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Advice needed on sick Stone please!

Discussion in 'Loop & Tonti' started by Gwilliam, Jun 22, 2020.

  1. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    The curve seems steeper on the spec sheet but we don't know the scale of the X and Y axis. I can't make out the text. See if you can darken the text to make it readable. As for the numbers after PF3C I don't know what they mean.
     
  2. V700Steve

    V700Steve High Miler GT di Razza Pura

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    I've used the HD one at least 5 bikes w/no bad effects. The curve is so close you can't feel any difference.
     
  3. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

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    Hi John,
    This is what the text says in the photograph:

    PF3C Test Report.
    The PF3C is a non-linear TPS, with steep rise for small throttle opening, for best resolution during real world riding and has a less discernable rise towards WOT.

    This TPS's angle to voltage response curve.

    (The graph is then shown)

    Test date: 2016-03-17 11:54:30 The test above has 118 data points from 0.103 to 4.976 VDC, by 10-bit ADC. Each data point is 0.750° apart. Total rotation is 88.5°
    Steep initial slope:
    Avg rise per point: 16.58 ADC. or 0.081V
    Min rise between points: 8. Max: 25.
    Std dev of ADC rise between points: 2.986
    Std dev values under 3.00 are outstanding!
    Knee occurs at 30.8° Gradual WOT slope:
    Avg rise per point: 4.42 ADC, or 0.022 V
    Min rise between points: 0. Max: 9.
    Std dev of ADC rise between points: 1.216
    Std dev values under 2.00 are outstanding!
    Firmware: tps_bench v1.13

    ca-cycleworks.com
     
  4. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Not sure I can compare the two based on the information from the spec sheet. It does look like the cyclewerks TPS does increase voltage more rapidly than the Marelli unit, but I can't be positive on that. If anything it will make low range a bit richer than the Marelli unit and top end about the same.
     
  5. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

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    In the recent 2003 California Titanium thread by Hydrolastic he wrote the following:

    Got my Carbmate today, so I set about tuning things up. It turns out the throttle bodies were well balanced, but the TPS was off. The TPS part was the most complicated part. The connector on my bike does not have a rubber boot that can be pulled back to probe the wires. I ended up partially straightening a paperclip to get gently past the weather seal. I found it was at .440 mv. I decided to set it at 0 deg just to make sure I had a good point of reference. I can safely say the TPS had never been touched, because there was so much of the tamper detection paint on the screws that I couldn't get a bit in to loosen them. I had to chip and scrape it out. I set it at 150 mv, then turned the idle screw until it read 540 mv, which lined the throttle linkage up perfectly with the untouched right side throttle, so all good there. The low RPM performance is definitely better. It doesn't feel like it leans out when I take it just off idle anymore, doesn't surge as much at part throttle, and it is still smooth above 2500 RPM. The idle still seems a little low, and I ended up setting the air valves at 1/2 turn vs. a full turn, because that is where they were to start with and it ran better there in the end. I'll probably just bump it up a little, it's only a hundred or so RPM low, but I want the idle at least at minimum to keep oil flowing in the PI engine.

    I was interested to read the above, particularly the section about curing the leaning out just as he takes it off idle and smoothing the part throttle operation.
    This appears to have been achieved by setting the L/H throttle body idle screw to a value of 540mv, to match the untouched R/H linkage, rather than the correct 520mv.
    I have heard of people adjusting the tps slightly to make the engine run richer throughout the fueling range but does increasing the idle stop screw setting have a similar effect?
    My Stone is 95% sorted but still spits back through the inlet more than it used to as I transition from overrun to drive. I feel that it is also too lean at this point.
    I am currently running the BG44 through the fuel system with the highest available octane petrol but so far it hasn't solved the problem. I am therefore considering rechecking the tps settings and experimenting a little with the MV values to see if I can achieve the desired result.
    All input from anybody that has experience of this problem would be very welcome!
     
    Last edited: Jul 26, 2020
  6. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

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    The best substitute probe is not a paperclip! That can easily damage wires.

    The best thing is a very fine steel sewing needle. Slides in and out clean with no damage or tearing.

    Cheers!
     
  7. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

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    Hi Scott,

    After perforating the two wires several times with fine sewing needles, I realised that I needed a better solution to provide the necessary access in order that I can easily check the TPS voltages. I therefore shaved a small section of the insulation from each of the wires and soldered a short section of red wire to the positive and black to the negative. I fitted insulated terminals to each wire, to which I can easily connect my digital volt meter.
    I have reset the initial closed butterfly setting to 150mv after discovering that it had changed to around 130mv, causing the weak mixture and retarded ignition condition that I was experiencing. I have been playing with the 520mv setting but it has been complicated by a recent battery failure. I understand that the regulated 5 volt output from the ECU should mean that the TPS voltages should be consistent but I will be happier double checking the results with the new battery.
    I am now easily able to check the value with the engine running as well, currently 521mv.
     
    tobinh likes this.
  8. vagrant

    vagrant High Miler GT Contributor

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    he meant to slide the needles in where the connectors are not puncturing the wire. you might have lanced it in half.
     
  9. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

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    Yes, I realised what he meant but I found it difficult to make a reliable connection that way. It is also more awkward than using the two pick-up leads that I have now installed.
    I work with wires on a daily basis so it was not too tricky to shave off a small section of insulation to expose enough copper to solder on the new leads. I didn't want to cut the wires and rejoin them all in a connector to avoid any additional resistance from corrosion in the future.
     
  10. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

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    That’s another more radical solution for sure Gwilliam, but hey if you have the mad soldering skills to do that, more power to you.

    For me, my whole life I have one hard and fast rule and that is, I NEVER cut into or modify an existing factory wiring loom. That’s just me.

    I will run complete new circuits if need be to avoid hacking a loom.

    Kudos to you on your inventive solution!
     
  11. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

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    I'm not sure how radical it is - I didn't have to cut into the loom. There are 2-3 inches of exposed wires between the end of the loom sleeve and the ECU plug, so it was easy to attach two lengths of wire at that point.
    As I have had to connect to those two wires several times recently, I felt that I needed to provide an easy access point without the risk of damaging the wiring by piercing the insulation with needles.
    By making the process as easy as possible I am able to check the TPS setting more often until I can smooth out the lean mixture/retarded ignition condition that has been annoying me. I just wish that I had taken a note of the settings before disturbing the original TPS but that's the benefit of 20-20 hindsight!
     
  12. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

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    :wait:

    TPS has nothing to do with “the lean mixture/retarded ignition condition”.

    A TPS reset provides ZERO THROTTLE POINT BASELINE ALIGNMENT (firmware to physical operating conditions) alignment of the fuel injection map to the physical location of the butterfly valve position. It is done so that the FI map is correctly aligned to actual real world position of the throttle-bodies.

    TPS reset is only done after physically moving the positioning adjuster on the left side throttle body.

    I don’t think you understand the relationship and function correctly.

    May I suggest reading

    https://www.guzzitech.com/forums/threads/syncing-throttle-bodies-stelvio-8v.9082/page-2#post-151363

    :nod:
     
    Last edited: Aug 5, 2020
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  13. V700Steve

    V700Steve High Miler GT di Razza Pura

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    I saw a pigtail that goes in between TPS and wire loom for checking wires somewhere on a forum. No more pins & wire clips. Can't remember where I saw it though, pretty slick deal. Makes setting easy.
     
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  14. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

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    Hi Scott,
    When I mentioned the lean mixture and retarded ignition condition I was referring to the fact that I had originally set the tps at a value of 150mv before continuing with the idle stop 520mv setting etc. The bike gave all the indications of a lean mixture and/or retarded ignition timing. It was spitting back through the inlet tract and air filter and detonating as load was applied particularly in higher gears.
    When I rechecked the settings I found the tps initial setting was only 130mv which would give the lean mixture/retarded ignition timing condition as the ECU would be supplied with a signal suggesting that the throttles were not as far open as was actually the case.
    It would therefore only supply the smaller volume of fuel appropriate to the indicated smaller throttle opening: the ignition advance would be reduced in the same way.
    I believe that some riders intentionally set the baseline value of the tps to a higher figure to richen the mixture throughout the range, by adjusting the fuel map to a higher position relative to the throttle butterfly position.
    Having now reset the tps correctly and using a higher octane fuel I am now free of detonation and the induction backfires are few and far between.

    I have read your suggested thread on synching the Stelvio throttle bodies and consider myself fortunate that I have an older California that allows me to get away with just a DVM. Obviously a Diag tool would be beneficial but is not readily available to me and I suspect would be a cost difficult to justify for the number of times that it would be used.
    Thanks as usual for your input, it is appreciated.
     
  15. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

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    A short update for anybody still interested in this saga!
    I haven't had a lot of time or opportunity recently to experiment with the fuelling of this bike. However, I have noticed a variation in the TPS voltage as the throttle closes fully, when setting the initial 150mv. This can be induced by rocking the L/H throttle body linkage, suggesting some play between the throttle spindle and the body.
    This may not only cause an air leak just as the throttle is opened but also change the voltage supplied by the TPS to the ECU and hence the amount of fuel injected. Either or both of these conditions could cause a momentary lean mixture as the throttle spindle moves from a closed position, resulting in an occasional spitback through the air filter.
    I have read of problems with worn seals between throttle bodies and spindles on various forums. These have been blamed for premature failures of throttle body sensors, due to the unusual vertical spindle on Moto Guzzis allowing fuel to leak down into the sensor. This fuel can also dissolve lubricants and damage the material of the spindle seals.
    Some owners claim success in replacing leaking seals with appropriately sized viton "O" rings.
    Whilst I am reluctant to interfere with it at the moment as it is behaving pretty well, I will spray carb cleaner around the spindles whilst at idle and monitor the effect. The results will dictate whether I attempt to strip and rebuild the throttle bodies over the winter.
     
  16. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

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    Friendly warning.

    The throttle bodies are calibrated on a flow bench at the factory and sold like that.

    Removing them and altering them will most certainly give you a bike that will no longer run correctly.
     
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  17. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

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    Hi Scott,

    Thanks for the warning. I can see where you are coming from regarding the factory set stop plate throttle screw, on the synching the Stelvio throttle bodies article that you recommended reading earlier.
    However, I don't believe that the California is quite as sophisticated or fussy. The throttle bodies may be set up at the factory but presumably that is for a new bike and twenty years and thousands of miles later those settings may no longer be so accurate.
    If I identify leaking throttle spindle seals then I need to fix them as that is not what the factory intended either. As soon as I opened up the intake and exhaust systems I screwed with the factory's settings and had to install a PC111 to compensate. Fortunately, I have access to some good used throttle bodies that still have the yellow anti-tamper paint intact. If all else fails I can use those!
     
  18. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Gwilliam likes this.
  19. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

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    Oh I understand the procedures fully. I own a California Vintage.

    I just offer caution and nothing more. It’s your bike to do with as you wish.

    I just think you cannot resist tinkering or looking for issues. It’s ok, just very unusual to me.

    You may now return to your normally scheduled programming and I’ll shut up now....
     
    Last edited: Aug 23, 2020
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  20. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

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    Believe me, I would rather ride it than work on it!
    I have owned this bike for over twelve years and have done little to the engine apart from servicing and the "bolt on" intake and exhaust modifications.
    I am not "looking for issues", I am looking for a solution to an issue that has made itself very apparent!
    It appears from the following link that I am not alone with this problem:
    https://www.guzzitech.com/forums/threads/throttle-shaft-wear.16838/

    This all started with my inability to diagnose the failed TPS. That led to swapping a lot of parts, based I believe on a logical process, before learning about the random nature of TPS failures. Ever since installing the new TPS I have suffered with an intermittent spit through the air filter as I begin to open the throttle from over run.
    I have followed the listed TPS setup procedure which involved adjusting the idle stop screws, in addition to the air bypass screws.
    During this process I identified lateral play in the L/H throttle spindle, which affects the voltage output from the TPS. Potentially, it is also causing an air leak as the throttle spindle moves from its stop to an open position.
    This is the point at which I am getting the misfire. I don't think it is unreasonable to address this problem.
    I can either replace the original throttle body or attempt to repair it. The repair option seems like the first step to me. That involves dismantling sufficiently to identify which components are worn and whether a repair is possible.

    I thank you for your concern but I have little to lose in inspecting my existing components. I am not an authority on these bikes and maybe the later CalVin that you own has a closed loop system requiring observance of the "Sacred Screw" adjustment.
    My more basic 2001 open loop system is possibly more forgiving, allowing the use of a digital volt meter and vacuum gauges for all but the idle CO adjustment.
     
    Last edited: Aug 26, 2020

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