Ryland3210

OK, here is another draft, hopefully taking everyone's concerns into account (which may be an imporssible dream, but worth a shot): IDLE TPS/THROTTLE BALANCING TUNING DRAFT September 30, 2007 For the following V11 Moto Guzzi motorcycles, made from 1999-2006 V11 Sport, Le Mans, Rosso Mandello, Scura, Tenni, Cafe Sport, Rosso Corsa, Nero Corsa, Naked Ballabio, and Coppa Italia. If you suspect the valves need adjusting, do that first. Here is a link to some good instructions: http://www.geocities.com/motoguzzi1064/Guz...alvesTorque.htm Then make sure the TPS is calibrated to 150 mv at fully closed as follows: Disconnect the synchronization rod at the ball joint on the right side (the side with the TPS sensor), back off the right throttle idle screw using a 2.5mm hex key, and back off the "choke" cam (make sure the choke cable permits full retraction of the cam (it didn't on my bike). Turn on the ignition key, but do not start the bike. Measure the voltage difference between the two outer wires of the TPS. If the voltage is not 150 mV ±5 mV, then loosen the TPS clamp screws and gently rotate it as required. Be careful not to force it against the TPS’s internal stop in the direction of reducing the voltage, which could damage it. Plus or minus 5 mV can be obtained with a little effort. To do the next step, you will need to connect a vacuum manometer (e.g. mercury stick) to each of the two ports on the intake fittings next to the cylinder head. These are normally connected together with a hose, which is to be temporarily disconnected. Next, close both air bypass screws, reconnect the synchronization rod, but keep the right throttle idle screw backed off to put the connecting rod in tension, removing any backlash, and balance the throttle body vacuums at idle using the synchronization rod adjustment. Screw in the left throttle idle screw if the idle is too low to maintain. Do not use the choke for this purpose, because that would put the connecting rod in compression, introducing backlash, causing the throttle bodies to go out of balance. Now adjust the left idle screw for a TPS reading of .521 volts. + - .005 (corresponding to somewhere between 3.4 and 3.6 degrees physical opening, as read by the optional diagnostic software). This accuracy can be obtained with a little effort. (Some riders have been known to also subsequently physically readjust the TPS (not the idle screw) to lean or richen the entire throttle range. However, loosening its screws and offsetting the TPS to a higher voltage, e.g. .539, will fool the ECU into adding more fuel, but it will also fool the ignition timing table. See also the note at the bottom under “Options”) Next open both air bypass screws to obtain the idle RPM at 1100 to 1200 while maintaining balance. Air bypass screws should be open 1/2 turn or more. If not, back off the idle screw to reduce the TPS voltage reading in steps of 15 mv and open the air bypass screws to compensate until they are opened 1/2 turn or more. Check balance at 2000 - 3000 RPM as follows: A When checking balance at 2000 - 3000 RPM, make any fine correction needed using the synchronization rod adjustment, then: B. Check balance at idle RPM. If OK, go to step C, if not, rebalance at idle using the air bypass screws, and go back to step A. C. Disconnect the voltmeter and manometers. Replace the hose connecting the two intakes. That completes the procedure. Once this procedure is completed successfully, future minor changes in idle speed can be made simply by adjusting the left throttle idle screw. Since the throttle bodies have been balanced, backlash between them has been eliminated, and air bypass screws have been properly adjusted to maintain balance at idle, these should be stable for many miles. Options: Use a gas analyzer if available to set the CO level. Use a diagnostic tool or diagnostic software such as Axeone or TechnoResearch's VDSTS to adjust the fuel trim, check throttle angle, RPM, and more. The setting of .521 volts is in the middle of the range of published settings, and has been found to be reliable for stock motorcycles. However, for those who wish to follow specific instructions in their aftermarket parts, Moto Guzzi owners or service manuals, particularly for modified motorcycles, the table below shows the TPS voltage corresponding to various opening angles per the Magnetti Marelli OEM TPS specification. For other settings, here is the formula: 0.1061 volts/degree + 0.150 Degrees Volts DC 2.9 .458 3.4 .511 3.5 .521 3.6 .532 3.8 .553 4.0 .574 4.1 .585

Good point, but look at the numbers: According to Magnetti Marelli's chart for the TPS, in the first 30 degrees of throttle opening, the transfer function is .1061 volts/degree. This results in the following table: Degrees Voltage 2.9 .458 3.4 .511 3.6 .532 3.8 .553 Now the manual's 550 mv is pretty close to 553, but its 465 mv is more than the 5 mv tolerance away from 458. The manual's credibility is suspect. Now if you look at the fuel delivery mapping, the difference between 2 degrees and 4 degrees is small. To review once again, we have figured out that the idle setting of TPS is compensated for by the air bypass settings, and that it only affects mixture at idle, and the first few degrees of throttle opening just off/idle at most. Therefore the effect of the 2.9 degree spec is to lean out the idle and just off/idle mixture relative to the 3.8 degree spec and vice-versa. To see how little this effect is, have a look at the fuel map. So here's my suggestion: Instead of using the previous measured data on TPS versus angle which is only based on one sensor, let's use the manufacturer's ratio and the table above. Since there seems to be common ground on 3.4 and 3.6 among several sources, let's use 3.5 degrees as a target for the amateur. That equates to a voltage of 521 mv. Anyone using that as a target will not be far off the ideal. We can also include the table above for those who wish to follow "professional" recommendations.

More photos from IMOC2007: The chopper, pickup truck cockpit, and a beauty.

The difference is that the closed throttle adjustment is vital to establish the accuracy of the TPS signal to the ECU, whereas the reduction of the idle throttle position in 15mv steps is merely to permit the air bypasses to open at least 1/2 turn. It could just as well be 10 mv steps or 20 mv steps. dlaing has included your recommendation on valve adjustment. I don't seriously object, but it's a deviation from the purpose of this procedure. One could also suggest checking spark plugs and timing, which would also be deviations, etc., etc. In this case, the manual(s) have not been very helpful. The variation and inconsistencies in the various instructions, opinions, manuals is exactly why this investigation into a clear and useful procedure was started. Another example of ambiguity and points out the need for a dependable and clear procedure. If the 238 mv is intended for the throttle closed TPS voltage, it will enrichen the entire range. If the 238 mv is intended for the idle TPS voltage, it will lean out idle and low throttle opening conditions. But then the Power Commander, as I understand its function, can be used to override either condition. See my comments on Todd Eagan's suggestion, and my earlier comments on the interaction between idle TPS and air bypass turns open. I see no reason to change the draft of September 27th. Keep the faith, dlaing. In my book the most recent draft of th 27th is fine. So far, these last minute comments are rehashing issues already considered and resolved.

And now for something completely different! The one on my bike focused the airstream right at my face. I took it off and have been happy ever since.

See post #40 for the derivation of the 518mv. "choke" works fine. If we are asking the tuner to hold to + - 5 mv, then I think it's best to stick to the 518 mv. I agree that the important thing is to get the 150mv. To review, the only effect of having a higher or lower TPS voltage at idle is its interaction with the air bypasses. For example, if the throttle is adjusted towards closed, i.e. lower TPS voltage, then the air bypasses have to be opened more to achieve the idle RPM. At low throttle settings, that means there will be less fuel delivered and a slightly leaner mixture. However, at increased throttle openings, the air bypasses become less significant, so mixture becomes independent of the idle settings. Nothing wrong with nitpicking when the intentions are good.

OH NOOOO! Let's not have another verbal swordfight on this thread. It can get boring. That is better done on the Banter section. Let's keep it simple, and use "choke" because that's a familiar term and is used in the MG manual. The point is, people will know where they can find it. For the purpose of this thread, that's more important than whether it is absolutely correct technically. Synchronisation Rod is a better term-good change. We discussed the variation of TPS readings when the engine is running previously. That's why its easier, and I believe more accurate, for the user to calibrate the TPS and set the idle throttle opening with the engine off.

So what I gather is that between 3800 and 7500 RPM, the gauze filter and cut off lid gave immediate power and torque gains at between 3500 and 7800 rpm compared to Phil's modified airbox with a paper filter, even without optimizing the map for the former. For me, that's the range of primary interest. I still prefer the paper filter with Phil's modification for the reasons you state, but want to clear up my understanding. BTW, I like dirt roads too, but worry about riding on tires designed for the Autobahn.

This version of wording on the CO mixture tuning is good, but it begs the question, "which computer does have the potentiometer", so I think that the notes on that should be included, for those who have the feature.

Ratchethack, of course you're technically correct on "throttle advance". Perhaps "fast idle" would arguably be even more technically correct. Unfortunately my operator's manual isn't. It's called a "choke". For the sake of making it clearly understood by the average rider, as well as the guru's who will have no trouble figuring out what is meant, it should the same terminology should be used, IMHO. On my bike, there was no perceptable variation in the regulated 5 volt supplied to the TPS as battery voltage varied. That's one of the first things I checked. Truly precise and cheap 5 volt regulators have been around since the '80's. If you are seeing a significant variation with battery voltage, I would look for weaknesses in the ground connections between ECU, Battery, Frame, and TPS cable. The + - 5mv tolerance (range, if you will) was given because of difficulties in doing any better with the sensitivity of the TPS adjustment.

No changes in the mapping?

That's good progress! If the battery was the original, and has been allowed to discharge God knows how many times, and for heaven knows how long, it would not be surprising that it has lost its capacity. Now the questions are: what is the date code on the replacement battery? Is it fresh? was it charged properly? If it's been hanging around a shelf and allowed to stay in a discharged state for months, it will have diminished capacity. Some batteries will be damaged if charged at more than 1/10 the amp-hour capacity. That's why Yuasa recommends only factory prepared batteries for this application. Get ready for the speedo cable to fail, unless it's been replaced with the updated version. Maybe Wagner will be kind enough to get one on order and put it on his shelf so he has one the next time someone needs it. It's a real quick replacement, but I'm still waiting for Branchville Motors to get one. Not a huge investment for Wagner to make, until he gets reimbursed by MG for the warrantee cost when it happens. As for me, the Sigma electonic speedo is working great while I wait. I can now confirm it works at least up to 89 MPH on the local back roads. I hope to test it over the ton this weekend!

I did a quick review of the two versions and it looks like they are similar. Dave, Lots of good clarifications, removing ambiguities on terminology. My comments: 1. The 518 mv, which is based on good data and calculations, should stand. (yeah, 7 mv doesn't mean much, but the target should be based on our best information). The + - 5mv tolerance should stay so people know when it's good enough. 2. I don't see that it is important for the engine to be warmed up to balance the air bypasses at idle. Balance will achieved without that constraint, and idle speed can be adjusted conveniently subsequently without disturbing balance. 3. I didn't specify cruise RPM, because different people cruise at different speeds. However, in reaility, the engine will be under load when cruising, so throttles will be open more anyway, so I have no problem with the range you suggest. 4. Under options, I see no advantage to balancing or setting idle speed ONLY at specified temperatures for the same reasons given in 2. above. I didn't come up with the potentiometer adjustment option, available on some bikes, but it seemed to me that it made sense. Why delete it?

A quick note, dlaing: The version you are working from is the draft, not the final version. The final is the one on September 9th. Check to see if there are any differences. If so, make your suggestions on the final version. :!:

Very interesting. Excuse my ignorance, Greg, but please supply the basic conditions: Mod's to the bike, mod's to the mapping, etc. Thanks,

START-UP STAGE The moment in which the starter switch is activated, the ECU powers the fuel pump for several seconds and acquires the throttle angle as well as the the engine temperature. Another interpretation: It is exactly as it says, but does not say it clearly. It's not that it only acquires the throttle angle only at the moment the ignition switch it turned on, it just that it monitors the throttle angle and engine temperature as the engine is being started so that it knows how much fuel to deliver. I suspect the ECU must assume that the TPS has been calibrated properly (it has no way of knowing where the actual butterfly plates are, so that assumption must be true). Therefore, it has no reason to monitor the TPS to establish a baseline before or during starting. Therefore, it not only acquires the throttle angle at the moment in which the starter switch is activated, but continues to do so while the engine is being started and thereafter. I think this is a case of English not being the first language of the author. Hard evidence for this interpretation is that my practice is to set the "choke" before turning on the ignition, and if the ECU used that position as a baseline TPS reading, then all subsequent F/A ratios would be far off.

I agree with all of dlaing's comments, and here are some of my own: 1. In general, use of terminology unique to one English dialect or another risks misunderstanding. Descriptive terminology is clearer. For example, "grub" screw is less clear than "idle adjusting screw". The term "fully home" can be interpreted as either all the way in or all the way out. In my experience in the U.S., it means all the way in until the screw stops. If that is what is intended by "Bring grub screw "N" of the LH throttle body fully home, make sure not to change throttle opening angle", then the instructions are impossible to follow. If it intends to mean all the way out, does that mean until the screw falls out? Assuming that what they really mean is until it just begins to affect the throttle position, it leaves the throttle connecting rod in a position where there is no tension or compression acting on it. That is fine when the throttles are at idle. However, it does not keep the throttle rod consistently in tension, which has the advantage of eliminating backlash in the mechanism and keeping the two throttles more accurately synchronised. Another advantage is that subsequent adjustment in idle RPM can be simply made by adjusting the LH idle screw without disturbing throttle synchronisation. 2. A method which does not rely on special purpose instrumentation, such as the AXONE 2000, is friendlier to the do-it-yourselfer. 3. As dlaing says, it is cumbersome to go through the entire procedure and then check the TPS voltage at closed throttles if it fails. 4. Instructions written in a particular language should be written by an author with the same first language. 5. Instructions should be proof read by someone other than the author. 6. Instructions should be tried by someone other than either of the people in 4 and 5, with the author observing and taking notes, absolutely hands off. If the author has to lay on hands, it means the instructions are not clear. If he has to explain anything, it means the instructions are not clear. The author will not be at the do-it-yourselfer's side. At the end of the day (to use a favorite English idiomatic expression), the procedure in the manual can certainly work, but is likely to be misunderstood, has an error in it, has bad grammar, will take longer, depends on special instrumentation, will not result in as good carb synchronization or as simple a subsequent idle speed adjustment. I rest my case, and trust that we have made a positive contribution to clarity and accuracy.

Thanks Phil. On 1 ©, Yes, there is a big difference in flow efficiency between a sharp edged orifice and a venturi. However, I was looking for your thoughts on the difference between relatively cool air from the snorkels, versus warm air from hole in the airbox. To the extent the holes in the airbox suck in warmer air of lower density, it should reduce performance, all other things being equal. On the other hand, are you saying that the bellmouthed snorkels still cause enough restriction that the holes in the airbox are a plus, even though the ingested air is probably significantly warmer? 2. OK, understood. 3. With your remapping out the extreme lean condition around 3,000 RPM, I have no difficulty believing in a substantial increase in midrange torque (at full throttle). Once again, am I right to assume there was no remapping of part throttle settings, and that the snorkel/airbox mods do not call for any changes in cruise throttle settings?

And how about doubling up on gaskets to make up the difference?

Phil, A picture is worth a thousand words. Thanks. I would like to bounce some ideas off you. 1. I would expect the three holes to ingest warmer air than the snorkels. Suppose the snorkels were simply cut off the airbox. What would you expect the result to be? 2. I gather from your studies, that unless the ECU is remapped to add fuel at high throttle openings, there would be little change in HP. Moreover, if one were lucky enough to be able to spend any length of time at full throttle, the protracted lean condition could cause piston damage. 3. At cruise throttle openings, there would be no reason to change the mapping, because the relatively low air flow rates would not be affected by the reduced restriction provided by the modifications to the airboxl, agreed? Cheers, John

I'll shoot for the Mobil Station in Great Barrington. Cheers, John

What a shame. Is it really closed!? When I was up there I guess only a month or two ago, Marsh said he had two potential buyers that were going to continue the business. Did they just want the customer list and inventory, and is a real estate developer going to put up some more blacktop, traffic lights and shopping malls, like we really need more of those?!

The tuning method was developed because I was unable to find a scientific basis for any of the various methods I found. Manuals are often written not by the designers and engineers, but delegated to second string techs, or worse, marketing personnel, while the engineers move on to the next fun project. At times, one wonders whether the writer actually ever tried following his own instructions. I am not criticising Moto Guzzi's service manual, because I have not read it. This is a general comment. The method is based on engineering physics, not opinion. An important goal was to eliminate trial and error where possible. The setpoints were determined by researching the available data on sensors and measurements made by credible sources on this forum. The method was reviewed and improved by several contributors, and tried successfully before finalizing it. If you prefer to follow whatever the manual says, or have a dealer do it for you, that is your choice. Not everyone has a service manual. If others wish to use this method, they likewise are free to do so. Moto Guzzi also is free to adopt the method as well. It seems to me there is no harm to Moto Guzzi whenever a better way of servicing or enjoying their products comes along. After you have read through the thread in which this method was developed and find any magic or half truths, please point them out so they can be corrected.

Hi Phil, Can you provide a link to the thread where you describe your mod's? Thanks, John

Hey Pete, Are you braggin' or complaining? John