Hello I have a 90 honda Accord 5 spd and have two problems. Thr first is my surging idle I have disconnected my tb and cleaned it all up. then did my iac valve then my fitv valve nothing changes it. also If I adjust the idle screw down it wil steady for a min then starts surging again ? I have tried bleeding the cooling systrm but it doesnt seem to purge all the air out seems like there is always a little bubble in there. My second probelm could be related but I doubt it my fan wont cut on with out direct power I can disconnect the plug to the sensor on the themo housing and stick a wire in to complete the circuit and it cut on but doesnt byits self I have switched relays and sensor nothing changes?

 

Sounds like there's too much air in the coolant, that could cause both of your problems (coolant not reaching the fitv to tell the ecu the engine is warm=surging idle, not reaching the thermo=fan doesn't switch on)... Make sure you're doing the proper procedure for bleeding the air out til there are no more bubbles. Don't mess with the idle adjustment screw, you'll just mess things up since that isn't where the problem is.

I'm new to working on cars but it seems to me like that is your problem. Others will chime in to confirm... holmnes and madmike's word is to be taken as gospel LOL

 

you obviously have a vacuum leak ...get a can of carb cleaner and gently spray around the intake while the car is idling til u find it as the idle will change... you could also have loosened the idle adjust screw too much which can look like a vacuum leak

 

The air in the coolant will cause the idle surge, very similar to a vacuum leak would. the best way i have found to bleed it off is to leave the radiator cap off while bringing the idle up to 1500rpm or so (using your hand on the throttle body) so you can watch the radiator, there will likely still be some very small bubbles after complete but all the trouble-causing air pockets will come out, i prefer to do this process twice...but thats just me. when you top off the coolant its best to pour very slow so you dont create more air pockets. of course double check your vacuum lines since you were working with the tb

 

Should your heater be on the hottest temp and blowing on full when you bleed the coolant so that you get any air bubbles that are in the heater core? Or is the coolant in the heater core always flowing through the entire cooling system regardless of whether the heater is on

 

during a flush you would have the heater on but it isnt necessary when bleeding it out