IAW5AM - CO Trim & Auto Learn

[tris]

I have a surgey B11 (plus a PO messed with sacred screw) and am reading up about the 5AM ECU in general and something puzzles me

My bike surges at around 3k RPM and as I understand it at those revs the engine operation is controlled by the O2 sensor in closed loop.

I also believe  that the "richness" can be changed across the complete rev range by changing the CO trim up or down (which changes the injector pulse width) as required between +/- 128 (whatever the units are)

So my question is.

If I were to up the CO by some amount, would over time the auto learn function undo that as it would se the O2 level reported by the Lambda sensor and dial the map back to where IT thought it should be. Unless that is I go in to the mapping  (via IAWWriter) and turn the O2 sensor off and run open loop all the time

If it functions as described, I can't see what CO trim would be for 

Any guidance would be appreciated 

[pete roper]

If you are running a closed loop map the CO trim function is inoperative as it always trims to a factor of zero. The only time you will achieve anything by playing with CO trim is if you have an open loop map.

If your sacred screw has been messed with you're buggered from the get go. No amount of 'Fiddling' will get it right. If you're lucky the TPS won't of been messed with so you can look at what it is and then re-adjust to, in your case, 4.6. If the screw has been played with, then the TPS recalibrated and messed with again? You're buggered. Us, with practice you can get it 'Close' but it'll never be right again. I had just such a bike in today. It sneezes even after my best efforts.

Pete

[beetle]

What Pete said. If lambda is active, CO trim is inactive.

[tris]

Cheers both that certainly answers my question.

The good thing is I have time to fiddle with it and since it's me doing it no cost. Who know I might fall lucky and get it in n+1 attempts 


If not - a new set of unmolested throttle bodies it is.

[redrider]

What does the sacred screw control? Would it be possible to disable the O2, balance the TB's and set the TPS as though it were a 15, then enable the O2? I know Pete and Beetle have way more expertise than I. Just trying to understand for future reference.

[guzzisteve]

To reset it if it's buggered.  Working on clean TB's, back off screw to point of just touching to move TB arm. Reset to 4.6. Now screw it in to 9.2 and reset to 4.6. You will be close but may not be exact!!

Just cause the paint is disturbed does not mean it's off.  Sometimes w/balancing, to get it in sync it moves to the point of needing to be moved back down manually. This does not mess things up but keeps it right w/factory settings.
Sacred screw is for idle speed & TPS sync.

[Wayne Orwig]

It is hard to imagine that the idle stop screw could have even an indirect impact on 3000 RPM.

[tris]

To reset it if it's buggered.  Working on clean TB's, back off screw to point of just touching to move TB arm. Reset to 4.6. Now screw it in to 9.2 and reset to 4.6. You will be close but may not be exact!!

That's interesting. I've see a similar process to that described for a Ducati (I said I'd been reading up  ) but not for a Guzzi.

I must say I'm intrigued by just how accurately this is set originally .

I'd take a guess that Luigi in Magnetti Marellis TB factory is told :-
a) get the flow on the LH TB within those two lines on the flow bench gauge by adjusting the sacred screw.
b) get the flow on the RH TB within those two lines on the flow bench gauge by adjusting the length of the TB connecting rod

On a good day he'll get both smack on mid tolerance but on a bad day he'll get one at the max and one at the min.

However MG don't care as they know that the auto learn and/or a TB balance will sort it out.

Just a thought

[redrider]

If I understand correctly, the sacred screw does the same  task as the balance rod adjustment synch knob on the 15M on my V11? I know from fine tuning the Café Sport, a set of vacuum gauges are imperative and the synch knob works well at 3000 rpm and if checked at idle, leads down the rabbit hole of folly. Are there intake vacuum port blanking plugs used on the 5AM bikes? In the ideal world of bench set-up with a known vacuum source it is easy to set and forget. Real world differences between cylinders may skew the bench setting. It took me a couple of days of fiddling to understand the system and get it right. 

[Wayne Orwig]

If I understand correctly, the sacred screw does the same  task as the balance rod adjustment synch knob on the 15M on my V11?

No.

It is the idle stop screw. The sync knob you are free to turn.
Since these bikes have a stepper motor, that allows air in, the idle stop screw can be out of whack, and the stepper motor will try to compensate and mask it. But then you will run into balance issues, and the limits of the stepper and not know why.

[pete roper]

The W5AM doesn't use a MAF sensor. The only way the ECU knows how much fuel to deliver is by interpreting the throttle position and air pressure and temperature. If you arse about with the stop screw/s you alter the amount of air that is getting past the butterflies but there is no way for the ECU to know this. As Wayne says the target idle will, unless something really extreme has been done, be achieved by the stepper but the problem is that with the very small amounts of air flowed when the butterflies are closed the stepper's crude input can still end up with a sub-optimal mixture, the most usual symptom of this is the bike 'Sneezing' back through the TB's at idle.

Once the throttle is open wider the discrepancy becomes less apparent and the bike will probably run pretty well but fuel economy will be impacted.

Steve's suggestion for 'Re-setting' is one of the most likely to succeed to a degree but it is still, unfortunately, far from ideal. It's the very small quantity and nature of the flow at idle that makes the flow bench set up so vital. It took them years to get it close to right at the WM factory, the early bikes were often wildly out of whack! Nowadays they come set up pretty well!

The good news is that there are many sets of un-mollested TB's out there and available nowadays on the Bay of Fleas and elsewhere for comparatively small money. Unless you luck out with your re-setting its robably easier to simply pick up a good second hand set, (Get good pics of the stop screws!) and be done with it.

Pete

[pete roper]

If I understand correctly, the sacred screw does the same  task as the balance rod adjustment synch knob on the 15M on my V11? I know from fine tuning the Caf� Sport, a set of vacuum gauges are imperative and the synch knob works well at 3000 rpm and if checked at idle, leads down the rabbit hole of folly. Are there intake vacuum port blanking plugs used on the 5AM bikes? In the ideal world of bench set-up with a known vacuum source it is easy to set and forget. Real world differences between cylinders may skew the bench setting. It took me a couple of days of fiddling to understand the system and get it right.

Missed this in the middle of the night.

I think there is some confusion here as to which screw is the 'Sacred Screw'.

The one that shouldn't be touched is the one that faces rearwards and the arm from the throttle spindle touches when the throttle is closed. It is a 2.5mm Allen screw and should be sealed with paint.

The screw on the bell crank that is used for adjusting high speed balance faces to the left of the bike and is a flat bladed screwdriver screw but from the factory also has a dab of paint on it even though it's designed to be adjusted. I think someone recently put up a pic on the ghetto highlighting the various adjusters. I'll see if I can C&P it here at some point.

Pete

[Howard R]

The good news is that there are many sets of un-mollested TB's out there and available nowadays on the Bay of Fleas and elsewhere for comparatively small money. Unless you luck out with your re-setting its probably easier to simply pick up a good second hand set, (Get good pics of the stop screws!) and be done with it.

Pete

Could the OP possibly obtain a set of the un-molested ones and then perform some simple measurement, using a small numbered drill for example, to determine the amount of butterfly clearance on a properly set up TB, and then have a method for correctly re-setting a messed-with set?  I know they were set at the factory using a flow meter, but is there too much sample to sample variation for this idea to have any merit?

Just wondering.

Howard

[pete roper]

Try two thou on the left.