99 Integra GSR with stock motor with 90K miles. All started with a blown head gasket…rings were bad too.

Changed the head gasket, rings, and rock bearings. Polished the head, sealed the valves. Only problem seems to be with the rough Idle at cold starts. In the morning at a cold start with AC on, the rpm drops to 500 or so ..the needle goes back and forth from 900 to 500. After a while it settles down at 900 rpm. Its more like it has hard time idling and drops to a point where its going to die.

My mechanic says it could be the Idle air control valve (almost #50 for OEM). Question I have is, if the problem is with idle air control valve, should the rough idle happen ALL the time? In my case its only at cold start.

 

how are the wires?

mine was doin the same thing i replaced the wires and now it purrs like a kitten


if your idle air control is bad im pretty sure you will throw a code too

 

Plugs are new...not the wires

It is throwing a code that its running rich.....I have a CAT set up ( 2.5" flange is welded to a CAT which has only one bung for the first sensor . Second O2 sensor is not used ( 96 to 99 GSR's have two sensors in the stock CAT)

Bigger question is why it happens at cold start?

 

I don't think that the IAC would throw a code... but you could always pull it off and try cleaning it. Slap it back on, and see if your problem goes away.

 

I was searching and found this thread ..
https://honda-tech.com/zerothread/2153910

Most of the time, erratic Idle is caused by a disturbance in the vacuum system, the engine will continuously try to compensate for the loss or gain of air coming into the intake. When you start your car and the engine idles, air bypasses the throttle plate through a couple of holes, one from the FITV and the other from the IACV. The purpose of the FITV is to let extra air in when the engine is cold to help it idle and retain the proper A/F ratio. After the engine is at normal operating temperature, coolant flowing through a thermostat in the FITV heats up a substance inside it which pushes a little plunger that closes the valve that's letting air through on the other side, at that time the IACV will control the idle. The main difference between both of these systems is that the FITV is mechanically controlled and the IACV is computer controlled.

 

Changed the Idle air control vlave to a working one...No change. Idle is "dancing" up and down at cold start...infact when you roll to a slow stop, some times the engine shuts off...

Weird thing is it happens only when the engine hasn't reached normal operating temprature. After running for a while, the idle is pretty stable.

Check engine light comes on some times. Code says " System running rich"

Can it be a O2 sensor because of which my fuel /air ratio is gets screwed up?

 

Anyone wants to guess?

 

bad map sensor?

 

Did you ever find answer to this/solve the problem? Often when I just start up my '89 Accord (carburator) it will idle up to 2,000 then fluctuate between 1,000 and 2,000. When I'm driving it'll idle between around 500 and 900. It also shakes sometimes when it is idling, which I was told is normal. I brought it to a mechanic who said there wasn't any idle issue, but people who ride in my car with me do note that it idles high at start-up and that's something I should address. I don't really know who to listen to.

I was told the EGR needs to be replaced before next smogging - in two years. Do I clean the IACV? Is there an IACV in a carburator model?

This is my first car and I'm just learning everything.

Thanks!