Guzzidiag question & Stepper Idle

I’ve mentioned sometime back my GRiSO idles around 1,000 at start up and maybe gets up to 1100 when it’s been ridden for quite some time. Don’t get me wrong, the bike runs great. When I hooked it up to guzzidiag last weekend I saw a measurement I guess I never really looked at which is the “idle speed calc”. It showed 1200. I presume that’s telling me what it should be? Would like to understand what that measurement means.
Many thanks!

That is the target rpm for stepper motor I think. At least I remember such a thing.

The map has a "target idle" table. RPM vs Engine temperature. The ECU uses the stepper and idle fuel table to reach the "target".

Thanks Steve and Mark.
I’m running the Beetle Map for the stock pipe although I’m now using the MIVV pipe.

MIVV without a cat? dB killer in?

Mark,
I don’t think it comes with a cat and I haven’t modified it. Db killer is in and it’s no louder than the stock muffler.

So I’ve got a real strange one here. Hopefully someone here has run into this occurrence.
Beetle has been helping me and we’ve even tried another map to no avail. The stepper seems to be working and makes all its normal noises upon shutdown. When I take the hose from the stepper to the airbox lose, the idle immediately goes to 1250 from 1000. I shot some throttle body cleaner through the hose while the bike was running a couple of times, which stalled the engine. But this is how I learned that it will idle properly if disconnected from the air box. So I checked the spigot on the air box and blew compressed air through it- no problem. I opened up the air box, took the filter out, had the access door behind the battery open, basically no restrictions and connected the hose again and it would idle at 1000 but as soon as I pull it lose, it goes back to 1250. The connection seems to be the issue but why? That’s the mystery…..

I went in to "Actors" in guzzidiag and performed the Engine running stepper test. There was no reaction relative to a change in RPM's whether or not I had the stepper hose connected to the airbox or not. So, I ran it when the idle was 1250 (hose disconnected) and then again with hose connected and idle 1000. Both times it was like I didn't do anything. Of course I have no idea what this means............maybe something to someone here. I do hear the stepper noise each time I turn off the engine. And when I was disconnecting the hose I found this little guy in there just sitting on the engine (MG logo piece) I put a crush washer next to it from the gearbox so you can see the size. I'm sure it's not part of the problem....

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Although I am not technically smart enough to help you with your idle problem, I can tell you that the little disc with the MG logo you found comes from your master key. Mine has always been missing ever since I bought the bike and I wonder how it ended up sitting on your engine . . .

Right. I did for science and grins.

Connect GuzziDiag. In Measurements, set the drop-down next to RPM as "Idle stepper controller".


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Start the engine. In GuzziDiag, select Actors, and on the "Engine On" side, pick "Stepper (Idle control)"


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Click start, then go back to Measurements and watch the RPM and Idle Stepper controller values. They should go up and down together.

Got it. Thanks Mark will try this today.

Ran the test and the RPM would change and stay in the 900's but the idle steper controller stayed at 100 and didn't fulctuate.

OK, so the stepper is working. Now need to figure out why there's not enough air getting through.

You mentioned you cleaned everything except the spigot? Maybe check inside the airbox or use compressed air to see if the spigot is blocked.


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Thanks Mark. Yes I already shot compressed air through it. I had previously tried to poke a zip tie through and it wouldn't go but I think the spigot on the inside has a 90% bend or something which is why I shot the air through. The spigot doesn't seem to go straight through.

This is vexing. I'm terribly vexed.

If removing the hose from the airbox allows a 1250 RPM idle, and connecting makes it drop to 1000 RPM, then the only conclusion is that there's something in the airbox spigot vent reducing the flow, or the airbox has less air in it than expected....like a massive vacuum.

I’ll see what I can learn about the spigot in the air box. Compressed air went through but maybe there’s a restriction. I couldn’t push a long zip tie through. Feels like if it had straight access through, it would be ok. I had a completely open airbox access door and no filter and it still wasn’t getting enough air when I’d connect it.

Took it apart again and the spigot goes into the airbox and makes a turn (maybe 90 degrees).
This is why I can't push something through except air. Did the compressed air again. Seems slightly restricted. The stepper hose just seems like it's not getting enough flow through. Disconnect it and its at 1250 again (done this about 3 times so far...) I took the hose lose and put my finger over part of the opening to see how blocked it could be until it starts the low idle. Answer is about half.
I tried to pull off the spigot on the inside of the air box but no luck (at least without taking the airbox out completely). it may be molded plastic on the inside, it's hard to tell.
I am also vexed...............

I was able to push a cable tie through on one of my spare airboxes. There could well be something in yours.


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Can you see if it’s possible to pull off the spigot on the inside. Can’t thank you enough for doing that test.

As you can see from this pic, it looks to be plastic welded in. I'm not sure I'd want to remove it. Forcibly removing it may damage the airbox. A dremel might be best to remove it..if you really wanted to. Or simply drill from the outside through the spigot?



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So I dinked with the airbox some more and I don't know if its made differently than the spare you have, Mark, but this one makes a turn between the outside spigot and the inside spigot. I can't push anything through. I tried a small flexible wire, wire tie etc. I even tried an awl and everything hit the wall (turn point) and wouldn't go further. I tried from both directions too. I put through 120lbs of compressed air and it doesn't feel like there is really a restriction that somehow manifested itself. This is just how the airbox is made. So he's my next question; it appears the stepper is working because of the test and I can hear it when I turn the bike off and it will keep it at idle when the stepper hose is disconnected, but.....is it possible that somewhere along the way the stepper has decided it needs more flow?
And, finally, idling at 1,000 to maybe a little more, isn't that bad. The GRiSO is still awesome.

If you ran a drill up through the spigot, would it enter the airbox, or make a hole somewhere else? I would try it, and see if it cure the issue. Easy enough to patch if needed.

JohnA wrote:

I don't know if its made differently than the spare you have, Mark, but this one makes a turn between the outside spigot and the inside spigot. I can't push anything through.  

No, they're all the same. They have a 90 degree bend. My 2nd spare airbox is the same.


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When I modified the airbox that's in the GRiSO now for the single throttle body, I cut that end off. It's somewhere in the pile of GRiSO & Guzzi & Aprilia munt I have. If I could find it, I'd use it to test drill the spigot for you. Alas, I cannot find it.

Nothing more is needed. Let me ponder Rick’s idea. I do have JB weld to fix it if it doesn’t help, which I kinda believe it should.
Many thanks!

The mystery MG logo badge is off the ignition key.


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