(SOLVED) Idle Stepper Readings

[scott_m]

To round out the discussion of idle stepper readings a little more, I think I've "cracked the code." What follows is my best guess - not established fact. (I'm using Diag but I'm confident VDST provides the same readings, albeit using different labels.)

What Diag calls stepper idle break refers to the "step" the motor is on (stepper motors turn their shafts in precise steps), which regulates the amount of air to flow to the TBs, more air at higher steps and less at lower steps -- only Moto Guzzi know the precise amount. I have observed readings as high as 170 when the engine is cold and as low as 50 when the engine is fully warmed up.

Stepper motor base always reads 100, and I think that is the reference point for calculating break values and/or it is where the motor sits when it is not activated.

Stepper controller values appear to be instructions from the ECU to tell the stepper which step to move to. For idle break values above 100 the desired break value is the controller value plus 100 (e.g., controller value of 30 tells the motor to go to step 130). For idle break values less than 100, the desired break value is the controller values minus 156 (e.g., a controller value of 206 results in a break value of 50).

My experience suggests that a break reading of 50 is normal for fully warmed up motor. I'm hoping this information will be useful for members who would like to know if their stepper motor is operating normally.

Common understanding of desired air/fuel ratios at cold versus an operating temperature engine, would indicate that you are incorrect here.

Fuel delivery is enriched, (higher fuel to air) at a cold startup versus leaner, (lower fuel to air) at operating temperature.

Hence, your value of 170 at cold must be LESS air to fuel ratio and your value of 50 is MORE air to fuel ratio.

I have never encountered a stepper motor that functions “partially”. They are always either working, or not. They will also send and register a trouble code to the ECU if they fail.

If the bike starts and holds and regulates an idle, it’s working. If the idle is erratic or unstable, the stepper is dirty and requires cleaning as previously discussed.

I own a Socio-300 Professional Diagnostic System for motorcycle EFI systems. When I have time, I will get some steeper readings off of my 1200 Sport and share them with you.

 

[scott_m]

Taking a quick look at the factory service manual, I found this...

There is probably the same or similar in the Norge Service manual.

I'm positive that the notation of (for 4'', advancement control of 32 steps; for the next 4'', retrocession control of 32 steps and so on for 30'' ) is utilizing angular measurement in the degrees (°) and minutes (') and seconds ('') notation.

I don't know if you understand angular geometry reference so I offer this to help explain.

In a full circle there are 360 degrees °

Each degree is split up into 60 parts, each part being 1/60 of a degree. These parts are called minutes '

Each minute is split up into 60 parts, each part being 1/60 of a minute. These parts are called seconds ''

 

[Wallace J Gingerich]

Common understanding of desired air/fuel ratios at cold versus an operating temperature engine, would indicate that you are incorrect here.

Fuel delivery is enriched, (higher fuel to air) at a cold startup versus leaner, (lower fuel to air) at operating temperature.

Hence, your value of 170 at cold must be LESS air to fuel ratio and your value of 50 is MORE air to fuel ratio.

I have never encountered a stepper motor that functions “partially”. They are always either working, or not. They will also send and register a trouble code to the ECU if they fail.

If the bike starts and holds and regulates an idle, it’s working. If the idle is erratic or unstable, the stepper is dirty and requires cleaning as previously discussed.

I own a Socio-300 Professional Diagnostic System for motorcycle EFI systems. When I have time, I will get some steeper readings off of my 1200 Sport and share them with you.

I'll be interested to hear what stepper readings you get on your 1200 Sport.

When the stepper value on my 2007 Norge is at 130, for example, the hose from the air box to the stepper motor is pulling significantly more vacuum (more air to the TBs) than when the stepper value is 50. It still pulls some vacuum at 50, which is where it sits consistently after the motor is warmed up, suggesting the motor never shuts off air completely, at least on my bike.

 

[scott_m]

I'll be interested to hear what stepper readings you get on your 1200 Sport.

When the stepper value on my 2007 Norge is at 130, for example, the hose from the air box to the stepper motor is pulling significantly more vacuum (more air to the TBs) than when the stepper value is 50. It still pulls some vacuum at 50, which is where it sits consistently after the motor is warmed up, suggesting the motor never shuts off air completely, at least on my bike.

May I please ask how you have determined this? Did you put an inline vacuum guage or are you just utilizing the tip of the finger feel method?

 

[Wallace J Gingerich]

I used the tip of the finger method, and it seemed evident that there was more vacuum at 130 than 50.

 

[scott_m]

Looking carefully at the Steeper base, CL steeper, and Steeper regulator explinations, I'm not sure that all the values are ABSOLUTES, but rather some are RELATIVE values.

 

[Wallace J Gingerich]

Looking carefully at the Steeper base, CL steeper, and Steeper regulator explinations, I'm not sure that all the values are ABSOLUTES, but rather some are RELATIVE values.

Yes, it appears that the stepper base is a variable value -- the Norge service manual shows approximate values range from 70-100. Mine always shows a value of 100.

 

[Wallace J Gingerich]

The rest of the story...

The high idle issue was mostly resolved, but would still go up about 200 RPMs when sitting idling in gear with the clutch pulled in. I found the clutch switch wasn't working as it should. The stub on the bottom of the clutch lever would engage the switch, but not enough to activate it. I didn't find any adjustment on the switch, so I slipped a piece of vinyl hose slipped over the stub (see photo) and that was enough to activate the switch. This seems to have eliminated the "inoperable" switch problem, at least for now.



I'm curious whether the slight increase in idle speed when the clutch is released with the bike in gear is accomplished via the stepper motor or the ECU (or both).

So to summarize, I resolved the high idle problem on my 2007 Norge by doing the following:

1. Thoroughly cleaned the stepper motor and hoses, and lubricated the stepper with silicon spray while activating it.

2. Removed and thoroughly cleaned the throttle bodies, bleed screws and passage ways.

3. Meticulously synced the throttle bodies and reset the TPS. Prior to cleaning the TBs and stepper motor I don't think I was able to get a good sync on the TBs.

4. Adjusted the non-functioning clutch safety switch.

Now everything seems to be working as it should. Although closing off the intake to the stepper motor may take care of the high idle problem, I prefer getting the systems to function as they were designed. I suspect the increase idle speed when releasing the clutch is done with the stepper motor -- if so, closing off the stepper would eliminate this feature.

 

[Kevin.NZ]

You are correct that the stepper motor alters the idle, I have a valve on my stepper motor and when the stepper is shut off the idle does not rise when the clutch is operated

 

[KERMUTT]

The rest of the story...

The high idle issue was mostly resolved, but would still go up about 200 RPMs when sitting idling in gear with the clutch pulled in. I found the clutch switch wasn't working as it should. The stub on the bottom of the clutch lever would engage the switch, but not enough to activate it. I didn't find any adjustment on the switch, so I slipped a piece of vinyl hose slipped over the stub (see photo) and that was enough to activate the switch. This seems to have eliminated the "inoperable" switch problem, at least for now.

View attachment 18732

I'm curious whether the slight increase in idle speed when the clutch is released with the bike in gear is accomplished via the stepper motor or the ECU (or both).

So to summarize, I resolved the high idle problem on my 2007 Norge by doing the following:

1. Thoroughly cleaned the stepper motor and hoses, and lubricated the stepper with silicon spray while activating it.

2. Removed and thoroughly cleaned the throttle bodies, bleed screws and passage ways.

3. Meticulously synced the throttle bodies and reset the TPS. Prior to cleaning the TBs and stepper motor I don't think I was able to get a good sync on the TBs.

4. Adjusted the non-functioning clutch safety switch.

Now everything seems to be working as it should. Although closing off the intake to the stepper motor may take care of the high idle problem, I prefer getting the systems to function as they were designed. I suspect the increase idle speed when releasing the clutch is done with the stepper motor -- if so, closing off the stepper would eliminate this feature.

I totally appreciate your in-depth involvement in trying to figure out how this stepper motor works. I have the same mindset. I want to know how it works. although I will be putting a valve in it to shut it off as that's what Todd recommends once I have the fuel map changed with the addition of the power Commander setup.
I'm actually smack dab in the middle of a whole series of modifications and that stepper motor was one of the things that I was curious about.