Idle.. changes with mods?

[AnthonyR23]

Hi.. do certain mods change how low the engine can idle... I can't seem to get it to idle less than about 700 800 rpm.. and when I adjusted the set screw and re adjusted the tps to get around .9 volts I still can only get it down to about 700.. actually had the throttle stick because I think I had the set screw too low.. with underdrive pulleys.. headers... is it possible for the car to not be able to idle lower.. and does timing affect how low the car can idle?? I get code 13 which says that the engine could not perform the lower rpm test.. any ideas???

 

[4G-KDMP]

less than 700 rpm, why?

 

[AnthonyR23]

well I read that you should be able to set your idle screw to 600.. with the iac motor plug detached.. from there the iac adjusts the idle apparently...... anyways so after adjusting the screw.. you have to readjust the tps to make sure voltage is between I think .6 and 1.0

So.. I am getting this error code 13. That low rpm test could not be completed.. any ideas??