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Discussion Starter · #1 · (Edited)
For the purposes of this question, the only difference between the 2 cars being compared, should be the year:
'94 1A2 vs '95 1A2
'94 V92 vs '95 V92
'94 WX3 vs '95 WX3
'94 9C1-LT1 vs '95 9C1-LT1
'94 V4P vs '95 V4P

(besides pwm)

Or put another way, any important differences between:
a '94 B-LT1 vs a '95 B-LT1
a '94 4L60E vs a '95 4L60E [nevermind pwm]

There is a reason why I'm asking what appears to be a hardware question in the pcm programming subforum …
Other than running changes like springs and fluid handling for harshness and longevity in the trans coupled with changes in calibration for the same,
I can't recall anything significant.
Its not uncommon for those kinds of running changes to occur. I see it quite a bit.
There were connecting rod differences, knock calibration differences, 94's supposedly had different cam lobes/timing, but not enough to matter. I have heard of, but not found forged rods in 94's as well.

What did you notice?
Between '94 & '95, seems there are more differences in the software, than in the hardware.
Just as an example [among several], you mention knock calibration differences … that do not necessarily correspond to hardware changes (they even share the same knock module).
Guess it made sense to GM? Doesn't really make sense to me.

Maybe they were just saving themselves work …
is there a way to see if the particular pcm shows a software version number and compare to others?
Don't know if this answers your question:
CHUGGLE OR SURGE AND AN INTERMITTENT DTC 32 #57-65-17A said:
Year … Cal ID # …… Gear …… Application …… Emissions

1994 … 16239501 … 3.42 … 7K Tow-V4P … Fed/Cali
1994 … 16242991 … 3.08 … Police ~ 9C1 … Fed/Cali
1994 … 16243001 … 3.08 … 9C1 but VZ2 … Fed/Cali
1994 … 16243011 … 3.08 … ImpSS~WX3 … Fed/Cali
1994 … 16230221 … 2.93 … 5K Tow~V92 … Fed/Cali
1994 … 16230211 … 2.93 … B- / D- Body … Fed/Cali
1994 … 16243931 … 2.56 … PubServ-1A2 … Germany
1994 … 16230201 … 2.56 … B- / D- body … Fed/Cali

1995 … 16239511 … 3.42 … 7K Tow-V4P … Fed/Cali
1995 … 16243021 … 3.08 … Police ~ 9C1 … Fed/Cali
1995 … 16243031 … 3.08 … 9C1 but VZ2 … Fed/Cali
1995 … 16243041 … 3.08 … ImpSS~WX3 … Fed/Cali
1995 … 16243171 … 2.93 … 5K Tow~V92 … Fed/Cali
1995 … 16243181 … 2.93 … B- / D- Body … Fed/Cali
1995 … 16243941 … 2.56 … PubServ-1A2 … Fed/Cali
1995 … 16230251 … 2.56 … B- / D- body … Fed/Cali
Stick any B- or D-car VIN you like into GM SPS Info, those are the part numbers for the calibration IDs that pertain to each application. (It actually says 'Germany'. Try it yourself!)
why I ask is that they may have incorporated updated software versions as cars were built, to provide better drivability and emissions.
I'm sure they did that … for the '95s.
Why not the '94s?
(Where's Katshot?)
I do at work a lot of what they call ecm recalibrations for cummins, international, isuzu and detroit.
the diesel engine oems are always updating the software to prevent phantom fault codes and better emissions. I've seen some engine models with over 40 update versions.
For two model years that share very nearly the exact same hardware, how different are the calibrations?

Basically, there should only be one thing to differentiate a '95 calibration vs a '94 calibration: pwm, the only major hardware difference … except it is not the only difference.
Despite being identical [apart from pwm], the calibrations are admittedly close, yet obviously different enough that I checked with you guys to see if '94 hardware was meaningfully different from '95.
 

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Other than running changes like springs and fluid handling for harshness and longevity in the trans coupled with changes in calibration for the same, I cant recall anything significant. Its not uncommon for those kinds of running changes to ocurr. I see it quite a bit.

There were connecting rod differences, knock calibration differences, the 94's supposedly had different cam lobes/timing, but not enough to matter. I have heard of, but not found forged rods in 94's as well.

What did you notice?

Chris
 

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is there a way to see if the particular pcm shows a software version number and compare to others?

why I ask is that they may have incorporated updated software versions as cars were built, to provide better drivability and emissions.

I do at work alot of what they call ecm recalibrations for cummins, international, isuzu and detroit.
the diesel engine oems are alway updating the software to prevent phantom fault codes and better emissions, Ive seen some engine models with over 40 update versions.
 

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Don't know if this answers your question:Stick any B- or D-car VIN you like into GM SPS Info, those are the part numbers for the calibration IDs that pertain to each application. (It actually says 'Germany'. Try it yourself!)
I'm sure they did that … for the '95s.
Why not the '94s?
(Where's Katshot?)For two model years that share very nearly the exact same hardware, how different are the calibrations?

Basically, there should only be one thing to differentiate a '95 calibration vs a '94 calibration: pwm, the only major hardware difference … except it is not the only difference.
Despite being identical [apart from pwm], the calibrations are admittedly close, yet obviously different enough that I checked with you guys to see if '94 hardware was meaningfully different from '95.
ok the website does refer to calibrations, I'm guessing you would input the vin, get the latest calibration number and compare to whats on the pcm to see if its the latest.
looks like they change the whole number for a updated version instead of using a suffix i.e. like .1 or .2 etc.

but as to specific changes, none of the truck oem's will tell you the specific changes as its inbedded in the code and they do not want anybody mucking around with that.
what most do say is what features or fault codes the changes address in that particular calibration.

as far as differences between years I've done so many I've lost count, I did notice two different cummins CNG engines about the same year of manufacture (2012) had different calibration part numbers.
both were in freightliner M2 tractors with same specs so who knows cwm3
 
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