I have been having sporadic issues with high idle when I come to a stop. The idle would be very high, the drop to a normal level in about 10~15 seconds. Today it was much worse than usual, and I finally got a check engine light!

Thanks to the forum search I found out how to retrieve the code, and what the code was for.

P0505 – Loss of Idle Speed Control
pn 22718-07A

It’s too early to call the dealer, and I don’t have my service manual with me, so I’m asking you guys.
What the heck does that mean?
Has this happened to any of you before?

 

P0505 Loss of Idle Sped Control EFI
Summarized from 07 Sporty Electrical Diagnostic Manual:

P0505 - Loss of idle speed control

Loss of idle speed control will result if the idle RPM is +-200 from present idle speed and IAC motor is at zero or maximum for greater than 5 seconds.

- Loss of idle speed control doesn't necessarily mean that the IAC is bad. There are other causes such as intake leaks, misfiring cylinder.

- Leaking injectors can cause poor idle. To check for leaky injectors remove A/C. Then with throttle wide open, turn key to ON for 2 seconds and then off for 2 seconds five consecutive times. Replace injectors if there is any evidence of raw fuel in the bores.

- Vacuum leaks - check for leaks

- Contaminated fuel

- Excessive Oil in crankcase

- TP sensor reading greater than 1 % (cable misadjusted), battery less then 9 Volts, or vehicle speed sensor (VSS) greater than 0 will disable idle speed control.

- Loss of battery power to terminal 31 of ECM.

The speedometer signal is an extremely important input for the Delphi fuel
injection system. The ECM monitors throttle position and speed signal inputs in
order to properly maintain the set idle speed. If the ECM loses the speed signal
for any reason while the throttle is closed, the ECM assumes the vehicle is
stopped and will adjust the idle air control counts to bring engine rpm to the set
idle speed. This could set a P0505 code and adversely affect engine idle.

*make sure you battery terminals are all tight cause that could result in drop in voltage
(got this from a google search)

 

Take apart and dielectric grease all connections,relays and fuses

 

Thanks JRK5892 , there’s a lot of good info in your post. I think the code was kicked because of “the idle RPM is +-200 from present idle speed and IAC motor is at zero or maximum for greater than 5 seconds”. As for what’s causing it, well tats still a mystery.

I just got off the phone with a HD tech, who said he has a sporty with the same setup. SE pipes, K&N filter, and the HD download. Apparently he had the same intermittent high idle problem until after the 10K service.

I have about 5.5K on it now, and this problem only started after my 1K service. Since adjusting all the cables is part of the 1K and 10K service, I think it’s most likely the “TP sensor reading greater than 1 % (cable misadjusted)”. I’ll double check this tonight.

FastHoss, greasing all the connectors sounds like a good idea. That could eliminate any voltage drops or intermittent signal loss.

Thanks for the feedback!

 

I know this is from a long time ago, but was this issue ever fixed?