Couple weeks ago i cleaned IACV and FITV, changed spark plugs, rotor with new cap, fuel filter, alternator and belt, and changed oil.

I was wondering if it's normal to have around 500 RPM idle during the day, after warm up, and have around 800 RPM idle during the night.

 

Thread bump, anyone know? I have not yet resolved this weird problem

 

the Haynes manuals says it should idle close to 700rpms

 

Is the PCV valve/hose clogged?

 

I have checked it and its clear. Could it be the intake air temperature sensor?

 

Bump/

 

bump for info my 92 vx does this also!

 

turn up the idle screw on your TB..i had the same problem and i cleand the iacv and fitv and turned the idle screw up now my car idles right under 1k.. but every car is different.. goodluck.

 

When idling at night, are your headlights on? That'll kick up your idle by a fair bit.

I'm not convinved of the tach's accuracy (especially in the far lower range), can you check your rpms directly?

 

Alright will try this.

 

Well, that didn't work, BUMP!

 

You have not said what car/engine you have. Any CEL codes?

Did you follow the service manual procedure for adjusting the idle speed?

 

Don't you unplug your IACV and then adjust the idle screw? If so, yes I did. No CEL either.

My car is a bone stock 95 civic LX 16 valve auto

 

Did you hook up an external tachometer? The cluster tach is inaccurate in the low rpm range.

 

Alright, I'll try to find an external tach. My local Checkers auto store should have it right? I'll give them a call.

 

this is a good one! cus i have the same problem often

 

I turned on my lights this morning(gloomy weather) while starting up the car, and while I was driving to class, my idle was good at 800ish, it usually a low idle without my lights and AC on.

I don't turn on my lights during the day when its gloomy like this, could it be something to do with voltage/ground problems?

 

ELD it sounds like. The Electrical Load detector. It would sense the extra draw from your battery and compensate. If only you had Hondata this problem would be an easy fix...change IAV duty up or adjust idle point and boom would be running perfectly.

I would check the FITV which is right below your TB (if you have one). Take this apart...clean it and adjust the white plunger a turn out. This may help...but really idle is controlled by the IACV and it sounds like yours may be on its way.

Another thing I would do is take and bleed your coolant. Crank that defrost up on high while doing so and wait for the fan to kick on. Maybe there is a bubble...though that usually causes surging.

 

It's normal for the idle speed to increase with higher electrical load. Again, it sounds like your base idle speed is set too low and needs to be properly adjusted.