My car blows black smoke, runs really bad and I have been told, it is due to the fuel mixture being incorrect.

I have a 93 civic that has computer controlled carby for the fuel mixture. The car was given a major service recently and it still continued to run bad. The mechanic told me it was the valves that need adjusting and resizing but I was a little hesitant to believe because I just had the heads replaced.

I realised that the mechanic didn't even know it was computer controlled carby and didn't even check the computer for error codes.

I decided to do some research and I read that you should reset the computer after a tune up. I reseted the computer and it now runs normal, once it gets to temparature, like 2/5 or halfway on the temparature guage. But before it gets to that temperature, the car blows black smoke, so I have to warm it up before it runs right.

I thought it could be the O2 sensors, like I read in other forums but if it was, wouldn't it blow black smoke all the time, or could it be that the sensors only run right once it reaches car temperature??

I have a friend who sais that you have to wait one or two fuel refills before the computer settings kick in and the mixture will run correct at all times when you reset the computer. Is there any truth to this?

Any advice on what it could be or what to look for?

Thanks

 

Fortunately we didn't have those in the USA. By 1993 they were all MPFI. So I'm just guessing here.

On the fuel injection, the O2 sensor is completely ignored until it is warmed up. Then it goes to "closed loop" operation. I suspect yours is the same. During open loop operation (before warm up) yours is probably going to use a remembered calibration from the last time it was warm. But it seems it may not be remembering properly. If you lose the back up power constant from the battery to the computer, the computer will reset every time you turn the key off.

Look for a "BACK UP" fuse in the fuse box under the hood. On the US models this fuse also supplies the radio. It is very common for it to get blown when someone is tinkering with the radio wiring.

 

I really hoped that this was the solution cause it completely makes sense but I checked it and the fuse is not broken and also the radio station and the clock holds their memory ok.

Is there any other reason as to why the computer could be off at startup? Could it be a temperature guage issue or could it be the computer? It be good if you could adjust it for startup!

 

Is the computer designed to report error codes? Find out how to read them. In that case you could check the memory function by disconnecting something to intentionally cause an error code, and see if the code is remembered like it should be while the key is off.

 

first things first. like the guy said above. check for codes... it is posible to be the o2 sensor.

 

O.K. I finally decided to try checking for the error codes after doing a long drive on the car and notice it change from a good start, to alot of black smoke when idling at traffic, to idling at 2300 rpm at standstill, to the idle pulsating slowly from 500-1800 on the odometer, to conking out when coming to a stop. All in a 80klm trip up and back.

I grabbed a copy of a service manual that stated to look for the 2P Service Check connector at the passenger side but I am unsure as to which cable it is referring to. I can see a connector that is connected to the chassis but I do not want to pull it out incase it is incorrect.

Does anyone know what colour cables I should be looking for, or any hint as to know how to identify the cable?

The area in the manual does not look like the area in my car. I am wondering if the cabling could be different in an Australian model since it is Right hand drive and judging by the pic on the manual, it is left hand drive.

Is there an Australian instruction somewhere online that people can recommend in regards to finding the Service Check Connector terminals??

Looking at the car symptoms I have now, besides the O2 sensor, could there be other common issues and solutions or other tests I can perform. I remember the mechanic saying there was something wrong with the choke, and that it gets stuck which I have noticed that the idle seems to get stuck at high sometimes where I have to turn the engine off if I am not moving.