Where is the O2 sensor supposed to be located for a ZC in a 1990 CRX. I bought the car with the motor already in the car and the O2 sensor is in the rear of the header near the cat. My car is running really rich and is bogging after it runs for a while. When you start the car it runs fine until it warms up, then it bogs. I've already changed the O2 sensor cause it threw a code and now its not throwing a code but it still runs rich and bogs. Is it the placement of the O2 sensor, that is causing the problem?

 

Could be a faulty new O2 sensor?.. ( I doubt it)
I do believe the 02 sensor is in the correct location? ( a little help if i'm incorrect)
Coolant Temp sensor will make the car run rich and not throw a code..
I have seen resistors added into the coolant temp circuit to throw off the ecu w/ success, but I would use that method as a last resort..
Definately check the coolant temp sensor and 02 sensor values w/ a DVOM..

 

Where is the coolant temperature sensor?

 

lil' clear plug 2 pin connector on the passenger side of the intake manifold.. don't know the colors offhand..and the thermal switch and sensor are close by, so try not to confuse them.. wish I could be of more help..

 

On the back of the motor? I always thought that the temperature sensor was the one prong connector that was on the passenger side of the cylinder head, near the bottom of the head.

 

yea- the TW sensor is under the distributor on the pass. side of the head. The one prong sensor is the sending unit for the temp guage.

 

uhm, yeah. on the side of the head, thats what I meant

TW sensor resistance should be approx 200-400 ohms with the car warmed up to normal operating temp..

You also have the symptoms a stuck fuel injector that would make the car run rich and throw an 02 sensor code.. might be something to think about..

 

I checked the plugs and the are all black (rich). Had the car on a dyno yesterday and the headers started glowing red. It was freaky. But I switched the Headers for an old stock 1.5L manifold with the O2 sensor in the upper part of the manifold near the cylinder head and the car runs alot better and doesn't bog anymore. Thanks guys for the help!!!