Pliskins

Hey.
So I own a Honda Civic 96 1.4 Fastback. Recently I encountered issue when I start my car the RPMs were bouncing up and down. When I accelerated gas a bit (to 2k RPM) and released the pedal engine almost died. It was happening for like 2-3 minutes then it satled down and everything was fine again when it got heated up a bit. So there might be some issues with cilinders or spark plugs. I want to go and get diagnosys at service. I don't know where and if I have OBD connector. If I have, where should it be? I was doing a quick peek under steering wheel near pedals, checked to the middle part, didn't see any free connector. Then did check from passenger side to middle of the car. Didn't see any connector. Steering wheel is on the left side of car. Not the UK variant if that changes anything. :D
All I know that I have some connector at passenger side near doors under the dash, I can pull out 4 + 2 pin wire. I know that 2 pin connector is for Airbag, I was reading code with it and paper clip. But I have no idea what is the 4 pin connector for.

So the main question - does 1996 Honda Civic 1.4 66kW Fastback had OBD connector? And where can I find it?

mk378

I don't know about the European models. 1996 was the first year OBDII was in the USA models. The earlier USA models with OBD1 would blink codes on the CEL when the 2-pin jumper was jumped. That same jumper would also activate the diagnostics in the SRS and ABS (if equipped) computers.

Anytime there is uneven idling but the car drives OK, the primary things to check are dirty IACV (officially the EACV), cooling system not full, throttle body dirty or throttle cable sticking, and vacuum leaks.

Pliskins

So I should be able to do diagnosys with the same 2 pin and paper clip? Because I tried that (found in google that you should be able to do it with just paper clip) for like 30 secs and any of panel lights were not flashing. All were just turned on and nothing happens.

Car is not driving OK when the RPM are bouncing, you can feel the power loss during driving aswell, but when everything satles down there are no power loss spikes and even idling is ok. It happens only when I start my car in the morning or after half day the same day. Maybe something with cold weather aswell? As it is starting to freeze here. Winter is coming, actually it is here already.

mk378

If you have OBD1, with the jumper in and the key on (not started), the CEL will either flash out codes or stay on steady if there are no codes. If the CEL never comes on while driving with the jumper out, there probably are no codes.

Pliskins

Never saw CEL turning on during driving. Only light that flashes is the oil because my car really likes oil. Have to fill it a bit from time to time. Will try to use jumper later again for a bit longer time.

Maybe it is something with IACV or the other parts. This summer my cars temperature was going up like crazy but only when driving in cities. Mostly in rush hours when you have to stand a lot and move only few meters in some minutes. I brought my car to service they were checking the cooling system, and they said everything is working currectly, the fan starting up when it gets too hot. But the tempereture needle never went up at service. So I suppose the speedometer is just showing wrong or the sensor (dunno how to call it, thermostat maybe) is bit messed up. But the important thing to tell which might be related to IACV, when I was driving in summer, the car was lacking some power each time I was starting to move. Didn't have AC turned on so I don't know why there was power loss on low RPM when starting to move from standing position.
​​​​​Don't know about throttle body or cable nor vacuum leaks. Haven't checked them.

Pliskins

It was silly how temperature went down from max to normal (to like 2/5) when i could get to drive faster than in city, in like 2-3 seconds so the cooling is fine just the needle is not showing right.

mk378

Park on level ground or with the front of the car uphill and wait until the engine is completely cold. Then check the coolant level in the radiator. Don't just check the white plastic tank, open up the radiator. It should be full to the top. Lack of coolant causes uneven idling and overheating.

Pliskins

Oh the white tank was sometimes going over max mark, meaning the coolant frorm radiator comes to the tank. I was surprised that the tank has only one exit and same entrance rubber pipe. Was thinging that circulation might be clogged or something but if the coolant is not going trought tank I don't know how can it get over max mark. But the idling is fine after 2-3 minutes. Static RPM, just the first time I start the engine. (Did't happen this morning, but did happen last 2 mornings).

mk378

Since the radiator and engine are normally completely full of coolant, the plastic tank is there to receive coolant as it warms up and expands. When the engine cools, it is supposed to return to the radiator. When the plastic tank overflows and the coolant doesn't return, that usually is because the head gasket is leaking, filling the engine with air and exhaust gas that displaces the coolant. Sometimes though it is just a bad seal in the radiator cap.

This, and the oil light coming on, are serious problems that need to be dealt with before you bother with the idling.