Dead stepper motor?

Last week an issue which has been gone fora long time but has happened twice before (years back) has returned  

It started a couple of days ago, the bike started really difficult and then ran at like 900 RPM, seemingly struggling to keep running. For a moment I thought it was running on 1 cylinder. Then the idle was really unstable for a while, and RPM would rise even after letting go of the throttle. This lasted for <5 minutes riding then everything turned back to normal. However since then the idle RPM is now quite high, around 1800RPM according to guzzidiag. But it is quite steady. The ambient temperature here is around 5 degrees Celsius currently. CO trim is set to 1.

I did the stepper motor test in guzzidiag with the engine running but nothing happened. I then cleaned the throttle body from underneath the battery as well as the stepper motor with carb cleaner through the chute above the left intake. However the idle is still high, and the stepper motor test still does nothing.

Has the stepper motor died? Or is this more likely to have another cause (air leak or something?)

ps. I also noticed the plastic cover of the air filter doesn't have a gasket while the parts manual says there should be a gasket? Can that cause any issues? (I mean I doubt it since there is a pretty big hole through which air enters anyway, especially since I took out the snorkel, but just double checking)

ps2. I had 2 stored errors, but as guzzidiag doesn't show how long ago these occurred and I did alot of work on the bike (most importantly new dash) I don't know if they are related. The errors were P0170 and U1601. I'll recheck tomorrow if those errors are back.

Those are 2 obd codes not the Guzzi descriptors
P0170 is the obd code for Fuel Trim Malfunction (Bank 1)
U1601 is a manufacturer specific defined code
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Okay the faults did not return (I rode 300km's over the weekend). I removed the stepper motor tube today from the airbox, and if I blocked that with my thumb the idle would drop to around 1200RPM (it didn't stall the bike). I could feel the stepper motor cycling, so its not broken at least.

I sprayed half a bottle of carb cleaner through the tube with the engine running and this time that seems to have done the trick. Reducing idle to (fluctuating between) 1230 and 1370 but mostly around 1270RPM.

I also reduced the CO trim to 0 instead of 1 as I still don't really know how I should decide what CO trim number the bike should be on.

On a secondary (maybe related) note, I noticed pulling the clutch lever no longer increases RPM. The sensor itself works (I checked with guzzidiag) what could be the cause of that? (not that I need the RPM to rise when I pull the clutch, but just curious)


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ps anyone know what idle stepper controller/base/break numbers mean?

motor-timothy wrote:

On a secondary (maybe related) note, I noticed pulling the clutch lever no longer increases RPM. The sensor itself works (I checked with guzzidiag) what could be the cause of that? (not that I need the RPM to rise when I pull the clutch, but just curious)

Hi Timothy,

If I remember correctly, when running a Beetle map this function of increasing RPM when the clutch is pulled doesn’t apply any longer,

Or maybe I am just talking BS I am sure the man himself will clarify later,

That would explain it! Thanks

Nope. I don't deactivate the idle rise. Timothy, your pics all show that the clutch is out.

beetle wrote:

Nope. I don't deactivate the idle rise. Timothy, your pics all show that the clutch is out.

Indeed, the pics are to show the idle and steppermotor values. But when I engage the clutch guzzidiag does say clutch engaged


edit:

Well this morning I started it and the idle started at around 1800-2000RPM for about 10 seconds or so then quickly dropped to 1250RPM from which point the bike was as normal. During the afternoon when I started it for my ride back it did exactly the same, roughly 10 seconds of high idle then back to normal.  

There is no increased idle for cold starts when the temperature is around 5 degrees Celsius (41°F) is there?

Stepper is showing signs of degradation. Mine did this and it got progressively worse - in the end I was spending as much on carb cleaner as fuel.

Final Solution? I blocked the inlet to the stepper assembly with an 8 mm bolt - haven't had a problem since.

motor-timothy wrote:

There is no increased idle for cold starts when the temperature is around 5 degrees Celsius (41°F) is there?

Yes. Target idle at 5° is 1300. Taking into account the warmup table, it can be 1500 for a few seconds.

beetle wrote:

motor-timothy wrote:

There is no increased idle for cold starts when the temperature is around 5 degrees Celsius (41°F) is there?

Yes. Target idle at 5° is 1300. Taking into account the warmup table, it can be 1500 for a few seconds.

Thanks Beetle. I'll hook up guzzidiag this weekend again to check. Tachometer shows more around 1800 but that could be just the tachometer being a bit off.

Ps. Am I correct in my assumption that a vacuum leak with the lambda probe off would not result in a higher idle? As no feedback is send to the ECU to inject more fuel.

Adding more fuel will lower the idle, not raise it but in this case it's irrelevant if you're running an open loop map as the lambda has no effect on anything, anywhere.

motor-timothy wrote:

Ps. Am I correct in my assumption that a vacuum leak with the lambda probe off would not result in a higher idle? As no feedback is send to the ECU to inject more fuel.

No, a vacuum leak will still cause idle issues.

Take the stepper motor out of the equation. Unplug all vacuum lines from the stepper. Plug off the vacuum nipples on the stepper. You must keep the electronics plugged in. As for the throttle bodies vacuum nipples, what I had done with mine is I ran the the oil breather lines from both heads. I ran the breather line to the throttle bodies where using a T to have in intake of the line going out to the throttle bodies. This burns off any blow by. It also releases crankcase pressures.

Not sure I understand connecting the blow-by comments...the blow-by normally gets burnt by first separating out the oil mist (at the headstock separator & then in the air box itself) & mixing with inlet air going into throttle bodies anyway. I doubt short-circuiting this into the throttle body vacuum pull would reduce crankcase pressure given the restriction of the pipes & I wouldn't want to start accumulating oil in these vacuum lines either as they are supposed to be air/idle control bleed (previously controlled by stepper). Wouldn't it be better just to blank off all the lines through stepper & adjust the idle with the TB air bleed screws (will need more air as stepper won't add any) ?

I was thinking of this the other day. A friend w/G1100 has his blocked off. That makes them like older TB's before steppers. My buddy leaves his air screws closed and has a feeler gauge he sticks in linkage by stop screw for cold idle at a standstill. Once warmed up it idles and runs as it should or he can jump on and go.

Breather systems are completely different on 1100 and 1200.

I had done it to mine. Right out of the head just like a car.
By pass the puke tank, all it does it collect the excess blow by & keeps the pressure in the valve cover for the most part due to restriction of the puke tank. Mine I ran from the heads to actually Y not a T both breather tubes connect to it with one slightly larger hose going back to the where the stepper motor is. Here is where I I used a T main line in two out to the throttle bodies. You can either silicon plug the stepper motor or loop the two & close off the third. As a big twin during a cold start up they are a bit temperamental but nothing bad at all. When the cylinders get heat in them the twins smooth right out. An engine with the internal pressures is not best for them or performance. Look at race cars. The blow by breathers on the valve covers where do they do with them? Either to headers to burn off blow by or they go into a vacuum pump that sucks the blow by into a puke tank. The less internal pressures the better as I had mentioned earlier. Check it out. Research why they use & or by pass a PCV or direct shots into a puke tank or usually back into the engine via the PCV all the pressures stay inside the engine. Not good. But hey, it’s your bike.

Interesting

Dlpannebakker wrote:

By pass the puke tank, all it does it collect the excess blow by & keeps the pressure in the valve cover for the most part due to restriction of the puke tank.

Just a point - the oil/gas mix that goes through the separator (your name 'puke tank') is not all blow by.
Because the Guzzi is a 90º v twin the under-piston volume decreases and increases by a big amount as the engine spins (totally different to a 4, 6 or 8 cylinder motor). That change will blow any straight oill vapour out of the breathers.
If the separator tank is working properly it lets oil drain back to the rear of the sump and the gases and non settled vapours are sucked into the airbox.

If you remove the separator you risk losing a lot of oil back into the thottle bodies and down the pipe.

As regards the separator causing higher internal engine pressures. Long time ago i came across some separators that got blocked with oil emulsion (mayonnaise) but that was in UK winters. Once cleared they did not seem to cause great engine pressure.   You can check if there is high internal pressure by running it with the dipstick loose - it will blow off if the engine is sloppy.


But as long as you are not losing oil and your throttles don't gum up - it is fine ymmv

The way I explained it is the way I have mine & there is no oil usage. The engine idles perfectly when warm.
A GRiSO rider in Australia wanted to see my set up since I elevated the air box completely. He let his breather hoses run under the bike & not burning off any oil residue. He being a mechanical engineer he made a battery box out of stainless. As for the both of us, we like the setup & the quicker rev’s. A Guzzi teck in Harrisburg PA was impressed with how quick it reve’s plus the way it’s set up.
Keep the rubber to the road, watch for people that can’t drive or see.
Doug

??? I take it that's a typo? 'Elevated'-'Eliminated'? Can you explain the theory behind removing the breather system allowing the engine to spin up faster? If the breather system was so restrictive that it was allowing a pressure build up sufficient to slow the piston's decent in the bore on the power stroke you'd pop both front and rear main seals in a trice. If you're running pod filters performance gains will be negligible and it will upset the fueling. Increased engine wear is an inevitable consequence. I'm sorry but to me the whole system and the theory behind it sounds highly dubious.

motor-timothy wrote:

Well this morning I started it and the idle started at around 1800-2000RPM for about 10 seconds or so then quickly dropped to 1250RPM from which point the bike was as normal. During the afternoon when I started it for my ride back it did exactly the same, roughly 10 seconds of high idle then back to normal.  

Well I figured out what caused this issue: I had forgotten to re-attach (or it had vibrated loose) the stepper motor intake hose to the airbox It's all fine now.

Anyone got a picture of the stepper motor in situ or the tube that the carb cleaner is shot down?

Pipe 4

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The Pipe 4 on mine comes out the airbox on LHS just above the TB - not to be confused with the blow-by breather from headstock separator that joins in similar spot on the RHS of airbox but is shown going to LHS in parts diagram....there was a previous owner so could have swapped connections in past.

You can see routing from picture below ....(I fitted a valve in the pipe at one time - then junked it as adjusting it didn't help)

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