Ight my buddy has a 89 hatch with a d15b7 swap and ever since we had this engine in that car it throws o2 when the car warms up and runs like **** when it kicks in, im not dumb i know alot and we have had like 4 engines in that car that ran great but this one just throws the o2, we are still using his pm6 with a one wire o2, we have hard wired it to the ecu and the o2 is brand new the car is in time, burns fuel correctly i just dont know.

Any Suggestions On What We Should Attempt Next???

 

Anyone?

 

You can check these few...

Fuel pressure.
Crack in ex. manifold, or exhaust leak between head and manifold.
Do you get voltage at ECU's pin.(Back probing the connector)
Have you tried a different ECU.
Are injectors in good condition.
vacuum leak somewhere.

There's a few. You sound like you have some experience so I didn't go into detail. It can be a bad signal from the O2 sensor or the motor is running to lean/rich to correct and throwing the code.

If you have Q's get back to us.

 

There are no cracks anywhere, we are getting voltage, injectors are good and getting plenty of fuel pressure, and ECU is good we ran it with every other motor he had, and every other motor we had in the car never threw the o2 code so the only thing i can think of as far as leak would be the exhaust manifold gasket thats the only gasket we re-used?

 

you should be able to hear that exhaust leak so I'm leaning towards no.

What we do to check the ECU is unplug the sensor wire and the part that goes to the ECU we hold in our hand and touch the battery + and - with the other hand and watch the emissions go from rich to lean. Unfortunately you would need test equiptment.

I'll get back to you in a bit.

 

You said you hard wired the O2 sensor to the ECU? How did you hard wire it? Solder? Butt Connectors( )?