I'm trying to understand the strange idle behavior of my S13 SR20DET.
When the radiator cooling fan turns on at 87 deg the revs go up from 950 to around 1200 rpm, and Datascan shows the "closed TPS" switches from ON to OFF, and the timing goes up from 15 deg to 30 deg. When I was in bumper to bumper traffic the other day idle went way up to 2000rpm and only came down when I could gather some speed or if I parked the car and waited for the temperature to drop.
I initially thought the FICD was connected by mistake to my cooling fan instead of the AC fan (it's an engine conversion into a Peugeot and I'm not running AC) so I connected some jumper wires between the IACV male and female connector plug and tried unplugging the FICD wire while it was revving high but it made no difference. However when I unplug the ACC wire the revs dropped to 700rpm. This says to me that it's the ACC creating the high revs when the fan kicks in and not the FICD, which is supposed to increase idle when AC is turned on.
But how does the ACC know that the exact second the cooling fan has kicked in, or even the ECU for that matter? And why does it take the TPS off "closed TPS"? Could it be a problem with the "wax pellet" in the IACV which controls cold idle?
TPS and timing have been set at factory settings and car idles fine if a little high at 950rpm when "closed TPS" is showing ON. I can't seem to get a lower idle than 950rpm though even going through the factory procedure. Any ideas?