Misfire.

Discussion in 'Technical Help' started by bluey, Jan 17, 2016.

  1. I need some advice.

    When pulling away at small throttle I get a misfire/cough cough before it pulls as normal. We have tried loads of things now but now I am at a loss. A 749s.

    New main loom
    PC3 mapped to exhaust
    TPS manually set and reset with the ECU (CO still to do)
    New plugs
    Good battery
    New air filters
    New injectors
     
  2. Possibly a fault in the TPS itself? Have you checked the electrical operation over the entire movement of the unit?
     
  3. Ht leads ,coils ?
     
  4. Out of interest, how did you manually rest the TPS?
     
  5. I can see that numbers rise on Guzzidiag as you would expect between 1.3 - 85 %. Funny you should mention as I ordered a fiat TPS just in case.

    I'll find the link for TPS reset that I used.
     
  6. Did you replace the front stick-coil?

    These often suffer from weather...
     
  7. The garage did say they tried another coil. Perhaps I'll just get another and try it myself.
     
  8. A jolly good clean-up might just help
     
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  9. Has the balance been checked? If not, that is the first thing I would try, if it's out then it will need to be set up with reference to CO levels too.
     
  10. No, the balance has not been checked by me. I have vacuum gauges here but how the heck do you access the adjusters would the engine running considering everything is packed inside the airbox assembly?

    And lastly what size thread is it for the brass nipples on the inlet?
     
  11. M5 from memory, but take one of the blanking screws out of an inlet to check! Mind you don't drop the sealing washer.

    Balance screws are accessible without taking the airbox off.
     
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  12. They are definitely M5
     
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  13. Thanks.

    Are the balance screws behind that rubber bung on the left of the air box?
     
  14. I am going to attempt a throttle body balance. In the attached picture which screw/screws am I aiming for?

    2004_DUCATI_749S_V004192__Throttle_Bodies__id_244078_01.jpg
     
  15. Does it not say in the workshop manual?
     
  16. To be honest I have not checked after reading it is not part of the servicing procedure. I have found the info elsewhere now anyway and have posted a picture in the 749/999 forum.
     
  17. Nope!Just checked and I cannot see any ref to it at all.
     
  18. The balance linkage adjustment, locked off with yellow paint is set at the factory and should not be touched. The air bleed screws, slotted head recessed screws, are used to set the vacuum balance at idle but also to achieve the correct CO ratio.
     
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