Cleaning IAC

Discussion in 'Engine, Fuel and Exhaust' started by One For The Road, Aug 13, 2020.

  1. Hi all,

    I clean the Idle Air Control (IAC) on my 2005 Ultra when it starts to idle too low. Cleaning it usually helps restore the idle rpm to 900 or so. I did this last week and I had a tough time getting it started. It took several attempts to finally get it to start. Once started it ran okay.

    When I clean it I put a rag in the intake to catch the solvent (I use carb and choke cleaner). It always seemed to start hard after cleaning but this time it was exceptionally difficult to start. The only difference between now and before is this time the bike sat overnight before starting.

    My question is why does it start hard after cleaning the IAC. Is there a better cleaner to use.


  2. Roadking-1960

    Roadking-1960 Active Member

    Maybe after 15 years of use , it is worn out. I have often heard these IAC , go bad in time.
    I believe this part goes for around $50, , according to Ronnies HD.
    But if its running and starting fine , at this moment , why bother !. regards.
  3. joel

    joel Senior Member

    If you don't have any problem starting after the first start up after the cleaning, it most likely is do to the cleaner left behind that got past the rag.
    I always have this extended crank time and poor running after cleaning Throttle bodies, the cleaner act like a flooded condition and after the initial restart it returns to normal. What ever that .
  4. Breeze380

    Breeze380 Member

    I use throttle body cleaner, it is designed for fuel injection systems that have plastic parts. Carb/choke cleaner has chemicals that may be harmful to plastics. Maybe it is swelling your IAC pintle?? I also stuff a white rag behind the butterfly, mostly so I can see how much stuff got flushed. Do you cycle your ignition while cleaning? I do a couple of times, just to be sure cleaner goes thru while in different positions.
  5. Hi all,

    I will get some throttle body cleaner. I haven't cycled the ignition ... I just direct the spray into the IAC hole with the ignition off. Should I spray some with the ignition off them turn it on and spray again ... and do this a few times. I have just put a rag up against the closed butterfly but will open the butterfly and put the rag a bit further in the next time I clean it.


  6. Breeze380

    Breeze380 Member

    Yes, just cycle ign. while spraying, or when off then again when on. Not critical. If you lock the butterfly open, you will see the spray returning just behind the hole at the 12:00 position. As I haven't done it in a few years, I think (??) I remember the pintle tip being visible around the 9:00 position? I rerouted my head vents to atmosphere instead of to the air filter and don't have a problem with the IAC getting gunked up any more.
  7. Hi all,

    Thanks for all the replies. I have read where people have rerouted the head breather lines. I will look into doing that.

  8. Jeff Klarich

    Jeff Klarich Experienced Member Contributor