What are the differences between OBDI and OBDII?

I know there is no second O2 sensor on OBDI, as well as EVAP differences about when it opens. What else? (Aside from it can be chipped, blah blah.)

Real differences. Thanks.

 

OBD2 adds:

O2 after catalyst
Crank fluctuation sensor to check for misfires
different ecu architechture
OBD2B has fuel tank pressure sensor

not much else that i can think of

 

Thanks Steve.

 

...and to add
Most US integra 99-01 OBD2(b) ecu's have an immobilizer for added security in regards to the the key & ignition.

For JDM OBD2 ecu's, in a sense, its like OBD1 programming on OBD2 hardware. They look for all of the same sensors as an OBD1 ecu and none of the extra sensors like its US counterpart.....aand as an added bonus JDM OBD2 ecu's do not look for the vtec pressure switch as well.

 

Another important difference is that OBDII stores error codes even after the ECU power is disconnected. There is usually some complex procedure which must be carried out to clear the ECU. OBDI, on the other hand, loses any stored codes after the battery is disconnected.

 

[QUOTEFor JDM OBD2 ecu's, in a sense, its like OBD1 programming on OBD2 hardware. They look for all of the same sensors as an OBD1 ecu and none of the extra sensors like its US counterpart.....aand as an added bonus JDM OBD2 ecu's do not look for the vtec pressure switch as well.[/QUOTE]

Actually, from what I have heard, the whole OBDI and OBDII thing is strictly USDM. In Japan, there is no such thing as either. In effect, all JDM ECUs are 'non-OBD'. By the way, there is no such thing as 'non-OBD' or 'OBD0' here in the states. The 1988-1991 ECUs that everybody refers to as 'non-OBD' or 'OBD0' actually use an earlier version of OBDI.

 

I've heard something like that also....
but everyones so use to seeing the differences in ECU plugs its easier to categorize each wiring generation as nobd, obd1, obd2a, or obd2b....whether it be JDM or US.

 

Does OBD I, have Long Term Fule Trim (LTFT). I don't think it does so that would be another diff. But I'm not sure...

 

yes it does.

And I do not think the honda obd2 ecu is able to store codes if BACKUP power
is removed.