Problem Idling

Discussion in 'Electrical' started by ProF, Aug 13, 2009.

  1. ProF

    ProF Junior Member

    508
    28
    1
    I don't know if this is an electrical, fi, or fuel problem, but here goes: (03 RG, 43000 miles, tfi set at 4433)

    After changing the cams to s&s 510s with a gear drive and riding the bike for a week with no issues, it all of a sudden has an intermittent idle problem. I'll start it, and it won't idle - it'll drop to zero and die. But not always. After "resting", or restarting with me holding the throttle open for a moment or two, it'll settle down and be fine until I turn it off. Then, it may or may not do it again. The other night I drove it home on the freeway for about 15 miles, and it never settled into an idle. It died at the traffic lights after the freeway unless I manually held the rpms up. So, it's a sumetimes thing.
    Also, it'll "try" to settle into a 1000 or so rpm by falling way down and then surging back up (on its own) to normal idle. Sometimes this works and it smooths out, and sometimes it doesn't and the bike dies.
    I talked to the indy who put in the cams, and he is baffled. He suggested that the tfi may be going bad. He doesn't have the programs to do diagnostics for computer problems on the bike.
    Oh, I forgot, no codes are being set.
    One thing, could this be a battery problem in terms of low voltage? It seems that the bike will start with about 12 or so volts on the meter, and if I let go of the throttle before the voltage comes up to 14, the bike will die. Once the voltage is around 14v, the idle becomes stable at around 1000rpm.
    Would the voltage be the problem, or is it that when the bike is around 1000rpm the voltage is around 14v, and one doesn't "cause" the other in the sense of being the problem? The battery is pretty old, but I've not had a problem with it before.

    Any suggestions short of "take it to the dealer" would be greatly appreciated. The dealer is truly my last resort.
    Thanks much.
     
  2. glider

    glider Veteran Member

    25,464
    108
    44
    First thing that comes to mind is the IAC (Idle air control) It's a stepper motor and can be damaged pretty easily. Have the mechanic take a look at it and see if it is working properly.

    Second is to test the charging system output. It sounds like it's a bit lazy. The gauges aren't all that accurate but can be used as a general idea of the voltage. Load test the battery too and if it is weak replace it being it idles normal once the voltage gets up there. Generally anything above 9-10 volts will run the electronics but there;'s always that exception.

    Testing The Charging System - Harley Davidson Community
     
  3. ProF

    ProF Junior Member

    508
    28
    1
    Thanks Glider, I'll check all these things out. First, I'm going to find where that motor is and see if I can't check it myself. If not, I'll run the bike in tomorrow. I'll post the results.
    Thanks again.
     
  4. ProF

    ProF Junior Member

    508
    28
    1
    I Googled idle air control, which brought up a post on another Harley site that addressed a similar problem.
    Without plagiarizing his work, that writer basically referred the reader to a small valve just inside the throttle body and in front of the throttle plate (The idle air control valve). He sprayed carb cleaner up in there with the little "straw" that comes with spray cans, and all kinds of black crud came out. He cleaned up, put the air cleaner back on, and all was well.
    I did the same...also had crud come out. Now, all seems well. The bike starts up and immediately settles into the proper idle.
    I'll be doing a lot of riding tomorrow, so we'll see if this really was the problem. But,...so far so good!

    Thanks for pointing me in the right direction, Glider.

    BTW, do you think it would be worth spraying some wd40 or silicon spray up there to lubricate the valve? Or just leave it alone?
     
    Last edited: Aug 13, 2009
  5. gs34

    gs34 Junior Member

    639
    28
    5
    ProF....Where's the pictures of this here little hole??? We gotta have pictures so EVERYBODY will know where to look!!
     
  6. glider

    glider Veteran Member

    25,464
    108
    44
    A bit of WD wouldn't hurt.
     
  7. ProF

    ProF Junior Member

    508
    28
    1
    Another day gone by, and I've tried all kinds of things to get the bike to stall out, and can't do it. It goes right back to 1000rpm and idles just fine. Cleaning that IAC seems to have completely solved the problem.

    I did go back in and spray some WD40 onto the IAC, but didn't really notice any difference. I thought it might cycle a little more quietly, but it seemed the same.

    In any case, the idling is fine now, and thanks again Glider for the clue to the problem and for the really fine writeup of the issue in the Tech Tips. Such an easy fix, yet if you don't know about it, it's easily an HD job at the HDD's.
     
  8. glider

    glider Veteran Member

    25,464
    108
    44
    That's why I'm here :D

    Glad it helped you out.
     
  9. HD-Enthusiast

    HD-Enthusiast Member

    53
    6
    0
    I have had to do this on my 07 twice in the last 30k miles or so...I use carb/throttle body cleaner...:rider
     
  10. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

    8,176
    98
    16