High Idle and P0505 code after IAC replacement

Hello fellow Tacoma lovers, I was told after a diagnostic that my IAC valve was absolutely non responsive and I would need to replace it, along with a leaky PCV valve. I ponied up and got an OEM IAC, IAC rubber gasket, throttle body gasket, and a PCV valve and grommet. It still idles high and threw a P0505 code.

 

Take it back, they either screwed up the diagnostic, or the repair.
P0505 is an "Idle Control System Malfunction"

 

Thanks for the reply. I actually did all the work. One shop told me they need to do an IRP, idle relearn procedure, but I asked the dealership and they didn't know what I was talking about. I used my manual for direction on the part replacements. I can't be 100% sure I didn't mess something up but it seemed simple enough beside the mysterious 'IRP'.

 

Double check electrical connectors to make sure they are all tight. To make the ecm "relearn" just unhook the battery for a few minutes. Afterward it usually takes a couple drives for the idle to return to normal. If the check engine light continues your new IAC valve may be bad.

 

Thanks for the help buds. I had a mechanic do a full diagnosis and he found that there are no air leaks and all the electrical systems check out. Through it all he found that it's the throttle body that is worn. The shaft that the butterfly ride on is worn and not allowing the butterfly valve to close properly, causing more air and the computer is trying to compensate. This accounts for the P0505 (idle system malfunction). I am currently trying to find a good used throttle body.
I wonder if I couldn't install a stiffer throttle return spring to help the butterfly valve close all the way?

 

Idle Control Sustem Malfunction has been solved. Scored a good used throttle body and swapped it out. It idles beautifully now. Now I want to test my old IAC to see if she really was bad. Or maybe I won't waste my time.

So, if you get a P0505 code after you have changed O2 sensors, throttle body gasket, and IAC, it could be that you have a worn throttle body that is not allowing the butterfly valve to close properly.

Important Things I Learned: 1. it is proper to change the throttle body gasket when ever you have the throttle body off and torque the throttle body fasteners to 13 foot pounds. 2. If you replace/ clean your IAC it is proper to replace the O-ring type IAC gasket. 3. When replacing your PCV valve replace the grommet also.