The car drives WAY better, smoother and more powerful and gone is the stutters after replacing the 80k old original stuff... But bad idle remains. Any ideas? Idle just shoots up and down, goes up, starts slipping, then falls almost dead and the engine abruptly picks it up, then it just does that on and on. I'll take a video in the morning and post it up, although I think everyone knoes what it's like Honda needs to seriously figure out what the actual cause of this is, and stop ignoring us or sending us on the runaround. It's getting old

 

I noticed smoother idling right after installing a new set of plugs (Denso IK22s set at a .032" gap). Before getting new plugs however, I would just try closing the gap down first, to see if that helps.

 

Have you tried going the alternator route?

 

Could it be a problem with the IACV (Idle Air Control Valve) on the throttle body?
I once started my Civic with the IACV plug removed. The car didn't idle at all well. Revs would rise then drop, rise then drop etc...
Maybe you could pull the plug on the valve to see if it gets worse? If nothing changes, that may be the cause.

 

Have you done an idle relearn?
Let the car sit over night.
Unhook the battery.
Discharge battery thru brake pumping and maybe wait 10 min.
Hook up battery.
Do not at any point touch the throttle.
Start the car.
Let it run for 20-25 minutes.
Fans should kick on.
Turn car off.
Restart as normal.

My S was having a weird idle issue and was surging and dying after work that was unrelated. Did the idle relearn and poof. Back to normal.

 

Have you adjusted the valves?

 

I had IK22s installed about 10k miles ago

No valve adjustment yet, I tried letting the car run and figure itself out, but I'll try doing it again.

Someone just suggested checking an idle valve so Im gonna run to my car and see if I can find it right now

 

it appears to be smoothing itself out... we'll see how it goes

 

That's cause the ECU is finally learning the idle.

Put a quick end to your misery. Do the Idle Learn as Btrthnezr3 said. It's worth the 20 minutes.

One additional step: The factory manuals always say to turn the ignition to the RUN position (engine off) for at least two seconds before starting the engine.


PS If you have the factory radio make sure you have the Access Code so you can re-program it after you disconnect the battery.

 

Dirty throttle body can cause a rough idle. Clean the throttle body and adjust the valves.

 

^ it should either be that or a bad 02 sensor.. I have a greddy turbo kit installed so I think oil is being blown around everywhere and getting on stuff

 

Please try idle relearn too.

 

Check the fast idle circuit, both computger and idle screw. usually the idle shoulfd be about 1500 til the engine warms some.

 

If you have OBD ll checker check diagnostics for P0506 code. Dealer will have to follow the manual.