2G CEL with Cose P0505 - HELP

[prosser9981]

I got ambitious one day and decided to pull my throttle body to clean/check for any residue or carbon buildup.
After unbolting the TB, I pulled the sensor wires and throttle cable, and slid the TB out.
I cleaned with a good throttle body cleaner, reinstalled everything and after 30-40 minutes of driving the CEL popped on, and idle would sit from 1000-1500rpm.
Scanned and reads code P0505(Idle Control System Malfunction).
I looked into this and it said it could be a faulty IAC motor, so I replaced with a known working used part and cleared the code. Everything seemed fine, then after another 30-40 minutes the light came back on and the idle was between 1000-1500rpm.

All vacuum lines are reconnected and in the proper location.
Sprayed starting fluid around the TB to check for leaks and nothing happens.
If anyone can shed some light on this, that would be great.

 

[ChrisKROSS]

Maybe this could help... P0505 IAC (Idle Air Control) System Malfunction

 

[prosser9981]

Thanks ChrisKROSS. Great site.
I took off the current IAC and tested the resistance with an ohms meter and found 2 terminals which didn't show any reading(or dead).

I put on a used working IAC which all terminals tested good. After installing, I have the same problem. The idle is constant around 1500rpms. When I disconnect the IAC and start the motor I get a bounce between 1000-2000rpm up and down.

Does the TPS have anything to do with this?
When I disconnect the TPS and restart, nothing changes. should it?

 

[90gsx_luis]

I'm having the same problem. I replaced the IAC with a brand new one and it still did the same, idle when I start the car is about 1100 after a bit of driving the car it goes up to 1500 to 22-2300 give or take, if I tap the gas pedal it will drop down to 1100 or so but will rises again when you drive off and come to a stand still. Anyone have any ideas of what it could be ?

im driving a 98 gst unmolested

 

[prosser9981]

My BISS spring had gotten lazy.
I adjusted the BISS screw with the headlights, and stereo on, that way I was drawing normal power as I would normally.
I then adjusted the BISS screw on way or the other until the idle was where I wanted it, and put a gob of clear silicone in the hole on the TB so the screw wouldn't back out again.

Hope this helps.
But remember where yours is set before playing with it, that way you can put it back if it gets worse.

 

[miguelmcv]

Or you have another bad ICS or your old ICS fryed your ECU.

Remove your ECU and open it to see any signs of burn, leaking cups or some sore of shety smell.

 

[jason6989]

I have the same issue, after a cold start when my car is warmed up the rpm just goes straight up to 1500 and drops and it keeps doing that. even after i cleant the IAC