodle back together for about £30

the only reason I haven't tried it yet is be cause I don't have a spare, and a dodgy ICV is better than no ICV!!

Tris

I once tried what happens on a 1200 sport with the stepper disconnected. Well it's not getting batter that way, with irregular idle. Just be brave and try to change the thing, make pictures for us and tell if it worked.
I do this sort of things to educate you all, so now your turn.

I have just bought a secondhand stepper and currently trying to disassemble. The link to the fiat 500 unit looks like what is in the alloy housing as I can see the notches around the body. Once I get further on I'll update.

I ought to say this is my faulty one I removed.

Update - stripped (well almost) the old stepper motor and got the assembly out and found that the Fiat one is not the same. The Guzzi one has a brass sleeve that slides [motored] up and down.

On the casing it has Marelli and Sonceboz Swiss Made.

I am looking to see if there is anything out there that is a match but no joy yet.

Still work in progress, using the connector on the wiring loom you can eject the plunger {pintle] and then pull in the new one [swapped to correct bit].

Issue I have encountered at this point is getting the plunger to retract far enough to be be able to fit it back in the main body.

will continue playing ...

How is this one coming along now Brian?
I had/having my stepper motor give me issues. I was stuck at 1000 rpm +/- 50 all the time. I pulled the motor out and popped it up then drove it in with OTC tool 3320 with the GM 4 pin IAC connector attached. Although it didn't pull in at all at first, (maybe because the internals is stripped?) but I was able to fit an Allan key under the brass valve then used the tool to pull in the motor (after popping it up from the body) now im back up to 1200 rpm all the time. The service light is still on with a code 60 unfortunately.
I have a video of it moving a gm stepper motor, and voltage testing if you would like to see it.
Also, I have test procedures direct from piaggo on how to ensure proper voltages are reaching from the ECM to the stepper.

OK, slight update, I have been a bit lazy in as much I don't like pulling the airbox out on my 1200 as its a pain! I have now been running without the stepper connected to the airbox for about 2 1/2 thousand miles and bike is running OK.

I think that the failure of the stepper motor is more likely to be the motor part than the pin/pintle/sleeve that goes up and down as I can see and hear all the steppers that I play with doing this but when connected to airbox do not perform as expected. So appears to be the motor not controlling up and down correctly. Well that's my thoughts.

I have also been looking for an easy alternative fix to the stepper so that when the stepper motor part fails it is an easy swap out - so the part I have managed to source to try in conjunction is a Ducati Hyper Motard 896 stepper motor (example picture [You must be registered and logged in to see this link.] which has a bolt on motor so easy to clean and hopefully (if replacements motor can be sourced) easy replacement. [It does have different sized orifices]

As I am due to service the bike in about a 1000 miles I shall be playing again with the stepper motors and will update again.

Anyone haver their stepper motor cycle (run) even with the ignition off & key out of ignition? My GRiSO does just that. I have two RC slider on off switch’s in line with the wiring which shuts the stepper off.
This is really queer, if loosen the negative battery cable the stepper will stop cycling. I don’t remove the cable just loosen you the bolt. Strange.

Now Wayne Orwig on WG worked this one out a few years ago but I can't remember what the cause or solution is. Try asking there. I've not encountered it.

Pete