Projectg2i

Running a B16A and a Chipped P28 ecu. Was running a stock PR4 for a while and a APEXi Turbo Timer w/ an AFM. Everything looked good and my voltage on the O2 sensor w/ the PR4 ecu was alway within spec and under .9volts. With the P28, the O2 sensor never gets under 4.45 volts, in perspective, thats about a 3:1 AF ratio. After the motor is warmed up and has been idle for about 25 minutes, I still get tons of vapor from the exhaust. Rap the motor up a couple of times and it will blackin the garage floor with carbon from the exhaust. I understand that I'm running way to rich and this is probably a P.O.S. chipped ecu, but is a 4.45volt reading from the O2 even possible or is there a new pin-out for the ecu although its still OBD-1 and uses the same harness??? Any ideas....please post.
Also, the ecu was purchased through APEX-R in Tucson, AZ (big mistake) and chipped from Arizona Race & Machine.

b19coupe

You have a problem. O2 sensor voltage should never exceed 1.0 volts. Sounds like you have a pinout problem with your ECU and your O2 sensor is getting reference voltage from the ECU (5.0 volts).

Projectg2i

Problem is, everything works very well if I stick the PR4 back in. There is no reason that I can find that a pin layout would change for the same wiring harness. I understand what you are saying about voltage. The O2 sesor always starts at 4.5 volts cold. After a brief amount of time, it falls into range when it starts to warm. This is normal operation. On this P28 ecu, it warms and falls to 4.45-4.41 volts. Makes no sense.

b19coupe

Are the pinouts the same for a P28 and a PR4 (not the wiring harness) ? O2 sensor voltage should never exceed 1.0 volts.

Projectg2i

It shouldn't go beyond 1volt, but it does when cold(before warmed up-standard for O2's). It shouldn't while under normal operation.

tinkerbell

um, dunno if this is strictly true.

zirconia o2 sensors will never read more than 1v.

ever.

but i might be worng.

i think you got a pin out problem.

t..

kenji

The O2 signal wire pin location is the same for ALL '92-'95 ECUs (D14).

Make sure you are checking the right wire.

-kenji