My car has a bit of a choppy idle when it is cold up until it reaches (either open or closed loop, i cant remember) and then it idles really smooth. i have a MAF descreen. Would this cause it?

 

Bad o2's

 

IAC could be stuck.

 

no codes. O2 sensors would set a code for sure. as soon as I unplug that MAF, it idles perfect. i'm gonna put the screen back in and see what happens.

the IAC is a good possibility.

 

Actually the o2 sensors can be slow to respond, slow enough to cause issues, but not throw a code. In the case of your issue here, I do not think they are your problem though, as the PCM is not using the o2 sensor readings on a cold start, as its in open loop at that point.

I'm assuming you have cleaned the MAF sensor wires. I would put the screen back in and reset the PCM as you said. If that doesn't fix it, take the throttle body off and clean it up really well, including the IAC. Check for an air leak in your intake path.

 

Mine idles rough at first, then settles to a nice choppy idle, something about a cam.

-Rick