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I am the original owner of a 2007 Honda Civic LX with 180k miles.
I just changed the spark plugs at about 150k with OEM platinum, just got rid of a check engine light for a fuel system too lean code P0171 and P0174.
Also had rough starts. I changed the upstream O2 sensor and MAF prior to finally replacing the fuel pump which was the real fix of the CEL.
Hard start issue also resolved. Car all along, had this slight rough idle at red lights but not all the time. After the CEL was resolved, I had rough idle sporatically again and threw in Sunoco Ultra which seemed to help. Gets 36 MPG if driven all highway so engine is performing well.
Any hints as to what the issue could possibly be?
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Try checking your EGR valve. It;s easy to get to.
I have 2008 Civic and lived with a rough idle for a long time and when I finally got a CEL for EGR valve issue I found it be be so gummed up that I gave up on cleaning up and just ordered a new one. Idle issue fixed after that.
Yes I was, exactly as you described while waiting at lights. I have a cheap elm327 usb scanner that I could track a parameter called “egr error” and I could see it there as well.
Do you have a video or something I can use to locate & check the EGR for any clogs etc
Or how to replace it?
hopefully its not a costly part.
Is it easy to find?Here is a picture showing the EGR, it’s easy to remove with nothing in the way- 2 nuts.
It’s probably not bad, if it was, you would have a CEL but it might be dirty as mine was.
Thats correct I do not have a CEL
Is there a video on how to clean up any clogging or a closeup picture you can send me from your car?was not sure if my response went through
but do you have a closeup pix of what it looks like in your car
and maybe a video on how to clean it upJust a thought. you might have a worn motor mount that feels like a rough idle. especially when you are really paying attention people tend to get hyper sensitive and perceive things that are actually normal or seem worse than they are.
No. engine mounts will normally be most noticeable at idle and the feel will improve with engine rpm. Also some mounts depending on how worn they are can change how rough it feels with engine harmonics. The EGR valve can defiantly cause a rough idle. Aslo on Honda valve adjustment can cause misfires and driveability problems.
ArmedsouthernEr
I had a valve adjustment done on the way to getting a previous CEL fixed for a lean code (resolved by replacing the fuel pump).
The slight rough idle had been happening prior to this & remains sporadic when I am stopped at a red light – it doesn’t happen at red light all the time which is really weird to me.
It sometimes kicks in as soon as I come to a dead stop and sometimes it takes a few seconds after I stop. There are times when it will be smooth for the entire 20-30 seconds or for the length of the entire red light. Like I said, its sporadic.
But why would a clogged EGR valve be sporadic?
I understand what you mean by harmonics and that I may be sensitive to the torsional vibration if the mounts are worn in any way, but same question applies to the engine mounts .. why wouldn’t it occur every red light?
What I am thinking it could be is the fan .. doesn’t that turn on and off according to engine temperature etc?The engine PCM turns the EGR valve on and off depending on a number of conditions and inputs to the PCM. EGR should not flow at idle because of the degradation it causes of the idle quality. Basically it will choke the engine out if EGR flows at idle. Off idle the PCM will turn the EGR on. If the valve is dirty it can stick open and cause egr flow when it shouldn’t. Your EGR valve is electronically controlled and has a sensor that tlls the PCM the position of the pintle in the egr valve. If this were occurring it should set a code but i guess anything is possible. you can try pulling the valve and cleaning the pintle and seat and seeing if that helps.
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