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Fuel Injection

Discussion in 'Motorcycle Tech Talk' started by tom_9132, Jul 8, 2005.

  1. tom_9132

    tom_9132 New Member

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    I have a 2002 Ultra Classic that will not idle consistently without opening throttle. At speed it runs fine. Is there some sensor that controls idle?
    Thanks for any help!!
  2. CD

    CD Guest

    TPS (Throttle Position Sensor) might be off

    Intake leak is very likely>>> I would start with that. Easy to check for a leak. At idle warmed up, lightly spray WD40 on the intake flanges from the left side. An increase in idle speed will tell you that there is a leak. I no one has changed seals since new, I would fully expect a leaky intake.


    The Manifold Absolute Pressure sensor (MAP) might be bad
    Delphi uses the ECU to control idle but, if someone messes with the throttle stop screw....
  3. TexasTripod

    TexasTripod New Member

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    A recent service bulletin recommended a re-flash, for no charge, to address rough idle on some models. I seem to recall that the 2002 model was included. Check with your dealer for that service bulletin. Many dealers have not heard of it, but I have seen it.

    TexasTripod
  4. TexasTripod

    TexasTripod New Member

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  5. Killer-B

    Killer-B New Member

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    Re-Flash

    Yes sir, I know of a few folks that have gone down to the local-stealer for the re-flash, seems to be the thing to do, even if your bike is'nt running bad. Of course check for the intake leak too. ;)
  6. Seahag

    Seahag New Member

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    Another problem I've heard of that can affect this is not waiting for your bike to go through its system checks before starting it.

    This was a reply from an EFI tuning professional concerning a similar problem...

    "Most times with what you are describing is caused by the IAC (Idle Air Control) being out of whack. It is not uncommon for this to happen just from starting the bike too quickly. EFI needs to have fuel prime and IAC set itself BEFORE you hit the start button. The IAC needs to get into position completely, and sometimes if you start the engine prematurely, the starting point will be read incorrectly and all other positions for the IAC for all throttle and RPM ranges will be off. This will also happen if you do a rolling start after a stall. It also screws up the interaction with the TPS (Throttle Position Sensor). The next time you start it, just wait a few seconds and then hit the button, you will probably be OK. If not, unplug the ECU for a few seconds, plug it back in and cycle the on off switch, being sure to leave it on for at least 5 seconds before shutting it off. If this doesn't work, it is probably the ECU that may be failing, or a bad IAC or TPS starting to fail."

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