1989 civic DX d15z1/Hf tranny

[cbaber]

You've got the right sensor, and the right ECU. It's the wiring. The stock harness for that car didn't have 5 wires for the O2 sensor. The OBD0>>OBD1 jumper harness you bought probably isn't designed for a 5 wire O2 sensor either. Find a service manual pinout for the P07 ECU, and find where the 5 wires from the O2 sensor connect. Check continuity from the O2 sensor connector (engine bay) to the ECU connector. Do this for all 5 O2 wires, and make sure all wires are going to the correct pins on the ECU.

[Ryland]

Did you try unplugging the o2 sensor to see if it would run better without it, mileage should be better then 35mpg with the ecu running in open loop.
Only thing that I've seen that would kill an o2 sensor on a VX engine was over size exhaust.

[nitebluesky]

Funny thing this set up worked over the summer. When the weather was hot the asphalt with hot and my o2 never came on. Now that the weather is getting colder the ground is getting colder my o2 has come on more often now pretty much all the time.I don't have a big exhaust but I do have headers on it because the card didn't come with a cat near the engine. I know that the Honda Civic vx comes with two catsconverters. I don't have the one that's in front of the engine and that one is pretty expensive along with the 02 sensor. Its pretty much stock after my header.

[nitebluesky]

Mechanic did that on the testing and we couldnt figure it out. all I could think of is that it doesn't have a second Cat converter, but that cat near the engine is expensive.

[nitebluesky]

Here are my pictures of my engine bay. My 02 sensor; hf to my d15z1 and header.

[cbaber]

Now that you say the code wasn't present before, I would say the O2 sensor is bad. You said it was brand new, but how new? Why did you replace it to begin with?

[nitebluesky]

I got a code 48. O2 sensor is only two months old. I didn't replace it it didn't come with the motor when I bought it. My guess is the heat sensor. I've read that these sensors need to be really hot.

[Ryland]

Originally Posted by nitebluesky

I know that the Honda Civic vx comes with two catsconverters. I don't have the one that's in front of the engine and that one is pretty expensive along with the 02 sensor. Its pretty much stock after my header.

The VX only came with one catalytic converter and the o2 sensor goes right on top of it, about 3" from the head, the header you have is most likely causing the exhaust pulses to just pound that o2 sensor to death, it's not tuned for a engine that size that is turning that slow, they are a sensitive o2 sensor that doesn't last long with over sized or leaky exhaust.

[nitebluesky]

You are right on the pounding of the 02. I pulled it out I don't want to destroy it. Mine car is suppose to look like this guys. 1/3 way down I need that cat for sure. Crxmpg.com. I've got a lot of hestation in my probably explains the headers. I moved my 02 earlier to the back side of the engine near the original cat that came on the car. I drove around 15-20 miles and turned it off than turned my car on and my 02 didn't come on, but game me a code 48. SO from what you are telling me is that the header with high flow the 02 doesn't like it near or far unless near a cat where the air is slightly resisted by the cat but moving fast enough that the 02 throws a code 48. Hmmm.

[Ryland]

Originally Posted by nitebluesky

SO from what you are telling me is that the header with high flow the 02 doesn't like it near or far unless near a cat where the air is slightly resisted by the cat but moving fast enough that the 02 throws a code 48. Hmmm.

It's not so much that the header you have has a "high flow" but that it has to much of a pulsed flow and when you let a gas enter to large of a pipe to suddenly it cools and it doesn't flow as well, so it could be that your o2 sensor is constantly using the heater to keep it warm or it could be that the exhaust pulses are to violent in the over sized pipe and is just rattling it to death.
Either way, I bet that if you replace the o2 sensor it will last a few months again before giving up until you fix your exhaust.