Hi All,

I own a 89 CRX with a DOHC ZC OBD0 setup. recently did a restoration where the headers were replaced with aftermarket ones. Have been failing my emission test since. the mechanic narrowed it down to a missing o2 sensor, making it run rich.

however, my previous header had no o2 sensor (or so the restoration guy says), also the o2 sensor (single wire) is brown on my ECU end, whereas its grey on most forums. can that be a possibility, can my car be a model without an o2 sensor? or is the brown wire (ecu end) also existant?

 

Was the header the only work that was done? What ECU are you using? Is there a CEL (check engine light), specifically for the o2 fault code?

 

Yes just the header. The map sensor was detached after the paint, fixed it back up and the idle went back to normal.

Im using the pm7 ecu. No cel codes, no check engine light. Im stumped as well. Figured it was the o2 sensor cuz the car was running very rich.

 

The O2 is a core part of the feedback loop for the ECU. If you are running without it, the engine is running poorly. Can't imagine you would not have noticed that previously.

 

So my ECU pinout in place of the o2 sensor is a brown wire, wheras i i read everywhere it being white.

Is that possible?

 

Here is a pic of the old header. There seems to be no place the o2 sensor was plugged into.

Unless it was at the bent portion (which is missing now)

Is it at the bent area?

 

 

is this engine a JDM DOHC ZC or is it a DOHC D16A9?