ok so here's what the truck is doing, sometimes while driving the rpm's will get "stuck" at 3k or higher and will stay that way for quite some time. you can hear a whistling noise from the iac valve also until it finally decides to close. It will also act like its in limp home mode sometimes and will start in 2nd gear from a dead stop then shift to 3rd when the rps/speed are right. the only trouble code it's throwing is the P0505 code. probable causes are vacuum leak on engine, dirty throttle body, iac motor defective, or poor electrical connection to the iac valve.

and here's what i've thrown money at.
new iac valve
plennum/ intake gaskets
all vacuum lines checked
new tps
cleaned throttle body
seafoamed intake, oil, and gas

i've been looking for the expected voltages on the iac motor but I haven't turned up anything as of yet, but as soon as I get them i'll be getting out my fluke and a powersupply and testing the motor at expected values and testing what values its actually getting.

any ideas on why it would be sticking though, even when its been cleaned?
also any other help would be GREATLY appreciated.

 

this doesnt have the answer but has alot of ideas you can try to fix it. Maybe one of them will work for you.

Hopefully it has some useful informaton for you


https://dodgeforum.com/forum/dodge-r...0505-code.html

 

I've been fighting this problem for years now on my truck lol. I have even put a fresh engine in it now and still nothing. My last and final thing I'm going to try on my truck is a new computer.

 

I had a simular problem and found one of the leads on the pre O2 sensor(in the cat) to have worn through and was shorting aginst my tranny pan causing the PCM to freak out. I replaced the o2 sensor and have not had an issue since.

 

well thanks for the help I appreciate it. I took the iac off and adjusted the needle a bit and I actually managed to get the idle down to about 700-800 which is much better than the 1.1k minimum it would run. I took the battery off to reset the pcm but it still throws a code as soon as its hooked back up and cranked. I suppose i'll just have to drive it a bit and let it re learn its sensors and proper idle. good news though it dosen't get stuck at 3k while driving anymore, always sounded terrible at a red light with the engine still at 3k rpms and a loud *** exhaust