Sprint ST Idle problem, surges and stalls

[Tuxlives]

Replaced Spark Plug, oil and Air Filter, now Idle Surging and stalls.

When I first put everything back together it idles ok, but slowly drifts slower and slower until it stalls.

If I ride it around it sits at slightly higher RPM than I'd expect. If I turn off the bike and re-start it right away the idle is very surge-y

Engine management light is on.

I think the airbox is on and down tightly, but am not super mechanically minded. Help is appreciated.

[ShervinRRR]

If the engine management light is on, there should be a fault code stored in the computer.

Many uses an industry-standard OBD-II interface.

Do you have an OBD reader?  (If not, go to eBay and buy one.  You can likely use it with your car, too.)

[trotsky]

If the engine management light is on, there should be a fault code stored in the computer.

Many uses an industry-standard OBD-II interface.

Do you have an OBD reader?  (If not, go to eBay and buy one.  You can likely use it with your car, too.)

Most auto repair stores will lend you one if you let them hold your license. Just park the bike outside, run in and get their OBD reader and see what the code says. Give it back, get your license and you are out of there at no cost.

[stk0308]

Are all the sensors plugged back in?  I'd start with the airbox.  Looks like there should be at least 2 sensors on it.  

If the MIL light is a temporary situation, it will clear after 3 heat cycles(cold, to working, and back to near cold is one cycle) of the motor.  You can cause a temporary error during maintenance.

You could try to let it self adjust.  Start it without throttle, let idle until the fan kicks in, then shuts off.  It will adjust it's own trim just a bit.  

But ultimately it sounds like your going to need to balance the throttle bodies and insure what the MIL light is saying.  I'm guessing your not hot to go to a dealer so you can do much of this yourself, with a cable, and some free software at http://www.tuneecu.com/

[stk0308]

Some light reading for Triumph FI bikes  
http://www.triumphrat.net/ecm-and-fi-tuning-help-tips-and-tricks/

[TheRedOnesAreFaster]

  
You can cause a temporary error during maintenance.

+1.

Very easy to do.  I started mine up after servicing it, and I did not plug in one of the hoses from the reed valves.  Instant engine fault.  Went away after I plugged it in the three heat cycles.

I would get the throttle bodies balanced, and check your air filter.

I know Sprint has a tenedency to totally trash the air filter and, in cold weather, it tends to idle way too high.