I've got a 1993 civic with 323000 on it. This is what I recently did to it: Pulled the head and had it completely reworked, dropped the pistons, re-ringed, honed cylinders, new bearing caps. Did the rest of the usual stuff along with this such as timing belt, water pump, (thermostat too), and new drive belts. Drove it for about a week, adjusted the valves. Problem is that it remains at high idle(1200 rpm)- this was not occuring before any of the rework. It will also surge up and down after driving for a few miles. Its almost as though it wants to kick down to standard idle but can't. Ultimately I suspect the fast idle thermo valve. But I have checked the ECT probe, checked all the lines(vacuum, etc), valves adjusted, injectors are OK, and I have no codes. The fast idle thermo has no codes associated with it and there are no electrical inputs. I've pulled the intake tube and the lower port in the throat pulls well when cold, and there is also some suction after warm up. There shouldn't be any at all. I am going to change it, but it costs 75 bucks and I don't want to overlook anything first. Any ideas??

 

test your tps