Hello... I tried googling everywhere to clear my issue but I'd like someone to help me find a problem with my 2002 Civic LX.
Please have a read on my case and let me know what would be the problem causing this.

Problem:
1. Car starts fine when cold. After driving commute of 10-20 min, car idles around 2K-3K RPM while parked. When on D gear, car keeps accelerating around 30kph without me touching any pedals on 1K-1.5K RPM.
2. Car starts fine when cold. After fueling the car (half tank), struggles to start. When car is showing above problem, it's almost impossible to start the car. I noticed tonight that there's some fuel rolling down from fuel cap (probably from vapor?). Will swap fuel cap tmmrw.

Background:
Code P0118, P0128, P1457
The car has recently had: timing belt/water pump change, valve cover gasket replacement, throttle body cleaning, radiator and thermostat replacement, air filter and oil change.
Car's ODO is 363,000 Km.
The car had 3 overheats when the radiator was busted but not showing any head gasket leak- no exhaust colors.
Heating works excellent both stopped and moving.
Coolant temp gauge is not working recently, was working intermittently a week ago(Not 100% sure but I felt the idle was better when temp gauge was working).
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Planning to swap coolant temperature sensor and fuel cap tomorrow... Would ECT sensor actually affect idling like my case?

 

Well, I'll answer my own question...

I think it was ECT sensor that was doing all this. I unplugged it, heated the sensor up with a lighter and temp gauge risen up. So plugged it back in and idled 15 min to see it idling nice at 900 RPM with opt. temperature just below the middle.

I also got some screws from pick n pull to fill in the missing spot at air filter, tightened it to feel the acceleration power is a lot better too.
I couldn't observe fuel vapor leak from fuel cap today so I haven't changed it but car starts both hot and cold very well now.


Hope my case helps somebody else.

https://www.ericthecarguy.com/faq/so...e-idle-circuit
Check out this page, been a big help for me.

 

A bad coolant temp sensor made mine flood after it warmed up , you would go to start it and you'd have to wait a half hour , guess it didn't know it was warmed up . I;ll admit these cars can have their problems and spookyness but overall they're not bad .

 

Hi,
l have a Civic 1.6l 2004 Hatchback with 272k Petrol+LPG.
While driving in city 20-30km/h the rpm drop and tent to stall, sometimes it stalls. I try pushing the throttle during that moment but it doesn’t go higher than 2000 rpm. The same problem happens when l drive in petrol or LPG. Fuel pump is ok. Battery ok. Sparks ok. Oil and filters ok. I’ve noticed that once the engine is at the right operating temp. it works fine even on idle. So l experience rpm drop after l turn on the cold engine to lets say 20-25 min of driving.
Any suggestion is welcomed.