bdadmiral

Hi,
I bought an 88 Civic STD on October 2013. Previous owner got it to pass smog but when I bought it, the cel was on and he told me it was the main relay which I replaced. I checked the ecu and its one flash from the light under the passenger carpet which supposedly is oxygen content. I've replaced the o2 sensor, spark plugs(which were black)+wires, and rotor but still threw the cel. I sold it a few weeks ago and owner can't pass smog because it is running rich + the cel, and is pretty much putting it on me to resolve the issue.

Here is a list of what has been replaced/done :
-02 sensor
-Main relay
-Spark plugs and wires
-rotor
-Exhaust manifold from another d15b1
-seafoamed
-carb cleaner sprayed down intake

Symptoms are
-hunting idle
-Bad mpg, 25-30 when supposedly it runs 40
-Black deposit on spark plugs
-Carbon deposit on tail pipe according to smog technician

What else could be causing the car to run rich? Ecu is only throwing oxygen content cel.

Please help, this issue has been causing me so much sleepless nights...

David_S

Fix the IACV which will hopefully solve the hunting issue. Check and make sure there are no cracks in the vacuum lines. I would not move on to the O2 sensor until the hunting issue was resolved.
Its running rich because the computer sees something wrong and has entered a default mode to keep from destroying the engine. Running a car too lean can destroy the valves etc. It makes the engine run hotter. I have lots of experience with this in the air-cooled VW world. Run those things hot for a little while and you got a big paper wieght.
And I believe some carb cleaners can kill an O2 sensor.


Did you offer him any warranty when you sold him the car? How old does a car have to be before you no longer have to get an emissions test? Here in Texas it is 24 years old.

bdadmiral

Alright, cleaned the IACV and burped the cooling system. No more hunting but cel still comes on. Still one flash. Do you believe I should try to replace the o2 sensor again since I used carb cleaner and seafoam after I replaced it?

I did not offer him any warranty but I was just made aware that in CA, seller is responsible for smog. If the buyer does the smog tests and it fails, the pink slip is void.