I own a civic 2005 (as can be seen on my profile as well). I have been facing an issue since last winter. The issue is that when I start the car for the first time in the morning, its rpm doesn't stabilize for around 3-4 km of driving. Well to be precise, when I slow down the car for the speed bumps/breakers, the rpm suddenly drops and the engine turns off. After driving for about 3-4 km (sometimes more) the car returns to perfect condition and the rpm stabilizes perfectly. The condition worsens in winters where it can take up to 25-30 minutes for the car to become normal. Also, starting the car and waiting in idle till the temp gauge rises doesn't help much either.
My first guess was that the auto choke or the temperature sensor might be at fault. So I went to a mechanic and got those replaced. However no positive result was gained so I reverted back to my originals. The mechanic suggested that changing the complete throttle body (because it has all the sensors) might remove the issue. So I went ahead and did that as well, but no luck here either .
Once upon a time back in 2005-06, CNG had been installed and later removed after about a year from the car. My second instinct was to check whether those wires were properly connected as they might be the culprit to my problems. But still in vain as no issue was found there either.
I would request any PWer who has had that issue and resolved it; to come forward and help out a brother in need. Also, advice from senior members would also be much appreciated.
Thanks in advance guys.