[align=center][:-]Below is information from `Space, he's attempting to learn about below [:-][/align][align=center]PCM Flash Reprograming[/align][align=center]
[/align][align=center][/align][align=center]Flash reprogramming PCMs is NOT for the feint of heart. It takes a considerable investment in equipment, paying OEM subscription fees to get flash updates on a CD or online, plowing though pages and pages of charts and tables and TSBs to figure out whether or not the calibration software in a vehicle's PCM needs to be updated, and then plunging ahead with the update itself[/align][align=center]Yet PCM flash reprogramming is becoming more and more necessary as vehicle modules get smarter and more complex. GeneralMotors estimates that they have released flash updates for as many as 70% of 1995 and newer GM vehicles.[/align][align=center][/align][align=center]PCM Programming is Nothing New[/align][align=center][/align][align=center]Would you believe flash reprogrammable PCMs have been in vehicles for more than a decade? The first such application was the 1990 Geo Storm. Why a humdrum car like the Storm would be the first to receive a flash reprogrammable computer system is unknown. You would think GM would have chosen a more high profile vehicle like a Cadillac or Corvette to usher in the new technology. But they didn't. The choice probably had more to do with production scheduling and new model introductions than profile or image. GM knew OBD II was coming and that it would require a new generation of PCMs that were faster, more capable and able to be programmed electronically.[/align][align=center][/align][align=center]Up to this point, Program Read Only Memory (PROM) chips held all of the PCMs vital calibration information and operating instructions. GM pioneered the replaceable PROM chip as a way of programming a limited number of basic PCMs to fit a wide range of GM makes and models. A replaceable PROM chip also meant the PCM could be "retuned" if necessary to correct certain kinds of emissions or driveability problems. It also meant that if a bug was later discovered in the original factory programming, it could be corrected in the field by simply replacing the original PROM with an updated corrected PROM (a tactic GM has successfully used over the years to fix many factory flaws). Performance enthusiasts also liked replaceable PROMs because the chip could be replaced with one that provided more spark advance, fuel enrichment, a higher rev limit, etc., to squeeze more power out of the engine.[/align][align=center][/align][align=center]But replaceable PROMS had a serious drawback: there were too many of them! Every model year and every running change meant another PROM had to be created. Every field fix or recall for an emissions or driveability problem created more part numbers to keep track of. We are talking thousands of different PROMS. The General Motors PROM Identification manual that OTC used to provide with their Monitor scan tool and Pathfinder software contained more than 362 pages of GM PROM numbers![/align][align=center][/align][align=center]Enter the flash reprogrammable EEPROM (Electronically Erasable Program Read Only Memory) chip. PCMs built with EEPROM chips can be reprogrammed in a matter of minutes without having to remove the PCM or replace a single chip. It is all done digitally with the proper access codes and input data.[/align][align=center][/align][align=center][b]Following the Geo Storm, GM began phasing in PCMs with flash reprogrammable chips in a variety of cars and trucks. By 1995, most GM models had the flash reprogrammable PCMs. Ford and Chrysler were a

 

[align=center]Engine Management 101 - ECM [/align][align=center][/align][align=center]Click below link[/align][align=center][:-][/align][align=center][/align][align=center]https://montecarloforum.com/m_18213/tm.htm[/align][align=center][/align]

 

[align=center]Electronic Engine Management, Part 1
It's good to have an idea of how the engine management system works before you start modifying the engine!
By Julian Edgar

All engines require that the combustion air and fuel get mixed in the right proportions, and that each cylinder's spark plug is fired at the right time. Those are very important points to remember because it's easy to lose sight of these basics when making modifications or considering complex engine management systems.
Remember: it all comes back to:

[ul][*]how much fuel [/ul]

[ul][*]and when does the spark fire. [/ul]

Click below link for more[/align][align=center][:-][/align][align=center]https://montecarloforum.com/m_28954/tm.htm[/align]

 

 

untill i got moved to the cushy job, inspection used cars, i worked for the same companys gm service shop. looks like a pretty good description of how its done, but thought i'd add what i could

CDs went away a few years ago, everything is online now.

i never used a pass though cable, didnt have enough computers with TIS around the shop for everyone to be close enough, so we would just use the tech 2 to get the info we needed from the car, disconnect, hook up to a PC, download onto the tech2 then take it back to the car to program it.

noone in out shop would relearn the crank/cam unless they knew all of them recieving a particulat update would require it, or if the check engine light was on, it would set it right away. the relearn procedure is something that might be unsettling to some customers, and also why we dont do it to every vehicle. the relearn consists of selecting the relearn with the tech2 and then pinning the throttle to WOT w/the engine running! and then releasing the throttle as soon as the fuel cut off is reached. but then how else would you learn the full variance between the crank and cam positions?

 

 

well i havent reflashed my monte, but thats just because it already had the latest greatest when i got it. i belive there was either 3 or 4 programmings for it including the original programming. and then i'm sure there are abunch of VCI numbers GM has also. it would be nice if GM released a vci number to turn off the DRL's for everyone that doesnt like them, it'd be like free money for all the dealers that could charge an arm anda leg to anyone that wants it done. for what ever reason they make it vurtually impossible to get the vci to do it, i know our dealership did atleast 1 grand prix for the cop shop years ago. there were hrs spent on the phone, tech and service writter and service manager all complaining, and the whole proccess took a couple weeks as i recall.

 

[align=center]
How Car Computers Work [/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][align=center][/align][ul][*][align=center]The need for sophisticated engine controls to meet emissions and fuel-economy standards [/align][*][align=center]Advanced diagnostics [/align][*][align=center]Simplification of the manufacture and design of cars [/align][*][align=center]Reduction of the amount of wiring in cars [/align][*][align=center]New safety features [/align][*][align=center]New comfort and convenience features [/align][/ul][align=center][/align][align=center]http://auto.howstuffworks.com/car-computer.htm[/align][/align]