Devon Ames

I have a 99 civic ex five speed. D16y8. It has an issue where the idle wanders, typically idles around 1200rpm. After letting the car run for a bit, the idle jumps right to 1500 rpm and gets very choppy. When I give it light throttle, wether moving or not, the throttle response will be choppy. If the car is moving no matter what speed, light throttle will be jumpy and jerky. I have a cel p0505 for iacv. So I have done the following and none of which have fixed it. Replace iacv, throttle body, TPS, MAP, burped coolant system, even switched the ecu. Could it be a wiring issue? I'm lost. Thanks for any input.

White_EG1

Try unplugging the IACV connector while the car is running, and adjusting the idle screw. When you are done unplug your neg battery cable for 5 mins then start the car.


Edit: I'm not sure if 96-00's have this screw.

Devon Ames

Thanks for your input. I figured it out finally. So I learned today only 99 and 2000 civics have an air assist solenoid that screws into the thermostat housing. When I looked my car didn't have the air assist solenoid, someone before me switched the thermostat housing. They then ran the vac line from the intake manifold directly to the intake tube. I removed the vac line, capped off the two openings and problem solved. It's the end result of just by passing that AAS. car runs great, idles perfect and no cel.