Originally posted by ryewdedyet
According to the S/M (shop manual) the idle speed for d16y5, d16y7, and d16y8 96-99 Honda Civics is 700 rpm +/- 50. So when the car is fully warmed up, meaning that the fan has come on once, the idle should be between 650 - 750 rpm.
Before you adjust the throttle cable you might want to do a simple visual inspection. There are several reasons why an idle on a car my be higher than usual. Usually it's a vacuum leak of some sort. You might want to inspect all of the hoses that are connected on your Civic or car. Even better, connect a vacuum gauge by "t"ing it to the fuel regulator hose or the EGR hose (if your car has an EGR). The vacuum reading for a 96-99 Civic when it's fully warmed up will be around 20 psi. The higher the vacuum the better.
Secondly look at the temp gauge on your cluster to make sure that is not at the "cold" level. If your engine is cold then the computer will tell the fuel injectors to deliver more fuel. thus causing the idle to raise.
NOTE: you can't really depend on the temp gauge on your dashboard 'cause it may be broken. So the best way to test your car is getting it hot by reving the engine while you're at neutral and waiting for the cooling fan to turn on. If it turns on that means it getting hot.
Third, check your ignition timing with a timing light. If your ignition timing is advanced that too will also raise the rpm.
Fourth, your O2 sensor my not be warming up. A four wire O2 sensor has a seperate wire that heats up the sensor so the car can go into close-loop faster.
That's all I can think of for now. But before you start taking things off or adjusting things on your car, it'll help a lot if you do some diagnostics / inspection. It'll ease your mind a little and will help isolate the problem.
good info man... I'm impressed. :thumbup: