DownfallEclipse

I recently bought a used 2000 Civic EX 1.6L, with 134,000 miles, and am having some issues with the idle/starting up. First, it doesn't always start right away. The starter sounds normal, and the engine turns over, but I have to turn the key once, let it try, and then do it a second time for it to start. This problem usually only happens when it's cold.

The main issue though, is that once it warms up, the idle will sit right around 500 RPMS. It's usually at 600 in park, and drops down to 500 when in reverse or drive. I can prevent it from idling that low by turning on the headlights, and that will keep it up at 700, however, if the AC unit is turned on, the headlights won't help keep the idle up.

The car did it a little when I first got it but it's gotten worse in the last week or so, to the point where it has actually died when I am sitting at a stop. The only thing I have done to the car is install a stereo and subwoofers. My first thought was that the subs were pulling too much power. This idea however was squashed when I discovered turning the stereo up actually keeps the idle up. The idle doesn't even drop when the subs hit hard, so it doesn't seem to be them pulling too much power.

I also noticed, when driving on the freeway, if the AC is on, I hear the belts chirp once, and the engine stutters for that small amount of time. With the AC unit off, but everything else on (lights, heater, stereo/subs) the chirping/stuttering does not occur.

Sorry for the long post, but I want to be as thorough as possible. If anyone has any ideas it would be greatly appreciated.

Firearmor

There is a air mixture type screw on your throttle body that you can adjust that should take care of your problem. Just be sure to only adjust it when the car is completely warmed up. You want to loosen the screw so that the idle adjusts up. The hard starting is probably some bad plugs. Be sure to use NGK's, don't use any of that Bosch crap.

hb pickup

Before messing with the mixture try cleaning the throttle body & idle air control valve as shown in Gearbox's forgotten tune-up mods thread in 7th gen engine DIYs. Of course u gotta have decent plugs, cap, rotor, filters, etc. The mixture setting shouldn't need to be changed unless you've modified something.

DownfallEclipse

The plugs/cables/rotor/cap are all brand new, though I don't know what brand was used. The dealer replaced all of that before I bought it. I will try cleaning the throttle body and the air control valve and see if that helps.

I will post back after to let you know if it helped.

Too Tall

Run some fuel injector cleaner for a tank or two to clean the injectors.

Turning on the ac may drag the idle down, but maybe the ECU is supposed to increase idle to compensate. I'm not sure about your car. The chirping is probably a loose ac belt.

DownfallEclipse

So, I haven't had the time to fix this issue yet. The car was running fine, just idled low at a stop. However, now I encountered another issue. I was driving home from work today and the car would not shift out of first. When I was pulling over to the side of the road the check engine light came on as well. I turned the car off, sat for a couple minutes, and decided since home was 2 minutes from my location that I would attempt to drive home. When I started it back up it ran fine and shifted normally.

This seems really absurd to me. Does anyone have any ideas on it?