I have a 97 Civic DX coupe. After the enginge warms up, at idle, it wants to run kinda rough. It just started recently. Going through the gears, it seems to run just fine. Can anyone point me in the right direction as to what might be going on.

 

how many miles since the last tune-up.
no codes ??
could be plug wire, pcv valve, air filter.

 

I just bought the car recently with 150,000 miles on it. Tune up? Not sure about. Air filter? New air filter. As far as a pcv valve, I don't think my model has one. I've looked all over for the pcv, if there is one can you tell me where it's located. The car has thrown no codes as of yet.

 

open up the hood after dark and start the car.
see if there are any sparks flying - bad spark plug wires may show up.
if you do not see any sparks, i would still do a tune-up since it is unknown when it was last done.
plugs, rotor and cap.
i pretty sure you have a pcv valve.

what engine:

4 Cylinder Engines

4 Cylinders 01590 1.6L MFI
4 Cylinders 01590 1.6L MFI VTEC-E
4 Cylinders 01590 1.6L MFI VTEC

 

I just replaced my pcv valve, 95 Civic LX, D15B7 engine
There is a hose that goes from the intake manifold to the valve cover. The hose is about 1 cm wide.
On the top, backside of the valve cover, there is an L-shaped plastic tube that sticks up and then into that tube. It's a bit difficult to pull out because it's under the fuel rail and injectors and intake manifold, but I used a wrench, which ruined the old one. Anyway, it is between the two fuel injectors on the right hand side of the engine.
If you buy a new PCV valve, you can see what it looks like and then you can scan the top of the valve cover to find the matching part.

 

i'm having the same problem. i have a 2000 civic ex JRSC. runs beautifully except during idle its real shaky and the rpms just die untill it revs itself when it gets low.

 

i suggest seafoam... http://www.seafoamsales.com/motorTuneUpTechGas.htm
think u said ur cars at 150, 000kms so there is maybe build up of carbon ect. on valves/injectors which would give a rough idle. but then when your going through the gears your working your engine more so the carbon buildup doesnt have as big of an effect. just my thoughts.,.... anyone second that?

 

I actually used seafoam a while back, didn't help the idle shaking much.

 

a couple of things you can look into... dirty throttle body and idle air control valve (IACV/EACV). Try the other suggestions as well.

 

Spark plug gap and perhaps cleaning. Easy check and fix if it's the problem.