I have 2005 Honda Accord 2.4, lately when driving on the highway for 30 minutes or more, when I get off the highway the idle is rough but eventually smooths out. This has happened a few times ???

 

Have you had any recent work done on your car?

Does the check engine light turn on while driving? Does the D (or D4) light on the instrument cluster flash?
You may want to stop by an autoparts store and have them scan for codes anyway.

 

No recent work done on the car.

No instrument cluster flash.

Check engine did come on once about 4 weeks ago it was a p0141 code, but the check engine light turned off by itself.

 

Anybody ???????

 

An intermittent problem is tricky to diagnose.

What do you mean by rough idle? Please tell us what you observe when the car acts up.

Does it always happen when decelerating coming off a highway after 30 minutes of driving? Does it happen any other time?

 

Is this the same car you are referring to in the other thread which talks about burning a quart of oil every 650 miles? If so, the oil consumption may have clogged your catalytic converter.

 

Catalytic converter was replaced, the rough idle is the same as one of the cylinders missing but not as harsh, again this only happens occasionally after a 30 minute drive or longer when I get off the highway and then clears up.

I have 70,000 miles on the current spark plugs ( 100k spark plugs) Im wondering if I should change them ?? And the ignition coils I believe they are original.

Other than that the car runs great ?

 

Have a cylinder leak down test performed; that will inform you whether the engine is having issues or worth saving.

 

When coming to a stop do you have the a/c on?