ECU's

I am very confused with ECU's and everthing I read about them makes me a little more confused. DSM link requires an EPROM ecu correct? What is the non EPROM ECU called? When and on what models were the EPROM ECU's put on? What is up with OBD and OBDII? What do they mean? People in the Cavalier forums talk about them all the time and I got really confused when people here started on them. Any clarification would be greatly appreciated. Thanks guys.

I am very confused with ECU's and everthing I read about them makes me a little more confused. DSM link requires an EPROM ecu correct? What is the non EPROM ECU called? When and on what models were the EPROM ECU's put on? What is up with OBD and OBDII? What do they mean? People in the Cavalier forums talk about them all the time and I got really confused when people here started on them. Any clarification would be greatly appreciated. Thanks guys.


On Board Diagnostics 1 and 2.

OBD2 didn't start until mid 95 model year and the beginning of 96.

Different ECU's can be reprogrammed and/or flashed, and can be chipped. Others can't.

the eprom cam on the 95 turbo mobles. obd and obd2 is on board diagnostics and on board diagnostics generation2. basically obd2 is standard on all 96 and newer vehicles and requires them to have a data port under the dash on the drivers side and when you have a dtc you can pull the code from that port and its generic so anyone with a scan tool can read it obd1 is different, i cant remember exactly what it made manditory but it has alot to do with emmisions

the eprom cam on the 95 turbo mobles. obd and obd2 is on board diagnostics and on board diagnostics generation2. basically obd2 is standard on all 96 and newer vehicles and requires them to have a data port under the dash on the drivers side and when you have a dtc you can pull the code from that port and its generic so anyone with a scan tool can read it obd1 is different, i cant remember exactly what it made manditory but it has alot to do with emmisions



Car company's wanted a universal diagnostics system to pull codes. That port isn't required on vehicles though, take hondas for example, it takes a special plug in to read codes on the right side of the dash, at the ECU, not the usual 16 pin connector like most cars have.

A vehicle can't claim to be ODB2 compliant but not use the standard OBD2 connector. Are you thinking of older honduhs? There are 3 versions of OBD2, so its still not quite standardized. IIRC chey and ford each have their own, and chrylser and imports fall under the ISO version. I know there are 3 types, I may have the breakdown wrong though.

All 95 and up DSMs were OBD2 even though it wasnt officially required by law until the 96 model year. And it was the US government that pushed for on board diagnostics for emissions reasons, nothing to do with making it easier to pull the DTCs.

The only 2g DSMs to come with EPROM ECUs (Electronically Erasable Programmable Read Only Memory) were the 95s and not all 95s had one (like mine, wtf... June 95 build date :) ). The EPROM is reprogrammable which allows us to change the instructions with a chip or DSMlink. The non-eprom ECUs are called just that. ;)

ODB1 was the first attempt at this, but it was not standardized well at all, but did serve the purpose of being able to do self diagnostics on the emissions system components. ODB2 was standardized better and monitors more things, like cat efficiency and misfire detection (thats why all 2gs have the rear o2 sensor and seperate cam and crank angle sensors), and other things. 1Gs had a form of OBD1, but it is specific to the 1g DSMs. A 2g logger will work on dozens of different cars, while a 1g logger works only on 1G DSMs.

1Gs had a form of OBD1, but it is specific to the 1g DSMs. A 2g logger will work on dozens of different cars, while a 1g logger works only on 1G DSMs.

Just outta curiosity, can a 1g ecu be flashed and/or re-programmed? And if it can, what reasons would someone have to perform such a task if our ECU's are self learning and pretty much any variable has a sensor?

What about the 1g's? Did any of them have eprom's or was it just those few in 95?

All years of 1Gs had some percentage of EPROM ECUs as far as I know. The original upgrade was a TMO chip (www.TMO.com, even though they fell off the face of the earth), which offered such things as removed fuel cut, octane reset on restart, kills the AC compressor over 5k rpm (2g does this stock), stutter box launch, stutter shift, 1Gs got a cool security feature, useles stock boost guage became 5 selectable guages, like knock/timing/etc, modified rev limit, the list goes on.

The current source for chips for DSMs is Key Diver, www.dsmchips.com. Pretty much the same selection of mods as far as I know. They do offer injector compensation though, which is like adjusting the global value in DSMlink. THe advantage to this is that you can run large injectors, and still leave your AFC at zero to start, so you still get the full +- 50% range of the AFC, and timing isnt completely shot to shit from a large airflow signal change. I highly recomend poeple take advantage of this if you are not running DSMlink.

The next option is obviously DSMlink, and that is obviously my favorite. The Keydiver chips are much cheaper than the TMOs were, but add up the cost of the chip, the AFC, and the logger, and it can make DSMlink seems a little less expensive.

All of these options will require a socketed ECU. The stock chip is removed, and a socket is soldered in it's place, making it easy to swap between chips. The place selling the upgrade should be able to do this service for you for about 30 bucks (exept TMO of course).

THe TMO website has good instructions and pics for checking your ECU for an EPROM.

Mine has EPROM :grinyes: I checked. My car build date is november 94. Over the winter i am getting DSMLINK put in mine.