Rough Idle and Overheating
 

So the problem, hopefully separate, is that I am having a rough idle and my car is overheating slowly at idle. I drive a 2004 Civic EX Coupe automatic.

Rough Idle
On a cold start my car is idling at about 2000 and after it heats up and is put into drive it idles between 1000-1500. Now a few months back, around late September, I was getting a P003 code (Misfire Cylinder 3) and since I am tight on cash I tried to see if I could diagnose it. What I did was swap Ignition Coil 2 with Ignition Coil 3. The CEL came back with the same code. So I swapped spark plugs 2 and 3. And the CEL never came back on but it still is idling rough.

Overheating
Now when I first bought the car, in Feb 2012, I had a similar problem but my pops took care of it for me, by getting the thermostat changed, but I myself didn't really care to check into it. Now I'm older and want to learn so here I am. Back then, I noticed that my defoggers weren't working, and the car was always cold even after remote start. And one night it approached Hot as I was sitting in front of my house after driving. Now like I said, I wasn't into learning and figured, "Hey my dad will fix everything!", so I didn't pay it much mind. Now I want to learn, and I am having the same problem.

Now the heat blows cold, even after remote start, but will heat up after driving, but cools down after stopping. Defoggers won't work unless heat is blowing hot, but both engine fans do work. I don't think it's the head gasket because I check both coolant and engine oil, no milky discoloration. Coolant fills overflow after engine heats up. Also if I idle lets say in a car wash line, or in a parking garage line, or just in front of home, after about a minute or two the temp gauge will rise to hot but after driving will go down.

Like I said before, I was tight on cash so I was trying to take the easy way out, but I've been working and saving, and the holidays are coming up so I think I could get extra cash help. From everything that I've read, I've come to the conclusion that it's the Coil Pack and/or the spark plugs that need to be replaced, and I need to get a new thermostat.

Any suggestions?

Re: Rough Idle and Overheating
 

It's super low on coolant,
you probably can't find any external coolant leaks,
it's blown the head gasket.

Ignoring the blown head gasket and letting it overheat repeatedly has likely damaged (warped) the head. Misfire is likely related to this.

Search here for all the info you can stand to read.

HTH

Re: Rough Idle and Overheating
 

Thank you man, I appreciate the help. How much do you think it will cost for parts and repair? Or should I go through the site and look?

Re: Rough Idle and Overheating
 

Prices vary widely. No way can I guess....I don't even do that at work -- and I do this for a living.

Prices will depend on your locale, how much work needs done, what other work needs done while it's apart, how bad the damage is, who does the work, where you get parts, etc.

Re: Rough Idle and Overheating
 

Update:

I brought it over to a reputable shop, and it wasn't the headgasket. My overheating issue was that I was adding coolant into overflow tank (white tank with fill lines) and I guess I was suppose to put in in radiator cap. And my idling problem was that my spark plugs were rusted and mismatched (because I blew my engine and the mechanic I went to just put a junkyard engine in and nothing else).

So if anyone reads this, definitely read the Overheating and Idling sticky pages before assuming head gasket. Also get an OEM radiator cap like they said.

https://lh6.googleusercontent.com/-P...o/IMG_2621.JPG

My final cost was $595.32. I pretty much got a tune-up, and additional fixing up of what the other mechanic said he did.

Re: Rough Idle and Overheating
 

So...your radiator (cooling system) was extremely low, right? Where did it all go?

Did the first shop not bother to fill it? (Surely not!)

Um, I don't remember that info in the original post. Might have been handy to know.

Maybe your used engine also needs the head gasket job. Sure seems like most need it sooner or later. And if your mechanic (no matter if reputable or not) isn't super familiar with this particular engine, he may not notice any head gasket problem.



I see they found loose alternator bolts. Good catch! May have saved you a PCM!

Re: Rough Idle and Overheating
 

I should have included it in the beginning, but I felt like I would be judged lol. And the new mechanic that I go to, he builds Hondas. I don't want to count any chickens before they hatch, but as of right now, the car is running great, no problems, idle is smooth as butter, and heat blows hot without the car moving.

Re: Rough Idle and Overheating
 

g'luck.

hopefully that was the case.

but that sounds awfully like the exhaust gases passing to the coolant, and then pushing the coolant out of the overflow. (AKA blown headgasket in 7th gen civics...)

If overheating comes back, please use the two easy methods described in the first post here:

https://www.civicforums.com/forums/3...reference.html

Re: Rough Idle and Overheating
 

NOW you get judged for leaving out important info! LOL
I've worked with a whole lot of Honda dealer techs that couldn't diagnose these head gaskets until they become catastrophic failures.
I've had to demonstrate my methods to every person in my shop....But some will never get it.


*I* didn't think my methods were unorthodox....

So...again-- where did the missing coolant go?