I have a 2002 RoadKing and all of the sudden the idle has become low,like between 500 to 750 at best. I heard there is a idle adjustment that you can make?

 

The idle adjustment is on the carb'ed bike. Is this what you have or FI? There is an idle adjustment screw on the carb which is difficult to get to on the fly. If not already done, you need to drill out the brass plug and install the idle adjust. The plug is there for emissions purposes.

 

This is the FI bike.

 

I am having the same type of problem with my '03 wanting to shut off at stops due to low idle. Idle is fine at initial startup. Any suggestions on where to start?

 

i have adjusted the idle up on a road king when it didnt want to idle after warm up...it was fi ...i took the breather off,and operated the throttle,there is a little screw ,seems like it was maybe a torx,not really sure as most bikes i mess with are carbed...anyway,you should be able to see where the screw is by operating the throttle,

 

If it just started doing this and you haven't replaced hand grips or anything like that then first I would do the easy thing. On the right side remove the side cover and remove the 5 and 15 amp fuses, let it sit for about 15 - 30 minutes before plugging them back in. Once you have done that then turn the ignition switch on but don't start the bike, look and see that the IAC ( stepper motor) functions above the throttle body. Once it activates then shut ignition switch off and turn it back on and start bike. See if this helps before you start adjusted the screws. I know this works on MM FI, not sure if you do this to the Delphi?
Electra 1

 

Good tip Electra...

 

First try the tip from electra. Then check your throttle cable slack you can take up the slack at the cable adjusters under the throttle handle. If the cables are tight I would look at the IAC sensor & valve. Both of you have the Delphi system and will need the electrical diagnostics manual to troubleshoot.

The idle speed needs to be set with a HD digital technician or SERT if you have one. But the speed and warmup steps are programmed into your map and will not change unless the map is corrupted but the bike would run very poorly. You may want to look at your IAC (idle air control), IAT (intake air temp sensor) and your TP (throttle position sensor) and VSS (vehicle speed sensor). The data from the VSS is used by the ECM for idle speed control.

BTW, you need to correct this problem as idling below 950 RPM can cause dangerously low oil pressure in a TC88 and result in engine damage. Note: I am taking this information off my 2006 and your may be different.

 

If this happened all of a sudden don't change the throttle stop screw as it screws the relationship of the tps and ecm. Most likey it is an iac problem with the unit itself or the hole where it gets it's idle air from may be crudded up. Spray tb cleaner up into the hole first to clean it all up and see if it improves first before changing the iac. If it is running richer than normal at hot idle consider one of the other sensors not working correctly, like O2, IAT or Head temp.
Ron

 

I agree it is probably a sensor problem. With FI you must deal a little different that the old ways where you just adjusted things. You can still "think" the same way though. Instead of adjusting the buterfly open some more, think about what does the same thing with FI. The IAC .
The other thing that could affect this is the Crank Sensor but that would cause more problens I would thing. It is a Hall Effect sensor and might not be getting a good signal at low RPM. something to think about for later maybe.
Rababos is right and the IAG is easy to get to, and the first thing to check.