1995 civic 1.6 vtec. on occasion the idle fluctuates from 1-1.5k. it also overheats when not moving. could this be the o2 sensor?

 

A bad O2 sensor will usually throw a code. Is your Check Engine Light on? If not, the most likely culprit is your thermostat. The high idle could be coincidence or the ECU could be correcting for all the hot air your intake is sucking in from an overheated engine compartment.

 

theres no CEL and my idle only fluctuates on occasion but it overheats all the time while at red lights.while i had the hood up i noticed my o2 sensor wasn't tight, like i could wiggle it a little. the engine was hot so i didnt wanna get burned trying to tighten it. could that be my problem?

 

The O2 sensor isn't active until it's warm. (open loop) But you def need to tighten it.
If you're fine up until you hit a red light, is your fan turning on?
Your fluctuating idle is probably related to you IACV.

 

Exactly what I would check. If the radiator fan isn't coming on it will cause the engine to run hot when stopped and I would clean the IACV to see if that helps with Idle.

 

well after letting it cool some, I went out tightened the o2 sensor. and i checked my coolant and it was really low and cloudy. i also had coolant sitting on my fan shroud. so i just filled it up with water (dont have coolant atm). drove it around the block a few times had no problem came back parked it let it idle and the temp gauge said normal and the fan never kicked on.

 

your fan should be on when you are stopped. If your coolant is low make sure to check under your car for any sort of coolant leak(turned out my drain plug was slightly loose. had a slow leak which caused air bubbles and loss of coolant, via overheating) if there is no leak bleed your coolant by letting it idle take a rag and squeeze the big coolant hose untill you see your coolant and it isnt cloudy/any more bubbles.

do you have an IACV? if not it will do that, sounds like your TB spring may just be getting a little stuck. let us know

 

theres no puddle under the car and the drain plug is tight. next oil change im going to flush the radiator and replace the cap. im also going to clean the fitv and iacv to see if that will correct my idle problems.

 

ooo. low coolant level, with no leak, and cloudy is not good news. Most likely a blown head gasket. You could take it in to test it or buy a compression tester and do it yourself if you're relatively mechanically inclined.

 

make sure you fill the coolant with the heat on max and when the thermostat opens. combustion gasses could be leaking into your coolant making it cloudy, try this after you fill the coolant to the top of the rad check for any bubbling. bubbling could mean a headgasket that is about to go out.