I have been told that the cause of black smoke on my 1993 Honda Civic could be due to the O2 sensor. I called the shops who informed me they have a 4 wire universal sensor that I would need to modify if I have a single wire O2 sensor.

I heard that there are 2 sensors on my car, where is the other one located and which of the two sensors play the part in the fuel/air mixture of my carby? That way, I will just change that one.

Here is a pic of my O2 sensor. Can someone please confirm if this is the O2 sensor and whether I am correct in saying that it is a single wire type??


Also the single wire runs to a connector mounted on the engine and then that connector runs to another connector that is mounted to the engine all by single wire. I presume it was to extend the wire since it doesn't look like its done for any other purpose.


How many types of O2 sensors are there and what should I get? Should I just buy any of should I try to locate a single wire, if it is possible??

What exaclty are the tools I need to perform this change?

 

You're leaking coolant... Check ECU for codes before doing anything.

Usually a bad O2 sensor won't cause such a severe change in mixture that there is smoking. I'd check fuel pressure with a gauge, make sure the vacuum line is connected to the fuel pressure regulator, get rid of aftermarket "performance" fuel pressure regulator. Check for ebay "chip" connected to IAT sensor and remove if present. Take out the spark plugs and if only one of them is black there is probably a problem with that cylinder's fuel injector.

There is only one O2 sensor on OBD1 models... I thought all 92 to 95 used 4 wire sensor, someone may have been there before, should be a 4 wire plug under the distributor.

 

Thanks.

I am trying to find where the Diagnostic connector is on my other forum thread so I can find the error codes.

The car just had a major service(oil, fuel, filter, spark plugs change, tune up) by mechanics a few days ago and the mechanic didn't even know it was computer controlled and wanted to adjust my valves and possibly drill it out or make it bigger to fix the fuel mixture problem. I told him, I had the heads replaced a year ago but he insisted that the tappets need adjustment in order to fix the black smoke problem. He didnt even check for error codes.

Il try and find this diagnostic connector so I can check the error codes.

Any other suggestions or reasons this could be happening by the way?

 

Oh, you're the one with the computer controlled carb (starting new threads about the same problem). That's going to be different...

Valve adjustment is something that should be done routinely but it's not going to cause smoke. Symptoms of being out of adjustment are excessive noise (too loose) or rough starting / idling (too tight).

 

MK (and poster). My 02 sensor on 93 civic was one wire.

Ed
Dallas, Tx

 

I was considering putting it all in one thread, but it didn't make sense to me cause my first thread was how to locate the diagnostic connector and this thread is about the O2 sensor. So if I put both all in one thread, it would be difficult for people to search incase all they want to know is how to find the diagnostic connector or find info about the O2 sensor.

But you are right, it basically boils down to the black smoke of my car with computer carby.

Thanks for the responses so far!

 

O.K. I have replaced the O2 sensor. I have noticed a great improvement on how it sounds and drives though it was very very rough when I first installed the new O2 sensor, but now it sound pretty good after 80klms.

There is heaps of black smoke when I first start the car and only when I start driving and the engine is warmed up does the black smoke eventually disappear.

I am hoping that maybe after 100klms that the black smoke on start up will disappear. Do you think there are other possible issues with the car that could be causing it to blow black smoke at the start?

A friend said to me, it could be the sticky choke that is causing the problem, but then I thought, wouldn't it blow black smoke all the time, since the choke sticks at high revs through out? My car currently idles at 1900-2100rpm and looks like the choke is on, when I look in the hood. If I am lucky, it might idle at 1400.

I am hoping that it improves on my overall fuel consumption. Originally it gave me about 520-550klms on a full tank. When I had the black smoke issue all the time, my car was only giving me 300klms.

Any advice?