7thGenSE

So I have a 2004 Civic and it usually runs perfectly. However occasionally, say 1 out of every 20 times I drive it, the idle is terrible. It's will rev to 2000 then drop to 400-500. Then when I'm driving it will run fine until I come to a stop light then it will drop to 450 RPM. It doesn't stall but shakes pretty violently. If I step on the gas it revs up as it normally would. Any ideas to resolve this would be awesome!

mikey1

possibly your IAC ?

is your CEL on?

7thGenSE

Nope... I went digging the last few hours and found unsettling things... This for starters http://imgur.com/QmiQDoG . Im no mechanic but Im guessing that could be a big issue? I was wondering just how this could have the grime built up so I checked the air filter... thats when I discovered there was no air filter... So Im going to guess this is my problem? I will be cleaning it out tomorrow I love previous owners who neglect air filters... I bought the car a couple weeks ago.

PS. While removing the negative terminal on the battery to disconnect the wire to the air box I found this http://imgur.com/WnlE0lB not connected to anything? What is it for?

bsmiley

Looks like a throttle body cleaning is on the to-do list. While you're at it you should clean the IAC valve. Its easy.
Speaking of the to-do list, I'd probably disconnect the battery and get that ground lug in the second picture connected, ASAP. You did good to find that. I believe it connects to the chassis to the right of the fuse box.

7thGenSE

Well yeah no doubt! I had no idea! What are the risks of disconnecting the sensors? I hear EricTheCarGuy saying the car has to relearn the position of the throttle body?

7thGenSE

I also should say, while I was taking the air box off the TB i noticed the rubber piece connecting the two is cracked really bad, I imagine are is getting in there. Is that causing the idle issues? Its before the throttle plate?

ezone

Look at all the barnacles! Did you pull this out of a lake?


Yeah, clean it. Clean it all. And the IAC.



Do NOT hook this up yet, follow it to see where it goes. Looks like an amplifier power wire to me.




Also note that NAPA sticker that tells when the timing belt was done or is due.


Yes replace the rubber ring if it is cracked and letting unfitered air in. No, it won't cause idle probs.

After the cleaning, do an idle relearn.

7thGenSE

How do you do an idle relearn? If I disconnect the sensors and take the entire throttle body off do I HAVE to do a relearn?

Also believe it or not, I did not pull it out of a lake. There was apparently no air filter from the previous owner... That combined with the winter up here... *shivers*

ezone

Not for disconnecting sensors, but YES for after cleaning the throttle and IAC.

I read that, I was looking at what appears to be rust and scale all over everything outside the throttle area. You must be in the rust belt or far North?

7thGenSE

Ahh, Could you explain or provide a link to a good relearn procedure for my engine?
Yeah I'm in Northern Ontario... Constant salt abuse is committed daily up here

ezone

I should add: Yes because you disconnected the battery.
Clearing codes with some scanners will cause need to do the relearn too.

Warm up engine to operating temperature (fan cycles).
Turn off all electrical consumers
Let idle in park for 10 minutes.




HTH

7thGenSE

Awesome! I will be doing all this tomorrow, will let you know how it goes.

mikey1

Holy crap.....if your throttle body is that dirty i hate to imagine all the dust and debris that has entered your cylinders/combustion chamber

7thGenSE

Don't make me think of that please lol. Luckily I caught the no air filter **** now. Typing this from the auto show then picking up an air filter and cleaning the TB out. Hope it works :/

mikey1

cleaning the TB is a start but wont help much, if your TB is that dirty then so is the inside of your intake manifold

Reverb2005

AND scratched-to-hell piston walls AND gummed up EGR valve AND dirty CAT (if it still works, i.e. no codes)..... pretty much everywhere air comes and goes to and from the engine....

Clean the EGR valve while you're at it. Do it before the idle-learn.

https://www.civicforums.com/forums/1...e-up-mods.html

7thGenSE

Hey guys, here's an update!

It had been idling bad up until Sunday but not that bad. On Sunday it was finally warm enough to go outside and pay some love to my baby. I started with the removal of the throttle body, IACV and the rest of the air intake system. I gave it all a good cleaning and made sure nothing on the throttle body was sticky and cleaned it until I could eat off it. I then sea foamed the engine via cacume line, crank gas and the small amount of gas in the tank. Then drive it for 25-40 km. I returned and it was idleing so much better, sounds very smooth and has much better throttle response and over all performance. Upon returning I changed the oil and plugs and put a fresh tank of premium gas in. I have driven about 100 km now and it feels like a brand new engine!
Thanks for all the help!

Also the cable I previously mentioned turns into a red aircraft wire looking thing then enters through the fire wall along with the other cables? Any idea what it could be?

Again thanks for all the help!

ezone

It sure looks like it should be a power cable for an amplifier. Follow it the rest of the way through the car?

It's not connected to anything, so don't try to connect it to anything.

7thGenSE

It does seem to be a amp wire, looks to me like the previous owner had one but removed it before it was sold, thanks!

I also noticed the hose from the air box to the top of the engine has an inch long crack at the end where it clamps onto the engine. Would this affect idle/performance? Obviously it needs to be replaced due to unfiltered air entering.

ezone

The crack is where?

Your air filter is located where?

7thGenSE

I'm assuming the hose is vacuumed?

7thGenSE

The breather hose to the top of the crank case

ezone

The picture helps a whole lot.

If that's split open, it needs replaced.

No, it's not under manifold vacuum and won't affect idle but it still should be fixed.

7thGenSE

Couldnt get a good picture of it on my own car right now as its -25 and a blizzard lol.