I have had an on and off problem with my fatboy sometimes stalling when you pull up to stop at an intersection after riding a bit. Again this is random doesn't happen every time and usually if I turn the ignition off and restart the bike and its fine for some time. I also occasionally have an issue where the idle goes way up when I start the bike for a second. I am outside my warranty period and thought I recall reading something here about a similar problem but could not find it during a search. If anyone has any thoughts on this could please let me know or direct me to the right info. thanks ahead of time.

 

Mine does same thing. I took it to the dealer twice, still no fix. They changed a battery ground wire and replaced a speed sensor. Next mod will be a PC III or equivalent. Hopefully that will take care of it. I really only notice it after high RPM and high temp. Never seems to be an issue in cooler weather.

 

Check your IAC (idle air controll) to make sure it is working and there is no pinched wires or corosion in the connection. The iac may not be working properly.

 

nhbouncer,

I see you got rid of you're Fatboy.... I hope you enjoy the 2011...

I have a 2008 aniv. fatboy, and I STILL have that same exact problem.

Did you ever find the cause???

Thanks in advance

Ed...

 

Hi, guys
I’m not the greatest expert but I think you guys got it right – it is either the Vehicle Speed Sensor or the Idle Control Motor.

To determine the proper position of the throttle at Idle the ECM needs stable Vehicle Speed signal. If the Speed Sensor has accumulated lots of metal shavings on its face then the signal is very unstable, you can see fluctuations on the Speedo; you can also see the needle moving when you are at a stop. This one is relatively easy to fix – pull the sensor out of the tranny, clean it; then replace the oil as well since it obviously has lots of shavings. Clean the magnetic plug as well.

The other probable cause is the ICM. If there is intermittent connection to the ICM the ECM loses control over it. Since the time between downshifts/upshifts is too short, and the engine dies too soon when you come to a stop, the ECM does not have enough time to try to regulate the idle and set a code if unsuccessful.

The reason why the problem goes away if you turn Ignition OFF and then ON and restart is that the ECM reverts to a default Idle Throttle Position. Then, of course, it will again try to optimize the Idle while you are running the vehicle, and because of the above problems it learns wrong idle position.

 

Idle pos sensor!!

 

May be, I'm not quite sure.
The TPS (Throttle Position Sensor) has very robust diagnostics and failure of the sensor would set a code (the guys above say no codes were set).
Also, if the TPS is failing it would not recover with Ignition cycling (it is just a resistive sensor, a pot). The guys say their vehicles run fine after Ignition was cycled OFF/ON.

On the other hand, ever since a virgin gave birth - anything is possible! )

 

Replace 2 of them and they never set a code and for 28 buck easy to eliminate a sensor from the mix.

 

Don't get me wrong, I believe you that after they replaced your TPS your bike run fine; then you replaced it again and it run fine again.

I'm just sceptical about the root cause. You see, those sensors don't fail that often as one may think. Reality is, out of 100,000 vehicles you may get only 5 to 10 failing sensors in an year. Chance of two defective sensors winding up on the same bike is less than winning the jackpot. Have you tried your luck in the lottery?

 

I did the work and both failers were due to water intrusion in the sensor either due to washing or my stupid *** ridding in the rain without the football cover on.