Idle Air Control (IAC)

[Jack Klarich]

Mr. Data you are so On Target with that statement. And it does not just apply to Dealerships. It is almost everywhere I go. Why can't people just say "I don't know the answer to that question" instead of giving me this lip service speech.

If I don't know the answer to a question, I just say "I don't know". What's the big deal in saying that.

Very well said Hoople, my customers like that answer, I wont lie or pretend to know if I dont:s

 

[scaraboy1]

Hi,
Xl 08 pop on decelerating.....
Have lost nut's on rear pipe and replaced new!!!
Good accelerating but Erratic running at middle power....IAC ?????
Any suggestions.

 

[Hoople]

but Erratic running at middle power....IAC ?????

Very Very Remote chance of the IAC doing that. Not saying it can't be but way down on the list. If even on the list.

Elaborate on the word "erratic"... Lean surge?, hard misfire?, can you power through it?, did it just start doing it after a mod?, piggy back tuner installed?, current mods to bike?,

 

[Breeze3at]

Hi,

Have lost nut's on rear pipe and replaced new!!!
Any suggestions.

What nuts on rear pipe? Header to head, header to muffler, muffler to mount?
If it was header to head, the pipe could have moved and gasket is not sealing when new nuts tightened.

 

[Jack Klarich]

What nuts on rear pipe? Header to head, header to muffler, muffler to mount?
If it was header to head, the pipe could have moved and gasket is not sealing when new nuts tightened.

I uses grade 8 with lock washers no more problems, and like Breeze said check or replace the gaskets cheap insurance and torque to 10 ft lbs:s

 

[nvsteve]

Hi,
Xl 08 pop on decelerating.....
Have lost nut's on rear pipe and replaced new!!!
Good accelerating but Erratic running at middle power....IAC ?????
Any suggestions.

08 and up are different than previous years. They use something different to control idle than an IAC, or it's in a different place. Either way, the IAC only affects idle speeds.

 

[TQuentin1]

OK. Back to the subject of the IAC. I have been having problems with mine over the past few months. Seems like I am having to clean it out with carb spray at least once per month. Below are the pix from today (would not hold idle and died immediately if the throttle was released).

Stripped off the A/C and put a bibb on the side of the engine/tranny to keep the spray run-off from soaking the side of them. Also stuffed a wad of paper towel against the butterfly to stop the liquid from pouring into the intake/cylinders.

You can see the port at the top of the intake through which the IAC works. The rod is all the way down (shut off) so the engine was NOT idling. I had to restart the bike and hold the throttle open while killing the ignition to allow it to stop with the rod retracted.

Sprayed in the port like crazy. Let it sit a bit and then repeated a few times. Little bits of black carbon like material washed from the port. After finishing all that, I started the engine (takes a bit to suck up all that carb sprayer over-run) with the throttle cracked about half way. Once it finishes exhausting all the carb spray, it ran and returned to idle as normal.

I think I will have to replace this IAC. Must be all gummed up inside to require cleaning this frequently.

TQ

 

[Jack Klarich]

TQ, I am wondering if checking the IAC like we checked EGR valves would work here.Hold the IAC upside down in your hand, put a few drops of oil on the pintle valve, if it disappears the valve is bad

 

[Tatanka]

Clicking noise around Trottle Body after bike is turned off. Happens about every 15 seconds. Buike runs fine, except when i turn it off, we hear that pulse noise every few seconds. took it to the harley shop and they said ECM. $600 with labor. I think they are just part changing because they dont know. They mentioned Idac or something sensor. Th is is a Fuel Injection. Any ideas out there be fore I drop $600.

 

[90FXRS]

I've always used mass airflow sensor cleaner to clean this little booger. This info I got from a friend who has worked for Harley for abot 25 years.