I've been looking at a couple of '95's and '96's and would like to know what the differences are in the ECM's. I believe 95 is an OBD-I and '96 is an OBD-II. What's the differences in what they control and what is the pros and cons in their adaptability and ease in custom programming?

Let me rephrase the question. Are there any disadvantages one over the other ('95 OBD-I and '96 OBD-II) when it comes to performance programming, other than possible software costs? I've heard somewhere that some guys try to retrofit back to the '95 system, but I don't know if that's true or just an urban myth. Thanks

 

Please forgive me if I am mistaken (someone will no doubt correct me) but I believe both 94 and 95 (LT1's) are OBD2.

But to answer your question, the difference between ODB1 and 2 is that technology marches on. ODB2 can be flashed where ODB1 needs to have a chip burned to change the tables - well, except now we have the Ostrich to get around that ODB2 does more, is faster, can monitor more stuff, has more diagnotics, yadda, yadda, yadda...

 

Nope, both 94 and 95 are OBDI and needs to be flash tuned, no chips.

Tuning on a 95 and 96 will be pretty much be the same. But, the 95 tuning software is considerably cheaper.

 

ttt for question update

 

You also can just use a jumper wire to retrieve the codes on the OBDI.
My vette is a 95 OBDI my other vehicles are OBDII
I think the OBDII is easier just because I have a OBDII code reader

 

I've tuned both and the only difference that really mattered was the OBD2 computer has alot more trouble codes and monitoring. It was harder to trick the computer into not setting codes when performance enhancements were made.

The price for tuning software is the reason most people opt for OBD1

 

Both are OBDI systems but I think the ALDL connectors are the OBDII style. All cars built after Jan 1, 1996 had OBDII.

 

Yes 94/95's had an OBDII ALDL, which makes it a little hard with code readers.

 

OK, let me get this straight...94/95 are OBD-I in a case that has OBD-II connections. 96 is a true OBD-II ECM....I'm getting so confused

 

Yes.

 

Not too confusing. Some manufacturers started using OBDII in 94. GM most likely decided to go with the 16-pin OBDII connector in anticipation of the upcoming requirement for OBDII.

 

Is it fair to say that everything else being equal, if your're headed toward modifications, a '95 ECM is easier/better to work with than the '96?

 

In my opinion the 1996 OBDII is easier to work with because it is not as prone to locking up as the 1994 and 1995 OBDI computer. I have never had a 1996 OBDII computer lockup on me when I was programing. On the other hand I have had the OBD1 compuers lockup while programing which requires you to remove the internal chip and get a new one or send the computer in to have a new chip installed. Either situation is a pain to deal with and takes time to complete.

When I am programming 1994 and 1995 OBD1 computers I always feel relieved when the tuning job is complete without any lockup issues. The 1996 OBDII computer does not have this issue.

 

Here's some stuff I came across. I could pretend that I know all this stuff, but I "ain't" that smart, LOL

The 94-95 LT1 Corvettes used essentially the same PCM, but with one additrional microchip to begin OBD-II like communications. The Vette controller used service code 16181333.

In 1996, the mandated arrival of second generation on-board diagnosics (OBD-II) was the notable news. The LT1 PCM for 96 was similar in architecture to its predecessor but featured a faster 6800 series processor and a doubling of one memory chip's size - for a total combined flash memory of 192 kilobytes. The service code for the 96 was 16214399

The 1997 module was practically a carryover and is interchangeable with the 1996 modules, but has a new service code 16242921.

Jake

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The 1996 LT4 Corvettes also featured a relaxed knock module which enabled more aggressive spark advance. GM identifies it with part number 16214681 Other differences between the LT1 and LT4 controllers ae limited to calibration.