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Another St4s Immoblizer Issue

Discussion in 'Sport Touring' started by mgrover, Dec 27, 2019.

  1. must be a huge relief that the main hurdle is beaten.
     
    • Agree Agree x 1
  2. well as long as shes not running on one cylinder yes :p the back the right exhaust is smokey, the left nothing
     
  3. There's a link pipe so one exhaust doesn't really mean much :upyeah:have to put your hand over to confirm if gas is getting to both pipes
     
  4. yeah i was checking the pipes and then got lazy, ive gotta shoot of in half an hour so if i start resetting the tps now ill never leave.
     
    • Like Like x 1
  5. If it wanted to rev like crazy, I would say it’s probably firing on both.
    A sticky throttle is often due to the grip fouling the bar end or the lever/switch assembly.
     
  6. It might not be just the cable that need lubed. Make sure the butterflies snap back with the cable removed. It sounds like it needs the whole throttle body / TPS reset procedure carried out. Refer to Brad Black's site. I'd make sure that the fast idle lever is working. There is an adjustment for it at the cable drum on the horizontal throttle body. It is fiddly to adjust but worth it. When the throttle bodies and TPS are set up correctly there will be a position of the fast idle lever that guarantees an instant start* with a cold engine every time.

    *edit - I missed this out
     
    #186 Derek, Jan 25, 2020
    Last edited: Jan 25, 2020
  7. i think itll have to be that, but probably a job for monday
     
  8. Interesting.
    I have found that leaving the throttle alone and using the fast idle lever gives excellent starting in a way that I can’t replicate by leaving the fast idle lever alone and using the throttle.
    My bike has a servo start feature and I find the best way of getting instant starting is to stab the start button and open the lever quite quickly until I reach the point at which the motor bursts into life and then leave it there to warm a little or reduce it a tad to control revs.
    Do the throttle and fast idle lever operate separately and differently? Or I am imagining the difference??
     
  9. Cold starting requires the correct air/fuel ratio for a cold engine. My ST4s would fire once but not catch if the fast idle wasn't used from cold. If the fast idle lever was at full travel it wouldn't fire at all but with the lever about 1/4-1/3 forward it would fire up instantly.
    The air bleeds on your bike may be further open with a slightly richer fuel trim giving the correct air/fuel ratio for a cold start and allowing enough air flow to maintain an idle. Although it works for you I'd suggest that the fuel trim and air bleeds are not at optimum settings but probably not far enough off to notice in normal use.
    I'd say if it works for you leave well alone.
     
    • Agree Agree x 1
  10. When that bike worked it used to start everytime with no issues tbf and no fast idle. The fast idle was more to warm up the bike faster and stablize its idle since it searched slightly at idle. Albeit it hasn't been started in sub zero weather
     
  11. Dumb question but anyone that's reset the tps. Do I need to remove the throttle body from the bike or is it possible to do it on the bike and have access to the vital bits
     
  12. #192 Chris, Feb 2, 2020
    Last edited: Feb 3, 2020
    • Agree Agree x 1
  13. As it's a 4s (desmoquattro) you might need this one :- http://www.bikeboy.org/ducati4vthrottleb.html
    Starting point would be to hook up JPDiag, make sure the throttle is closed all the way (no input from fast idle lever, etc) and check what the TPS is showing (423mV, 2.6° according to Brad's site). You also need to check that the linkage isn't holding the rear throttle open slightly, giving a false reading.
     
  14. Best to disconnect the linkage.
     
    • Agree Agree x 2
  15. anyone got a picture of the ecu connectors i need ot fondle since mines diff from the site?
     
  16. I think this might help.
    59M.jpg
    EDIT : Image corrected for Engine Pin32 connection
     
    #196 Derek, Feb 8, 2020
    Last edited: Feb 11, 2020
  17. that defo helps
     
  18. am guessing pin 3 and 32 is for me? red probe to 3, black probe to 32. then fondle the tps screw till its within the correct range? then fondle the idle screw till its the right degrees?
     
  19. I've just spotted that that diagram is wrong. Pin 32 is TPS +5V, the TPS ground is pin 29 black/violet wire).
    I've found it easier to backprobe the TPS connector. If you pull off the rubber boot you'll see that you can take the connector apart for access. I can't remember exactly off the top of my head but it's not difficult.
    Wherever you connect the meter it should be between the violet/black wire (sensor ground) and the orange wire (TPS output).
     
    • Useful Useful x 2
  20. Can you not start by using JPDiag to read the value directly from the ECU? Much easier than trying to hack into the wiring?
     
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