I HAVE A 98 EX CIVIC. THE ENG HAS STOCK INTERNALS. INTAKE /HEADERS/ 2.5 INCH PIPNG FROM THE HEADER TO THE MUFF WITH NO CONVERTER. I AM HAVING A PROBLEM WITH MY CAR RUNNING RICH. I NOT SURE IF ITS A 02 SENSOR OR ECU PROBLEM OR IF ITS A STUCK INJECTOR OR VALVE. JUST WANDERING IF ANYONE ELSE HAS HAD THIS PROBLEM OR KNOW WHERE TO START.

 

Is there any check engine light? If there is a check engine light that would be the place to start. I would check the fuel injectors just to make sure they are opening and closing. I think you can listen to the injectors to hear them opening and closing. You could also get this trigger thing that you point at the injector and it flashes a light whenever the injector opens.

 

I DO HAVE A MIL FOR CODE PO420 WICH IS CATALYST DETERATION. BUT ALSO KEEP IN MIND THAT I HAVE NO CATYLITIC CONVERTER ,HEADER AND 2.5 INCH PIPING BACK. I ALSO DID RESEARCH ON ALLDATA AND THEY SAID LOOSE TERMINALS ON THE DISTRBUTOR WILL ALSO CAUSE THIS CODE TO BE PRESENT IN THE ECU.

 

Please turn you caps lock off

 

So do you have an o2 sensor? You will run rich if you have a CEL. Hop do you know you are running rich?

 

yes i do have (2) o2 sensors. i know im running rich because there is a 1/4 inch of carbon on my bumper and i get about 250 miles per tank. im just wandering if this is a common problem with hondas or just mine

 

If you dont have a cat the ECU will think somthing is wrong because your 2nd O2 is gonna be the same reading as the first one. You need to get a 2nd 02 sensor device that fools the ECU into thinking that you still have a cat.

Berz out.

 

I don't think that a P0420 will cause your engine to run rich. That code pretty much just says your cat is bad/not doing anything. What is the voltage on the 1st O2 sensor? If the sensor is varies between 100mv to 600mv, then there isn't a problem. However, if the sensor is showing that there is always a lean mixture then that is a problem since the computer will try to richen the mixture by adding more fuel. If you can find a way to make the 2nd O2 sensor give a reading off 100mv then the code will go away, but since the O2 sensor isn't a passive sensor i don't think you can just throw a resistor across the terminals of the sensor.