High Idle On 2011 T-Bird Storm

[SparkyMan]

Hi. After removing throttle bodies, adjusting TPS and stepper motor (aka Idle Control), and reinstalling TBs, I find that after coming to a stop, the bike idles at around 1150 rpm yet, after about 15-20 seconds, it settles down to an appropriate 850 rpm.
Do I need to readjust, or is this simply a behavior of the stepper motor? Has anyone noticed this with their fuel injected Thunderbird?
Just out of curiosity, has anyone noticed that exactly 30 seconds after turning off the ignition (after just turning it on without starting and then turning it off) that the stepper motor hums and actually moves? I’ve often heard it do this after arriving home (in my quiet garage) from a ride. Just wondering.
Thanks
-Sparky

 

[atomsplitter]

If you have TuneECU you can check your stepper motor voltage. Mine showed it was too high so I adjusted into band.

 

[SparkyMan]

I take it you didn’t need to remove Throttle Bodies, so presume your TPS was within spec. TuneECU first allows for setting the TPS, and then the stepper motor. So, with my TPS within spec, all I need to do is set the stepper motor voltage to the displayed value, right?
There’s also an adjustment of the clearance between the arm and cam of the stepper motor in the service manual, which confuses me because that clearance, and TuneECU stepper motor adjustment, are both done with the same nut. Should I just ignore the clearance-which is a PITA to do- and use TuneECU?
Thanks for your response.
-Sparky

 

[Vector]

I know what a stepper motor is but what is its function on a motorcycle?

 

[SparkyMan]

My take is that it’s an automatic choke. My ‘09 Bonneville, while fuel injected, has a knob like a choke to be used for cold starts. My Storm doesn’t have a choke knob, but starts and immediately idles in the freezing cold. The stepper motor is also referred to as the ‘idle control valve’.
Vector, from your avatar I presume you have a Rocket, which likely has a stepper motor. If you’re interested, try turning the ignition on, then off, and listening 30 seconds later for the whirr of your stepper motor for what I presume is its closing the throttle. I’ve only recently discovered this behavior, and wonder whether it does it in warm weather, when a choke may not be required. I guess I’ll find that out in six months or so.
-Sparky

 

[sikatri]

Dreaded electronics. I hope y’all get it sorted. My only experience with a TPS of any kind on any vehicle was to buy a new one, install and hope it fixed the issue. LoL.

 

[atomsplitter]

First the stepper motor controls throttle opening at idle and when engine is cold. It's used primarily to ensure target idle speed is maintained and it also increases throttle opening when the engine is cold (basically a choke, more fuel less air).

That .5mm gap the manual states has to be made is the starting point when replacing a faulty stepper motor, and not the final stepper motor adjustment. TuneECU displays the stepper's voltage when it's out of band and you simply adjust the nut until it's in band. You can then run the stepper motor test function in the TuneECU program to ensure it's correct and you're done. You can watch the cam moving through the full stroke when you run that test. The manual says the reading will go from red to green on the dealer tool, TuneECU simply indicates the voltage.

 

[SparkyMan]

Thanks Atomsplitter. That helps!

 

[SparkyMan]

Any thoughts on whether to adjust stepper on cold or fully warmed engine? It seems one or the other might make a difference.

 

[atomsplitter]

Any thoughts on whether to adjust stepper on cold or fully warmed engine? It seems one or the other might make a difference.

I did it on a cold engine, wasn't a problem. Since I replaced the airbox sensor I haven't checked it again, so I may do that this week just to verify all is still sweet.