Rep Power: 0

Hey, I have a 2002 honda civic with a d17 series in it. Its got 270,000 on it. Recently its developed a rough chugging idle, sounds like its not running on all cylinders. I've taken the old plugs out and they don't seem to be fouled or in terrible shape, the new plugs will go in tomorrow. It only shakes at idle sometimes and the rest of the time it will smooth out, plus it smooths out with acceleration. When it starts chugging the tachometer doesn't move. Any idea what this could be?

 
Rep Power: 145

Does it only happen during idle?

Is the check engine light illuminating at any point?

Yes and no to those questions respectively would point toward the idle air control valve (IACV), though you can get a code for the IAC valve, just not always.

Usually a cleaning or complete replacement solves the issue.

 
Rep Power: 0

The check engine light is not on and it happens during idle but also chugs a little bit until the car revs up to around 2500. When I first start it up it will run smooth and only idle rough some of the time but it seems the to get progressively worse the longer you drive.

 
Rep Power: 145

There are some other possibilities but the IAC valve is pretty simple to get at and clean out.

If cleaning it doesn't work, you may need a new one as cleaning doesn't always solve the problem.

There is a good write-up about some common fixes, including the IAC valve here:

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

 
Rep Power: 149

After you clean IAC do an idle learn.