Rep Power: 0

1997 Honda Civic Ex

My car overheated a while ago, and it threw an Idle Air Control Valve (IACV) code. I made sure the coolant system was repaired. It's the winter season here in Missouri, and when I started my car in cold weather it would NOT run until the engine is to normal temp, but even then it idled very, very low, to the point of dying or almost damaging the engine. (if possible)

So.. I then took off my IACV to check it out, and it was a disaster, so I replaced it. Currently, when I start it in the cold, it will die. But, when I start it a second time and rev it at about 1.5k rpms for a second or two, it will stay running but at a very low rpm. Sometimes though, when it's up to normal idle temp, it will either run at a very low rpm, or vary to a high 1,500 rpms. But it doesn't fluctuate from one to the other, it's either a very low idle or a 1500 idle.

When I changed the IACV I disconnected battery, but I did not do the "turn it on cold and rev at 3000rpm until normal temp is reached, then turn off and start again. Any tips on what else could be wrong? Check engine light is off, but it still idles ridiculously low or on rare occasion at 1500rpms.

 
Rep Power: 0

bump

 
Rep Power: 0

have you checked your compression lately.......

 
Rep Power: 0

No I haven't, but on most of the sites and forums I've been on that has never come up as an issue, should I look into checking it? Anything else you could think of?

 
Rep Power: 0

bump

 
Rep Power: 230

Try another new IAC, you may have gotten a faulty one. If that doesn't work you could have possibly damaged the head when you overheated.

 
Rep Power: 215

a warped head can happen easily with an overheated engine. Get your compression checked. Before you go spending that money, check your coolant and oil. Make sure it's not mixing. That is another indicator of a warped head or blown head gasket.

 
Rep Power: 0

When you replaced your IACV, did you buy a new or a used one?

 
Rep Power: 0

I bought a new one and it looked pretty good.

 
Rep Power: 0

Tomorrow my father and I will check compression for any damage. I just did an oil change and it was just oil. But still, I think something did happen when it overheated so that's a good idea. It just never felt the same.

 
Rep Power: 0

Tomorrow I will also check for leaks. I'm also going to reset ECU again and see if I can get it to idle well. Are there any other signs of a warped head?

 
Rep Power: 0

Okay, so I checked for leaks on the intake, and there were none. It's all sealed up tight. What else can I do? Still has a super low idle on start up when cold and goes to 1.5k rpms when its hot (every now and then) I turn on the ac and it will drop to a good idle, but it doesn't last for long.
Have NOT checked compression yet.

 
Rep Power: 215

And there are no CEL? What exactly do you mean by low idle? exact numbers.

 
Rep Power: 0

the engine shakes like its about to die, almost makes me want to turn it off and not drive. Barely shows on tachometer. about 400 id say

 
Rep Power: 0

Another thing I should mention, idk why i didnt, i got a new engine out in, and i had them install a skunk2 intake manifold, but the thing the throttle cable spins around, it was catching on the manifold so the throttle was very sticky and revved too easily, so we ground it down so it would spin freely. But we couldn't get the idle to go back to normal, so we adjusted it manually. Did we cause a problem here?

 
Rep Power: 215

The IACV code will pop up if the IACV can not control the idle for a set period of time. Did you ever adjust your idle screw? Check for vac leaks too. The smallest leak can cause problems. Have you ever tried the carb/throttle body cleaner method? Be careful cause if its hot enough, you could start a fire.

 
Rep Power: 0

Yes we tried for leaks after I let it cool off, found none. Someone sent me an idle guide with exactly what you're talking about with the screw, it's step by step so I'm going to try that and see if we can get it all settled out.

 
Rep Power: 215

k good luck.