95_Civic_4dr

Whenever I'm idling at a stop with my headlights on the car seems like it wants to die. It will be at it's normal idle range around 500-600 then it will drop and the car will begin to give off a rough vibration as if it's about to shut off then return to 500. Occasionally it will rise to 1000-1200 before returning back to 500 after it drops first. It's only been doing this for about a month and at first I shrugged it off thinking it's no big deal until I was with my cuz at night and we were at a stop and the car's rpm's dropped and he asked me if my car was gonna die or what, since then it's been bugging the hell out of me.

It's only at night with the headlights on, before it started doing this it would idle at 500 during the day(still does) and at night it used to idle around 600 with the lights on.

I thought about cleaning the IACV but decided not too since this only occurs if the headlights are on, otherwise it idles perfectly. Starting to think I should clean it anyway...

I tried a quick test on the alternator by disconnecting the battery cable while the car was running and it didn't die even with the A/C, stereo, and headlights on so I didn't think that was it either. Could it just be starting to die on me? It's only a year and a half old...

Other than those I don't know what else to look for besides maybe a vacuum leak which I doubt there is one.

Any help, thanks.

95_Civic_4dr

Bump for my old thread xD

Still having the problem except now the RPM's will bounce continuously 300-400rpms after 4k and continue all the way up to 6k until I shift or left off the throttle. The engine doesn't stumble or anything so I don't think it's a problem with the motor. Any ideas? And if the RPM's are bouncing like that will VTEC still engage? I can't really tell if it's engaging or not since it's just a little SOHC motor.

Any help for an old but still existing problem would be appreciated

mister_scho

bump for some ideas on this

I have an idle that responds to accessories being switched on, and the alternator FR signal going back to pin D9 (stock VX) does drop as you turn accessories on. TB and IAC were swapped with known good parts, and the problem persists.

95_Civic_4dr

Oh man, a reply! lol

I cleaned out the IACV, installed new plugs and wires, took the dizzy cap off and inspected the rotor and cap, everything looked good. And I checked the spark plugs with all the accessories running and they had a bright blue arc and everything seemed normal. The distributor will be 3 years come Feb. so I don't think that's what's causing the idle problem. I'm having a hard time locating what's causing it cause it's so inconsistent and seems to only to do it at night with the headlights on, not during the day with the accessories on, just at night with the headlights...wtf? Despite the bad vibrations and it sounding like it's about to die, I'm starting to think this is normal... -_-

mister_scho

OK, in digging through all the electrical stuff I can get my hands on, make sure you have continuity between A16 and the wht/yel wire on the alternator, and the same for D9 and blu at the alternator. A16 is the control wire, and D9 observes the field. Both are used on US made civics.

Now, all of this is also dependent on the ELD functioning properly. Make sure you check that out as well. I'll be performing these tests tonight to make sure that everything is where it's supposed to be.

Swapped a VX into an old CX chassis, and it all runs, but the electrical is goofy at idle. So gar I've been able to compensate by setting the base idle a bit higher and that keeps it from getting too rough, but something certainly isn't working properly to compensate for the extra load.

Wiring first because it's free, then start checking for broken parts.

mister_scho

Someone who knows something about cars is going to post in this thread eventually.

Keep hope alive.

95_Civic_4dr

One day lol.

I did a valve adjustment today since the car hasn't had one in 40k-50k miles and surprisingly it fixed the idle issue with the headlights on which was great, up until I realized it does the exact same thing except now with the headlights off...go figure. So now I gotta recheck the clearances and re-do the valves