2010 FLHTC - Cold Start - Tach sweeps between 750 and 1600. At the lowest it almost stalls and sometimes does. At operating temp it moves up and down maybe 50/100RPMs. Trying to take off from a stop; The best way I can describe it is if it had a carb I would be rebuilding and adjusting the pump.
I have replaced the plugs, wires, coils and MAP sensor with no improvement.
I have a V&H FP3, but put it on to try and fix the problem. Again, no improvement. Stage I air and slip-ons but otherwise mechanically stock.
Sold my 2000 FLHTC after 15 years and bought this bike, now having serious regerts. The bike had a lifter that took a few seconds to pump up so I put in S&S lifters, S&S High Flow cam plate, high flow oil pump, inner cam bearings, Fueling tensioners and adjustable push rods. The problem existed before I did this and still there. Any suggestions would be appreciated.

 

have you checked it out for a vacum leak,,,,maybe intake seals?
m

 

Forgot to post - I had already checked Intake and Exhaust for leaks, All good. Checked Fuel Pump pressure, Good Pressure. Changed Fuel Filter.
Owned and ridden Harleys for 58 years. First bike was a 57 Hummer. This is first EFI bike and also first TBW.
I noticed when I was riding today that I twist the throttle a little ways before I get any response; not much, maybe just under a quarter inch. I reused the twist grip sensor when I put on the mini apes. I know on the first TBW's they recommended replacing it but the local dealer said I was OK on the '10 model year.

 

i assume no codes thrown.
for idle issues especially cold i would look at a bad or miss placed temperature sensor since it tells the engine to richen up the mix. then i would look at the idle control for sticking. does yours have the cruise?? if so, there are two sets of sensors in the grip and they must play nice together. if the throttle sensor is not right then the throttle actuator will not be right, they act like a wheatstone bridge. the ecu also looks at it to tell if you are in no demand so idle will take over and also speedo input to chop fuel for coast down. a scan tool will probably be needed to look at input/output.

 

Have you cleaned the IAC?

 

If I'm reading things correctly the 2010 FLHTC doesn't have an IAC. It has a MAP/TMAP sensor and that has been replaced. If I'm wrong someone please correct me but it doesn't show in my parts manual.

 

Wow, wheatstone bridge. Haven't thought of one of them since my cable splicing days 50 years ago. Some people think that the twist grip sensor is redundant so if one side fails you are still good to go. You are right, they must send the same data. From what I have read and a recent experience, if they send conflicting data, the bike goes in to limp mode. I had the dealership change the throttle body connections out to stainless. Think it should have been a recall issue, but who am I to think.
Since you seem to be up on the subject, what was it about the early twist grip sensor that they couldn't be reused? Also, I didn't change mine when I swapped out the bars. Think that could be the problem?