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IAC Disassembly

12K views 16 replies 8 participants last post by  Shurock 
#1 ·
I went to start the bike today and it would not start. Cranks over fine and if I open the throttle, it will try to run. As soon as I return the throttle to idle position, it dies. Last time I rode, I had no problems. The bike sits inside so moisture should not be the issue.
I suspected IAC motor. I pulled the air filter and cycled the ignition to observe pintle movement. I did not see any movement. I removed the IAC, after checking with the forum and the factory manuals. I did use a heat gun prior to removal of screws. After removing the IAC, I reconnected the connector and turned on the ignition. The IAC motor ran and the pintle was driven right off the motor.
Am I screwed? How can I ensure I reassemble the pintle with the motor correctly. I did not see anything in the manual about this.

Mike
 
#2 ·
I had this happen to me a couple years ago when I was tinkering & experimenting with one.

Place the threaded screw on and hold in in place as the you cycle the run switch, it will go through an extension & contraction cycle, do it a couple of times (make sure to hold it & resist letting it unscrew all the way).

Eventually it will settle into place to its approximate resting position. You can try forcing it to seat deeper by pushing on the pintle and the motor will spin down.

Once you have it fully seated into the motor housing, reassemble onto the TB.

Then cycle the run switch and you should see normal movement.
 
#5 ·
So if I read this thread correctly there was an IAC malfunctioning, when looked at in the open it sprang apart, then instead of replacing with a new IAC it was simply 'reset' when reassembled and was able to go back into service? If I try to reassemble mine, it should stay together when I try to lightly pull the pin out and if it comes out easily it means the threads are stripped and IAC needs replacing???
 
#6 ·
........when I try to lightly pull the pin out and if it comes out easily it means the threads are stripped and IAC needs replacing???

What we experienced was a generally functional unit that at worst was sticking a little, in the process of removing it to clean it I inadvertently caused it to unscrew by operating out side of the housing, OP did the same.


Sounds like you have a damaged unit, replace it! :deal:
 
#7 ·
I think my IAC is okay... after getting it back together it does NOT just pull out so the threads are not stripped... it does function properly when I cycle the key, it only unscrews itself when I cycle the key while IAC is out of it's TB housing, when it's where it belongs it moves out then in with the key cycle.... am I 'good to go'? or is the IAC still defective as even though it moves it isn't moving in or out enough to allow the engine to idle properly? one way I can check (free too) is button her back up and run her, right?

I guess I'm now asking how precise is the IAC? does proper in/out movement suggest it's working properly or is there more to it?
 
#8 · (Edited)
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I guess I'm now asking how precise is the IAC? does proper in/out movement suggest it's working properly or is there more to it?
Maybe, but there are a few other things that need to be checked.

ECM idle control is a "hunting" action. If idle is not at the target idle speed (varies with measured coolant temperature dropping to 1200 or 1250 when warmed up), the ECM sends a signal to the IAC motor to either open a step (if idle is too low) or close a step (is idle is too high). The result is a constantly moving idle pintle with a constantly changing idle RPM, cycling slightly above and below (±200) the target idle speed.

If something is wrong (spark plugs, coils, air leaks, bad injectors, bad IAC motor, etc.) idle control will fail with the idle too high and the pintle fully closed or the idle too low and the pintle fully open. If this occurs the ECM will set a P0505 DTC = loss of idle speed control.

IOW, if you don't see a P0505 DTC then the IAC is working OK. If you do see a P0505 DTC then you need to check the bolded things above.

Another thing to note: the IAC motor only functions (and DTC P0505 is only relevant) when the throttle plates are closed (TPS < 1%), the VSS = 0 (bike not moving), and battery voltage ≥ 9 V.
 
#17 ·
Thank you for all your help. Wanted to give you an update. I switched out the IAC. It purrs like a kitten now. No problems yet. The idle is right on. I ordered a gasket to go under the airbox because the old one was deteriorating. When that comes in I’m going to do a cleaning of that whole area when I put it on.
 
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