kateri.bean

Hello all! So I have a Honda Civic LX 2004 and I've had it for 4 years now and it's almost at 200,000 miles. I have been taking excellent care of it but the other day it gave me quite a scare! I was coming home from work when it suddenly started shaking/vibrating and making an unusual noise. I put it in park where it proceeded to give me a very rough idle. It drove me home though (no check engine light ever came on) and later I re-started it and it still gave me a very rough idle and even a little hesitation to start.

However, the next day it started up just fine and drove just fine! It has been driving fine and it's been theee days since that rough idle. Today I brought it in to my mechanic and he could find no issue...he even test drive it.

I rely on this car for everything and have put a decent about of money into it (new spark plugs, new timing belt, new water filter, oil changes always on time) so I'm just wondering what it could be and if it'll occur again? Any thoughts?? Thank you!!

Wankenstein

Automatic or manual transmission? If it's an automatic at what mileage was (if ever) the ATF drained and filled?

Just a guess but by your description it sounds like a momentary cylinder misfire. Could be a spark plug coil beginning to fail (weak)? You can check for spark by doing a power balance (drop test)...with the engine at idle lift each coil one at a time and listen for spark and idle drop. The idle is supposed to drop and engine run rough when a coil is lifted and if it doesn't change the idle then there is a cylinder misfire.

Also when the engine is cold check the radiator level..air in the coolant system can cause a rough idle but it's usually consistent and not intermittent.

ezone

Elaborate.

kateri.bean

It is an automatic and I have never changed the ATF I don't think. The noise was just metallic and from all the vibrations I believe.

I just had the spark plugs changed last November...could they already be weak? Thank you so much for this additional info!

Wankenstein

An ATF drain and fill is considered by many to be routine maintenance and would be beneficial.

Doubt if spark plugs are but the coil(s) which connect to the spark plugs could be. The problem with intermittent issues is that many times the problem has to be happening during testing to isolate the fix.

Ezone, could a momentary electrical load issue/surge cause OP's complaint?

OP: as a side note you posted in the 8th & 9th gen and your's is a 7th gen ('01-'05). Not harping..just for future reference.

kateri.bean

So it sounds like my best bet is to bring it in for some more routine work and have them look at the coils and replace the ATF?

On a side note, my friend is convinced that I put bad gas in it and that was the issue. He believes that the gas station which I went to sells watery gas due to the constant flooding in the area.

Thank you so much!!!!! I really appreciate it all hoping for the best!

ezone

Sorry, complaint is way too vague so far.


NO.
If you aren't able to go into great technical detail with a description, don't even talk about car parts.
You describe the symptoms.
Better yet:
You take it into a shop while it is acting up and DEMONSTRATE your problems to everyone that will be involved so everyone involved is on the same page about what the problem is. No guessing, no trying to figure out what you are talking about.