Ok i have a 92 civic si hatch, all stock, that when i got it was great, after having it a while it slowly started to get an erratic idle when i first start it up, now it does it every time when the motor cools a lil. Only does it for about 3 mins, then quits. I got a new the IACV, cleaned and adjusted the FITV, got a new PCV valve, checked for air in the Coolant, sprayed and checked for vaccum leaks. replaced the TB gasket. Also have changed what fuel i use. I was putting in ARCO the cheapest gas, now i am putting in Shell. I was told that also might be the problem. It wasn't. I have no idea what it could be, any suggestions would be much appreciated!!!

 

Have you try cleaning the throttle..

 

Have you checked the idle thermo valve? Its located under the throttle body. Most obd 1 hondas have them and they go bad. Also make sure you dont have any air bubbles in the coolant. I had a 92 prelude with same problem and air bubbles caused the erratic idle.

 

Bleed the coolant. The fitv could be bad. I had an idle problem similar to this. I had the wrong sensor plug goin to the iacv might check that. This was on my eg with a sir swap

 

Yes I did clean the Throttle Body... I have checked the coolant for air bubbles, but have not drained the coolant and refilled it. For the fast Idle Thermo Valve, I took it apart, cleaned it, put it together, then adjusted it and I still have the problem. So I guess It could be bad. Also I went and had it looked at, at a shop for a quick second. They couldn't really fit me in at the time but the guy noticed that the timing was way retarded. So he adjusted the timing! That whole day it stopped, but the next day it started all over again w the erratic idle.

 

No other Ideas?

 

You can have a tuner change your target idle and sometimes fix idle problems as long as you have ad chipped ecu with some sort of management system. I run crome. But spraying for vacumn leaks is kind of just a rough test sometimes its a real small leak. When you bleed your coolant do you lift the front of the car up? Also could be bad head gasket. Notice any milkiness in the oil?

 

No I do not lift the front of the car up when I bleed the coolant.. I will try that and I have not noticed and milkiness in the oil.. Oh and my ECU isnt chipped..

 

IACV, TPS, MAF, check all your gaskets. Clean throttle body. Check if oil is milky from headgasket possibly being bad/going bad. Vacuum leaks, etc. Check it all. GL. Keep us informed.