I have a 94 Civic DX 1.5 16 valve. For quite sometime now my idle surges up and down once the car is warmed up. I have cleaned the valve a couple of times and it hasnt helped. Recently I decided to try something. Once the car was warmed up I unplugged the valve and it stopped idling up and down. Then plugged it back in and the idle was still fine but the engine light obviously came on and I drove it about 10 miles and parked it. The idle stayed normal. I then shut the key off and started it back up 5 minutes later. The engine light went out and it immediately started idling up and down again. So I repeated everything i did and it did the same thing. Once I shut the key off and turn it back on the light goes out and starts idling up and down. For some reason when I unplug it the idle goes fine and the light comes on but once I shut the key off and start it back up and the light goes out it starts all over again. Any ideas if this could actually be a bad valve or is it something else?

 

In for an answer. Mine seems to have this happend SOMETIMES. And when it happens its always after its up to normal temperature.

 

1) Bleed the cooling system.

2) Test the ECT sensor and the TPS.