Ridemalibu Motorcycle Rentals & Tours – Los Angeles CA
  1. Ciao Guest - You’ve landed at the ultimate Guzzi site. In SoCal? See the SERVICE tab above for the best in service, tires, tuning and installation of our products or custom work. NEW FORUM REGISTRATIONS REQUIRE EMAIL ACTIVATION - CHECK YOUR SPAM FOLDER. ALWAYS TRY A SEARCH BEFORE STARTING A NEW TOPIC - Most questions you may have are already answered on the Forum with FACTS, NOT OPINIONS. PLEASE DON'T BE A DRIVE-BY POSTER: As a common courtesy, check back if you are posting elsewhere on the web. Note there's decades of Guzzi hands-on experienced help on this site, all whom give endless amounts of their time for free; BE COURTEOUS AND RESPECTFUL! There is zero tolerance on personal attacks and off-site links to other Forums or competing products. Also be sure to click on the STORE link also above for our 600+ product inventory, including many of our 100% Made-in-house-USA GTM products and engine kits. We appreciate the consideration, understanding and your business... past and future. And if you haven't seen our MotoCycle (not) art, click on the BUILDS tab above to see our work at our sister business; GT MotoCycles®-- WE ARE ONLINE ONLY - NO PHONE CALLS MADE OR RECEIVED.

Advice needed on sick Stone please!

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

  1. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

    Joined:
    Jan 28, 2009
    Messages:
    58
    Likes Received:
    15
    Location:
    Guildford, England
    Hi Vagrant,

    You obviously saw the price €411.29 that a German supplier, Stein Dinse quoted for a genuine Moto Guzzi GU01530500 TPS. They are also good enough to quote for an alternative where it is available.
    In this case there is a Ducati unit, 28440021A available for €283.01.
    I will search around the web and see if I can find a better deal. I should have checked whether Todd can still supply suitable replacement units at sensible prices.
    I am reluctant to spend that sort of money without some confidence that it will fix the problem.
    My existing unit sets up as it is supposed to using a voltmeter and I don't understand how it can affect only the R//H cylinder.
    What were the symptoms of your failed units?
    As you may have read, my obliging neighbour has a crashed EV that he has allowed me to take any parts from for testing etc. I already have the R/H throttle body and could easily swap the L/H to go with it!
     
  2. vagrant

    vagrant High Miler GT Contributor

    Joined:
    Aug 2, 2009
    Messages:
    875
    Likes Received:
    386
    Location:
    Gainesville, Ga. or Green Valley Az.
    Just swap the tps. First one would lose cylinder when very hot and muggy. Second might not start after stopping for gas when hot. I think it might have been sticking in a open throttle position. Third was goofy throttle response. If a drop of gasgets in there and evaporates it gums them up. Also a high wear item.
     
    Gwilliam likes this.
  3. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

    Joined:
    Jan 28, 2009
    Messages:
    58
    Likes Received:
    15
    Location:
    Guildford, England
    Thanks for that!
    I'm past trying to understand the whys and wherefores and I've already invested so much time in this that changing the TPS is no big deal.
    It sounds like at least one of yours affected only one cylinder, which appears similar to mine. I have up until now assumed that the single TPS must send the same signal to both injectors so couldn't understand how only one cylinder could be affected.
    I will try my neighbour's spare unit tomorrow and if - God willing - it fixes the bloody thing, I will pick up a new one and fit that.
    You were quite right, after a bit of research I found a Guzzi specialist that has a couple of new ones for about £90.00 each.
     
    john zibell likes this.
  4. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

    Joined:
    Jan 28, 2009
    Messages:
    58
    Likes Received:
    15
    Location:
    Guildford, England
    Hi guys,

    Well don't ask me to explain the logic behind it but Vagrant nailed it!
    I swapped the complete L/H throttle body from the donor bike this morning and it is back to running properly on both cylinders.
    I have therefore confidently ordered a new throttle position sensor which I will fit to my throttle body before refitting my overhauled injector to my R/H body and fitting the pair back on the bike.

    It does demonstrate what a valuable resource this forum provides. It made no sense to me that the single TPS could affect one cylinder independently of the other.
    After days of head scratching and swapping bits around, based on what I considered a logical process, I had to concede defeat and rely on Vagrant's previous experience.
    You can't learn that from the workshop manual!

    Thanks too, to John for keeping me going with suggestions that on one or two occasions stopped me from putting a match to the bloody thing!

    Have a good weekend!
     
    Wildroamer and john zibell like this.
  5. vagrant

    vagrant High Miler GT Contributor

    Joined:
    Aug 2, 2009
    Messages:
    875
    Likes Received:
    386
    Location:
    Gainesville, Ga. or Green Valley Az.
    Glad it worked. You are not alone. 90% refuse to believe it could be a Tps until they spend tons of time chasing what makes normal sense. It's a Guzzi after all.
    I made the same mistake the first time. Wasted a year because that one only acted up in 85+ degree weather with high humidity.
     
    Gwilliam and john zibell like this.
  6. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

    Joined:
    Jan 28, 2009
    Messages:
    58
    Likes Received:
    15
    Location:
    Guildford, England
    Hi guys,
    As a follow up to the throttle position sensor replacement: all of the original parts have now been refitted with a new aftermarket tps.
    I set that up using John's preferred method of setting the 150mv with the L/H butterfly fully closed and the linkage disconnected, before winding up the L/H idle stop screw to achieve 520mv.
    I then reconnected the throttle linkage and started the engine to sync the two throttle bodies. The engine ran on both cylinders and the carb sticks behaved fairly well but the air bleed screws were not achieving a good balance so I wound up the R/H idle stop screw to balance it. That worked well and I adjusted the sync linkage to provide a balance above idle on the sticks.

    When I test rode the bike all was well but I noticed a new noise as I start to accelerate. It is difficult to describe - I initially thought maybe it was an air leak after refitting the R/H injector as it was a pulsing type squeaking noise.
    I have since experimented and found that it is not apparent at idle but comes in as the revs start to build beyond 2000 as you are climbing through the gears.
    It appears that you drive through it as you back off the throttle, although it returns as you accelerate from a cruise.
    I did recheck the throttle bodies and found that I had left both idle air screws wound fully in so out of interest I wound them both out a quarter turn. Road testing the bike showed this to be a mistake as the engine ran rougher at light throttle with coughing in the air filter and some popping in the exhaust, although the original noise was not apparent.
    I have now returned the screws to the fully closed positions and the bike is running smoother but the whistle/squeak noise is back on acceleration.
    Could this be detonation? (Pinging, pinking etc)
    I thought that an anti knock sensor was fitted on modern FI/ignition systems to monitor and adjust ignition timing to avoid this?
    Any ideas, suggestions or comments are welcome!
     
  7. V700Steve

    V700Steve High Miler GT di Razza Pura

    Joined:
    Dec 8, 2008
    Messages:
    920
    Likes Received:
    328
    Location:
    Atlanta area, GA
    For air bleed screws, I set these 1/2- 3/4 open then balance TB's at idle w/stop screws. I make the screws most exact with each other. This is me tuning, I do it w/all that have bleed screws. Other's may do it differently. The more you close the screws the richer the bike runs.
     
    Gwilliam likes this.
  8. vagrant

    vagrant High Miler GT Contributor

    Joined:
    Aug 2, 2009
    Messages:
    875
    Likes Received:
    386
    Location:
    Gainesville, Ga. or Green Valley Az.
    any chance the boots going into the airbox aren't seated.
     
    Gwilliam likes this.
  9. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

    Joined:
    Oct 28, 2008
    Messages:
    8,019
    Likes Received:
    856
    Location:
    Huntsville, AL
    My guess is if the air bleed screws have to be closed, the injectors aren't delivering the required fuel. See if you can run some BG44 through the system to see if fuel delivery improves. Here is a UK site for the product. bgprod.co.uk/products/fuel-and-air-intake/bg44k
     
    Gwilliam likes this.
  10. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

    Joined:
    Jan 28, 2009
    Messages:
    58
    Likes Received:
    15
    Location:
    Guildford, England
    Thanks for the suggestions.

    There is a possibility that at least one of the rubber elbows between the airbox and the plastic tube to the throttle body may not be fully engaged. I disturbed them several times swapping throttle bodies around so I will pull the tank and air filter to check and reseat as required.

    I did send one injector away for testing and was informed that there was no fault with it. This made sense as by then we had established that the problem was the TPS.
    There had been no problem with the air bleeds prior to this and the loan throttle body with injector also worked fine but it is simple enough to run some BG44 through the system, so I'll get on it.

    If all else fails I will try V700Steve's suggestion, although I feel that it should work with the factory settings and just needs a little tweaking to clear faults that I may have introduced.

    I will have a play and get back to you all with the results.
    Thanks again!
     
  11. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

    Joined:
    Jan 28, 2009
    Messages:
    58
    Likes Received:
    15
    Location:
    Guildford, England
    Hi Guys,
    This is just a short update on the progress so far:
    Vagrant was correct with his suggestion that the air outlet pipe elbow to the L/H throttle body wasn't completely seated in the air box.
    Unfortunately, correcting the fault made no difference to the squeaking/ticking (possibly detonation pinking) noise apparent at around 3000rpm as I load the engine.
    The noise switches on and off as I open and close the throttle in third or fourth, thereby loading the engine.
    If I gently increase the speed up though the gears, minimising the load applied, I can avoid the noise.

    On the Bosch electronic FI/ignition system there is an anti knock sensor that adjusts the ignition timing hundreds of time per second, retarding it just enough to avoid detonation. Does the Magneti Marelli system incorporate the same arrangement?

    I am still waiting for the BG44K fuel system cleaner that I ordered. Once that arrives I will run that through with a couple of tankfulls of high octane petrol and report back!
     
  12. vagrant

    vagrant High Miler GT Contributor

    Joined:
    Aug 2, 2009
    Messages:
    875
    Likes Received:
    386
    Location:
    Gainesville, Ga. or Green Valley Az.
    "Unfortunately, correcting the fault made no difference to the squeaking/ticking (possibly detonation pinking) noise apparent at around 3000rpm as I load the engine."

    And there is your problem! it's a Guzzi, not a Harley. big bore and a short-stroke. no Guzzi ever made to date needs to be run under 3500 and most especially yours needs 4000 RPM and hot weather and poor gas compounds the issue.
     
    Bill Hagan and Gwilliam like this.
  13. V700Steve

    V700Steve High Miler GT di Razza Pura

    Joined:
    Dec 8, 2008
    Messages:
    920
    Likes Received:
    328
    Location:
    Atlanta area, GA
    Don't forget to clean the bypass airscrew passage, I've seen them full of goo many times.
    There is no anti-knock sensor.
    There is a idle mix adjustment if you have software
    Bypass screws take care of idle & off idle up to around 2200rpm

    Todd has software for sale in the store. If you have open exhaust you may need more fuel. Todd can also fix this.
     
    Last edited: Jul 19, 2020
    Gwilliam likes this.
  14. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

    Joined:
    Jan 28, 2009
    Messages:
    58
    Likes Received:
    15
    Location:
    Guildford, England
    I have a Power Commander III USB with the map appropriate to the H pipe, Lafranconi Riservato Competitzioni mufflers, K&N air filter element and cut down airbox lid.
    I have been running it quite happily like that for several years but something has changed slightly since messing with the throttle bodies etc in the process of fixing the TPS fault.
    Do the bypass screw air passages just require a good squirt of carb cleaner and a blast from an airline once the screws are removed? It is tempting to do it in situ as I'm getting fed up with removing and refitting the throttle bodies!

    I have disconnected the Power Commander temporarily to see what the different, original fuel map does. I may also try richening up the fuel around the 3000 rpm range but I'll leave that until I've tried the higher octane fuel etc.
    The bike is now quite rideable but it is different than before I started and I would like to know why.

    I understand and respect what Vagrant is saying about the oversquare engine being more revvy than torquey but it used to be quite comfortable being ridden through the 3000 rpm zone and now it sounds to me like it is detonating.
     
  15. V700Steve

    V700Steve High Miler GT di Razza Pura

    Joined:
    Dec 8, 2008
    Messages:
    920
    Likes Received:
    328
    Location:
    Atlanta area, GA
    Just a shot of carb cleaner. If you got pinging w/open exhaust and no extra fueling like the PC3 than it is normal to hear it.
    It should be like you describe when under load and short on fuel.
    The motor is going to be different cause you changed the TPS and the baseline set. Unless the old one was at the same place.
    Once you get it synced plug in the PC and see if your pinging goes away, it should, depending on the tune in PC.
     
    Last edited: Jul 19, 2020
  16. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

    Joined:
    Jan 28, 2009
    Messages:
    58
    Likes Received:
    15
    Location:
    Guildford, England
    That makes sense but I have recently learned that making sense does not necessarily apply with Guzzi engines!

    However, I was checking the recommended fuelling map that I downloaded for a similar state of tune to mine and there are some big swings at 40% throttle, from -7% at 2500rpm to +9% at 3000rpm. It then goes back to 0 at 3500 before pushing back up to +10% at 4000rpm and +19% at 4500rpm.
    The need for extra fuel at 3000rpm is evident at 20, 40 and 60% throttle openings, whereas the map indicates a surplus at 2500rpm and therefore reduces it.

    As I have just fitted a new aftermarket TPS unit, it may be that your suggestion of a slight variation in the baseline, could be applying these fueling changes at a slightly different point of the rev range.
    The "pinging" certainly appears between 2500 and 3000rpm at around 40% throttle, when the map indicates the leanest mixture.

    Fortunately, it is a simple matter to either adjust the fuelling values at those specific points in the table or even, using the buttons on the PC, to richen the entire mid range by a few per cent and see what happens!
     
    Last edited: Jul 20, 2020
  17. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

    Joined:
    Jan 28, 2009
    Messages:
    58
    Likes Received:
    15
    Location:
    Guildford, England
    Having done a lot of further reading on the subject of throttle position sensor failures on Californias, my mental fog is finally clearing and things are beginning to make sense.
    I now believe that the problem is my use of a Cycleworks replacement TPS, which probably does not exactly match the output values of the original PF3C Magneti Marelli component. This is what is now causing the fuelling problems that are responsible for the detonation issues around 3000rpm.
    Having done so much swapping of components including another Magneti Marelli TPS as part of the L/H throttle body, I lost track of when the problem appeared. After finally identifying the failed TPS, I refitted my original throttle bodies with the overhauled R/H injector and new Cycleworks TPS, making the necessary setup adjustments and synching the throttle bodies.
    Somebody earlier in the thread had said "do one thing at a time, so that you can see what is making a difference." I should have paid more attention!

    I thought that the new TPS had fixed the original problem, so started looking elsewhere for the cause of the "pinging." I should have realised that it only started when I swapped the new Cycleworks TPS for the PF3C Magneti Marelli unit loaned from the donor bike!

    From my reading it appears that many people have experienced problems after using the PF4C Harley version TPS which does fit but again has a different set of readings programmed into it to suit the lower reving Harley engine.

    I will run the BG44K through the fuel supply as it arrived today and certainly won't hurt but I think a few tweaks on the Power Commander map should now resolve the final running issues.

    Thanks again for everybody's help and support.
     
    Last edited: Jul 21, 2020
  18. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

    Joined:
    Oct 28, 2008
    Messages:
    8,019
    Likes Received:
    856
    Location:
    Huntsville, AL
    Gwilliam, I have put the Harley PR4C on several bikes with no issues including my own bikes. If there is a problem, it is elsewhere. The difference in the curve between the two TPS types from Marelli is very little. The PF3C chart (PDF file) can be found on MPH web site. They did an excellent job comparing voltage to degree reading. mphcycles.com/the-pdf-mike-sent-that-i-dont-know-what-its-about-write-a-real-title/
     
    Gwilliam likes this.
  19. GT-Rx®

    GT-Rx® Administrator Staff Member GT di Razza Pura

    Joined:
    Jul 1, 2009
    Messages:
    11,413
    Likes Received:
    3,493
    Location:
    Malibu
    John, my good friend Jeff Brannen did that write up for GuzziTech. Mike sent him a MG TPS for comparo, so the data lives here on the Archive site. I've created an image file below to live here.

    MGTPSvsHDTPS.jpg
     
    john zibell and Gwilliam like this.
  20. Gwilliam

    Gwilliam Tuned and Synch'ed GT Contributor

    Joined:
    Jan 28, 2009
    Messages:
    58
    Likes Received:
    15
    Location:
    Guildford, England
    Hi John,
    You may well be right about the different Marelli units being pretty much the same. Installing the borrowed PF3C Marelli unit on my bike did not create the detonation problem. I believe that has only occurred since fitting the Cycleworks unit.
    They do supply a spec sheet with the new unit which I have photographed and will attempt to attach to this post. It doesn't really allow you to compare it with an original Marelli unit as far as I can tell, but you may know differently.
    Also, do you know if there is any significance in the numbers on the Marelli cases? Mine is marked as PF3C/00-1221BE but I have seen others bearing different numbers. Are all PF3C units the same and OK to use?

    I hope to use the Power Commander to just richen the small section of the table where the pinging exists.
    After Todd has produced a specific table that up until now has worked very well I don't really want to mess with it any more than is necessary. I would like to understand the problem rather than poking about in the dark.
    I suspect that if I refit the Marelli tps off the donor bike the problem will disappear.
     

    Attached Files:

    Last edited: Jul 21, 2020

Share This Page