Hey guys so i just bought this 2000 civic ex 1.6l d16y8. Anyway day i took delivery the waterpump took a dump so i replaced the entire cooling system short of the heater core, replaced the water pump and timing belt. Now im having idle issues. It was super low (300 range) so i bumped it up using the idle mixture screw. Oh and i bled the crap out of the cooling system. So now when i come up to a light or a stop it idles at 1200 drops to 1000 for a second then to 800 then back up to 1200 and stays for a bit, anybody have any ideas? I havent cleaned my iacv yet but plan to. Anything else it could be?

 

Besides the coolant (which you should check one more time, when it is cold, open the radiator and confirm it is full to the top), the IACV can get dirty (remove and clean) or the ECT can give flakey readings to the ECU (test with OBDII live data or test sensor with ohmmeter).

On an EX manual, unplug the IACV and set the air screw for 420 rpm, i.e. barely running. This is only for two wire IACVs, it does not apply to EX auto which has a 3 wire IACV.

 

Ok ill check the coolant again, maybe try and bleed it some more, as for the iacv, its a two wire, ill clean it, and whats this ECT you speak of. How do i test it with my ohm meter?