I hate to rub it in, but I love my Dyna as it is carbed as well. My softail is EFI which works great, but the carb is so much easier to work on. As far as your low idle issue, try cleaning the TPS off first as it can get vits of metal on it that can affect it's ability to function.

 

Chris if your going to go in there to check it man just replace the fuel hose and also pop a new filter in there while you have the pump out

 

i have a 3 days off this coming weekend so ill probably pull the tank guts out Friday night and if i see anything worth changing ill hit the dealer Saturday and most likely get a new tps and pick up some throttle body cleaner to spray out the Iac....

 

Bring it to the dealer ......

 

@OP did you figure out your issue yet?

 

Not yet. All I've done so far is r&r air filter and backing plate, spray MAF cleaner (visual inspection), and Sea Foam into the tank. Work's been busy last couple days and no time to work on the bike (or go to the dealer). Hoping I get some Sunday time this weekend.

 

just for clarification. IAC motors do not have "sensors."
The only way an IAC "knows" where it is, is when it resets. The reset drives the pintle into the seat and THEn backs out a calibratable amount of "counts."( then the "position of the pintle os known")
"Counts" to an IAC system are the number of turns + and - as the motor rotates position.(As the motor rotates the pintle is screwed in and out!)
When the IAC motors wear a little ( it can happen in even a few miles, as I had NEW development vehicles with "bad" IAC motors) that "slop", as the pintle drives in and out, causes the "known position" to become LOST.
Once "lost" the pintle may not correctly catch the RPM as the software attempts to control IDLE speed.


Counts can be added or subtracted as the "slop" in the IAC motor as a function of vibration of the motor. Also, IAC motors MOVE when the throttle is opned and closed! Called "throttle follower" the IAC motor is continually moving as a function of THROTTLE inputs, that helps control decel RPM and to some extent accel "feel" as a little extra airflow at low throlle openings! So the longer the "RUN CYCLE" (more time between key off reset), like HWY riding, the more chance the actual pintle position can be LOST when returning to IDLE!

Also for the IAC motor to properly control IDLE speed, that "throttle stop screw" is actually set to a known "shipping AIR RATE" Some Idle air is required to flow between the throttle body and blade. ( the reason if anyone wonders is the IAC system is not fast enough with enough resolution of air rate to prevent under and over shoot of the RPM control speed)
That is why "they" tell you to never touch the "idle stop screw", it is set to flow some air and that air is part of the IAC system control flow.
So besides "cleaning" an IAC motor (once a motor is worn enough to allow the "slop" to add and lose counts, they rarely work correctly again.
But what can happen is carbon and debris build up in the throttle body bore and reduce that"shipping air rate" I refered to above. Cleaning the throttle body bore can sometimes fix IAC control issues!!

Also where the TPS comes in, is the IAC motor "throttle follower" (counts added or subtracted during every throttle delta change, both plus and minus!) are dependant on TPS position. i.e. when the IAC software control not only commands how much to move the motor for each "%" of TPS, but the IAC software function between "throttle follwer" (simply adding and subtracting counts as the throttle moves) and IDLE CONTROL, (where the software attempts to command idle speed) is also a function of TPS!!
If you do not get an "aftermarket device" TPS zero set correctly, it can cause stalls and poor IAC control!

As an example if the "TPS" as read at the ECM is too high,( reading some percent of TPS open, when the TPS is really "on the stop") The control algorythm may not start to try and get control os IDLE before the RPM has dropped too far. And you get sags and stalls from an improper TPS input to the software!!!

I will add having calibrated IAC systems for many years!
I hate IAC motors and the guys that SELL them!!
We have gone around and around about how poorly IAC motors are designed. I will also add, this "lost counts" issue has been a soe spot in the auto industry for many years. ( And the same folks sell those SAME IAC motors to Harley!!!)
Drive by wire and Idle controlled by the throttle blade position vs. "IAC motor" is a large reason (although not the only reason) Drive By wire was invented!!!
I hope that helps to understand slighty how an IAC system functions!

 

FBRR Were did you get this?

"That is why "they" tell you to never touch the "idle stop screw", it is set to flow some air and that air is part of the IAC system control flow."


That is not my understanding. When the throttle plate is shut, it will just about stop water. At least on my 04 with it's open loop system. However I have always deduced this from two facts. One is in an adjust procedure I have for setting a throttle body up after overhaul and it is for a car, not a Harley. Also in my Harley Electrical Diagnostic that is one place were it describes what causes idle problems by idle air air going by improper adjusted throttle plate. I also know you can indeed trick it by using the throttle plate but you will get run-on (dieseling) when you turn it off.

Drive by wire eliminates one more mechanical cable but also helps greatly when the throttle is snapped shut in stopping to allow a measure amount of air to be still added to engine to burn the rich mixture left in intake at the instance the throttle snapped shut. The IAC did not have this ability.

Has it been your experience that one of the problems being caused to the IAC is people cleaning and washing crud up past seal into the IAC motor itself killing the sensor counter that the ECM reads? (Guess it should be called a resolver (see attachment)?)


Anyone out there with a JUNK IAC they can carefully cut apart and post some good pictures of the seal area up past pintle. To answer my own question I just grabbed a 2007 throttle body off an FLHT 27708-06 on e-bay complete with all sensors and injectors and all for $20. Will test the throttle plate and tear the IAC apart. Anyone know if the injectors will fit my 04? What is an FLHT (TC 96 Cruser?)

 

You have to have fuel for run on. With FI when you turn it off it shuts the injectors off so no fuel no runon. I have test this on cars. With the rpm at 2000 rpm and turn the key off. If you do have run on then you have a leaky injector.

 

"When the throttle plate is shut, it will just about stop water.!!!! But it WILL NOT stop water because of that small amount of "set air rate."

Where I "get that" is I have calibrated vehicles with IAC systems for many years. And every application has a standard "set point for shipping air rate"( that is the amount of leakage past the blade at "closed throttle")
Some of my friends (from Automotive) were also resident at Harley after they worked in automotive. While the "shiping air rate" is small!! There is a SET air rate at the throttle body.

That Air Rate is normally set as a function of Idle air.( Or more correctly it is set to be the equal of about 20 "counts" of IAC position.) The stop is not set AT ZERO air flow. And that is why even a little throttle body deposit build up can affect the IAC system function.
( And if you are wondering the "automotive" software function is nearly the same as Harley, calibration values are far different, but function and design is very similar!)

P.S.
I should add, some years ago the "IAC folks" did have the throttle stop screw set to ZERO Air flow. The "shipping air rate was then a function of a small hole drilled into the throttle blade to yeild a given amount of air!!! It was a horrendously BAD idea!! If you think about what I said with regards to small "throttle bore deposits!!" causing issues, imagine how much faster a small hole in the throttle blade becomes plugged from engine blow back deposits!!!
But the IAC system is not fast enough nor have enough "resolution" of Air flow vs. RPM, to function without some shipping air rate set at the throttle blade.