I have 1998 ultra.. I am having pretty frequent super high idle(3000 rpm).. bike is stock(70k miles)....did recently change intake gaskets( were definitely shot) thought that took care of but recently started again.. bike starts and runs good but after a little riding idle will not come down(dangerously high) does not do it all the time...resetting it with the on/off ignition switch trick usually works for getting me home safe..do not want to throw parts at it if I can avoid..as bad as the intake gaskets were I am thinking about changing all injector o rings etc ..not sure air leak would be able to cause such high idle

any help appreciated

 

I'm not really familiar with the fuel injection system but I'd be lookin at an air control valve or throttle position sensor.

 

It is probably the ISC (Idle Speed Control sensor, sometimes called IAC). Fairly simple fix, but make sure that you follow the instructions on recording the voltage from the TPS. You can do this by sticking a pin down connector at the grey/violet wire leading to the TPS and attach the (+) on the DVOM to that and (-) to ground. You may wish to read Harley Tech Bulletin M-1105 for more info.

 

You might also consider review of the engine temperature sensor buried in the center of the front cylinder jug.
That sensor when bad will cause runaway throttle, rapid fluctuation from high to low and make ridding very difficult.
Basically the bike gets confused switching from hot to cold to hot to cold rapidly and tries to adjust making riding very difficult.
The manual will show the various temperature=resistance numbers.
It is a thermo resistor so you can check it with a digital meter and some ice/heat off the bike.
The unit is specific for M & M fuel injection and cost about $100 for the part 32446-95.
Here is a link for a parts finder.
http://partsfinder.onlinemicrofiche.....asp?make=hdmc

 

This other link might help you to understand some M & M fuel injection diagnosis.

 

Thank you guys! will start doing some checking

 

FYI.... I unplugged idle control unit...quick 50 mile ride..bike runs good..figured at worst could eliminate or verify the TPS.. so far so good

 

Thank you for returning with information.
It really helps to get information back so others can learn how to resolve their problems.
Glad to know you are able to roll.
You will probably have to hold the throttle when bike is stone cold.
Let us know how you finish.

 

I ride a 97 Ultra I bought 2013. I rebuilt the motor last winter to eliminate the oil leaks and at the same time had the heads shaved..... and introduced a Cobra Fuel Management System. I was hoping the FMS would help with my idle issues.... Dealer said he thought it was running lean and low due to upgrades.... in the warm months (Canada). In cooler months, my idle has started racing. Starts great at cold idle setting.. drops to 950rpm as it is supposed to... until I start riding in the cool air. Then the idle increases... 1,800, 2000, 2600rpm..... I had the dealer reset the Idle Control settings... didn't change anything. Pulling the ECM fuse for 5 minutes sometimes works....

My buddy says get rid of the M&M EFI system. No carburator will do that.. old school.... and he is probably right, but having invested $700+ into the Cobra FMS, I was trying to avoid that.... btw, the FMS from Cobra doesn't affect idle, but certainly helps with power. in fact I had to back mine off a bit as it was throwing gas out the pipes....

End of tale, I believe the problem lies in the temperature sensor. When the computer believes the bike is cold, it increases the idle.... never happens in the heat.... at least that is where I am looking before I undertake the conversion to a carb.

 

One of the most common failures on the Early MM bikes is the engine temp sensor. This is exactly how a bad temp sensor causes idle issues and rich running issues.
change the temp sensor and all will be good again.
Bob