legacycentral bbs

First off, does anyone know how much more info if any, the ODB-II from like a second gen legacy takes than the ODB-I's in our cars? Next, how much stuff would I have to replace in order to get the ODB-II to work in a first gen. I'm thinkin relays and some sensors mainly, maybe a new ECM? And finally would changing all this really mess up my car? I have a feeling that there will be incompatablities between the ECM from the two cars, like fuel mixtures and stuff like that.

As for more info, basically there are two pieces of information OBD-II ECUs collect that OBD-I ECUs don't: rear oxygen sensor signals, and misfires.

OBD-II cars have an extra oxygen sensor after the catalytic converter. Its only real use is to monitor catalyst efficiency.

The OBD-II ECUs also detect misfire; I believe they determine whether or not proper combustion happens by measuring crankshaft acceleration.

AT OBD-II ECUs and some later MT ones also have an external pressure sensor that measures manifold and ambient pressure using a pressure exchange solenoid.

You definitely would need a new ECU if you wanted OBD-II; the ECU is the heart of the whole system. If you used an EJ22 OBD-II ECU it might run well enough...

The ECU harness connectors are completely different, so you'd have to splice them in or make some kind of adapter.

You'd have to add the pressure sensor and exchange solenoid and the rear oxygen sensor. The radiator fan control is a little different so you may need some relays there. You'd have to wire in an OBD-II interface connector. The OBD-II ECU will want to talk to the TCU but of course can't since the BC/BF TCU doesn't talk to the ECU, so you'll need to somehow pacify it. The TPS signal is different so you'd need to use the newer sensor (which may require a newer throttle body and maybe manifold) or make a circuit to condition the signal. The IAC valve may also have different characteristics; I'm not so sure what you'd do about that other than using the newer valve and maybe manifold.

But, uh... why? The only thing you'd gain from alllllll that work would be that the ECU would tell you if it detected misfires if you hooked up a scantool.

Silly thawa its not odb its obd. Anyway, the main reason for wanting OBD-II is that it is standardized and as such much easier to interface with software, however I really don't think it's worth it now to have to do all that stuff. Cant find much on google so would you happen to know of someplace to find which pins on the OBDI connector do what?

What OBD-I connector? You mean the yellow Select Monitor connector? You might start here for a little info:

http://lillith.sk.tsukuba.ac.jp/~kashima/car/gc8-e.html

I believe your 1990 ECU's parameters will for the most part line up with the ones Kashima found.

Hahahah... ODB, whatever happened to that douchebag?

He got sent to jail, fat and just recently let out, i liked him because he seemed like he would be funny to just talk to like inperson or soemthing, not interesting to hold a converstation with and definately not a friend or someone to trust, too thuggish.

He gets points from me for interrupting an otherwise boring and pointless Grammy Awards ceremony a few years back.

Steve