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07 FXST Idle

Started by Buglet, April 14, 2022, 12:30:09 PM

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Have a basic stock 07 FXST that about 30 % of the time when you come to a complete stop it's at a high idle, it takes about three to five seconds to come down to it's normal idle, other then that it runs good with no other problems. The IAC and TPS were change and no codes come up. What I'm missing. 


DO you have a way to log IAC steps?  It's a closed loop system and sounds like it is adjusting for intake leak.
Semper Fi


I was thinking the same, check for vacuum leaks.
We learn from history that we do not learn from history


  No intake leaks to be found. The last trip out about 15mi did it the first stop about one mile idle high for about four seconds, stop over a dozen times OK the last stop I know it was there as I was slowing to stop you could feel the high idle pulling you for about 1/4 mile until I came to a complete stop, five second later idle normal.


Look at your calibration.   Look right above where it idles in the VE table.  Are the numbers close?  Or is there something like 60 at 1000 but 45 at 1125?

Usually the 1125 cell gets filled in with transition during deceleration, and can be lean.  I like to map 1125 and 1250 with steady state by raising idle.  One of the last things I do during tuning. Both cells can be mapped during same collection run with idle target table.

I only see this with cable throttles. 
Semper Fi


  Going to try to schedule some time to get back on this later this week or next. It has the factory stage 1 download. I just got done with a another one that's being at multiple shops for the last three years, what a PIA trying to figure who done what. 

Jamie Long

Idle hang is extremely common on 2007 bikes, we've found the great majority of the time the IAC has abnormal wear, it does not fit the bore in the throttle body properly, or it sticks slightly. We've replaced dozens of IAC's over the years to resolve this issue. We've also needed to adjust the throttle stop screw in a few application as well. H-D Service bulletin TT410 covers this specific issue, there is a link here>>


What is your tps voltage at closed position.  06-07 also had issues with the idle screw coming loose.  It's a 5 point tamper proof.
Powerhouse Cycle & Dyno - Performance is our passion


you have an intake leak, get new seals for the exercise and make sure backing plate is on, bolted to heads and then do up throttle body bolts, follow manual


  Finally had time to do more testing. Here's what happens TPS volts 4.9 the IAC drops down to 2 steps. Check for air cannot find none. Took of the throttle body the seals look good and soft just like new ones. Everything in the throttle body looks good. I have to be missing something. Thanks for all your help.   



  My mistake it the TPS is .49


Are you doing throttle body clamps up with backing plate on and torqued?

It may take 2-3 goes to find the sweet spot, try Vaseline as well


  Got time to look at it again. Found the problem air leak. IAC shows close, looks close hold finger over port stalls. Throttle body port looks good replace the IAC after this first started. What I'm missing. The owner said it always ran good. The reason it came in was for a fuel pump as it was sitting while he was defending our country. It only has 14k and is clean for it's year. 


   All good now just did a 20 mi test drive, now the owner will be able to ride around the country he fought for.