mattf22b1

I have a 94 civic hb (UK model) and the idle seems to be acting up when I take it on the highway. It idles between 300 and 500 rpm when idling normally but after I take it up to 70 or 80 it idles at 1,500 rpm plus..my first thought would be to check the icv but as its carbureted I don't know what to check. Is it possible its happening because trans/clutch fluid is low? Any help would be awesome the engine code is d13b2 lightly modified.

B20DelSol

Is the throttle plate getting stuck open? Also, is there a dashpot on the carburetor? Granted, I have seen this on dpfi so far only, but if it has a dashpot, they sometimes develop a leak and will not retract all the way back. In which case, you have to bend the tab on it to bring the idle back down.

Ryan Lwin

Force close the throttle plate by pulling up the throttle switch that's attached to intake manifold with throttle cable attached. If that lowered your RPM, you either need to adjust the throttle cable or your switch is bad.

mattf22b1

Yes it does have a dashpot..the throttle plate doesnt seem to be getting stuck open, I would assume something is getting stuck, once the idle is higher the rpms are higher throughout the gears ( not good on fuel consumption) what switch could be bad? Im guessing to adjust the throttle cable is the same on a fuel injected engine, turn the nut on the cable about a half turn?

mattf22b1

bump* I have adjusted the throttle cable slightly and it seemed to work but only temporarily. I dont know if the throttle plate is getting stuck..im guessing that is under the carburetor and is the same kind of thing as the throttle body on a fuel injected engine?

Ryan Lwin

There's only the throttle plate and switch that is affected by gas paddle. Disconnect the throttle cable from the switch and force close the throttle close by pushing down the switch.