First time posting. Got an intermittent low and rough idle on my 2007 Honda Civic LX. Will generally only idle low and rough for a stop light or 2 then things will relatively go back to normal. I've replaced most things that could be causing this which have each helped in there own way solving various problems and have helped with overall engine performance but it still has a few hiccups here and there.

Engine will also randomly develop a rhythmic pulsing with 1-2 second intervals that can only be felt, rpms do not change but it feels as though the ecu is adjusting idle/ fuel mixture to account for a fault somewhere. This generally only lasts for a stop light.

Any help is appreciated! Parts replaced;

MAF, MAP, purge control solenoid, spark plugs, PCV, fuel injectors (leaking, long crank time without priming, oil smelled heavily of fuel), fuel filter/pressure regulator, and probably a few other things.

Have attempted ECU reset and idle relearn but part of me feels I'm not doing the ECU reset correctly so it's still accounting for a fault the used to be present.

  • To teach idle to your ECU and PCM, start it, hold on to 3000 RPM until you hear the radiator fan cycle, now let go of the accelerator and let it sit idle for 5 minutes. Mission accomplished. (All electronics must be turned off prior to this procedure) Check for ignition coil status, fuel regulator, and fuel rail. Inspect for further intake and exhaust leaks, especially around gaskets. Run a scanner to read live fuel readings. Share them here. – Numair Aidroos Sep 24 '17 at 15:26
  • See though I feel like there should be more to help the ecu relearn it's parameters. But anyways, I've done the idle relearn correctly then. What do you do mean by ignition coil status? When you say fuel rail do you mean check the fuel pressure? I checked pressure about a month ago and it was bouncing around but within spec so I replaced the fuel pressure regulator, haven't checked it since. Maybe I should check it again as well as while driving around. I will post fuel trims when I get a chance to look at them – bryanstevens314 Sep 24 '17 at 17:44
  • Now if you did the idle procedure correct, RPM should not bounce off the charts. Go to Honda, they'll connect the HDE HIM Honda scanner and program it. And yes check the live fuel ratin – Numair Aidroos Sep 24 '17 at 17:57
  • Check the fuel live readings. And condition of the ignition coils, inspect around all intake and exhaust gaskets and hoses. – Numair Aidroos Sep 24 '17 at 18:07

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