When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Memcal in the ECM control unit
I speak german and no english i have translated with google
I would like to secure for the future something and lay down difficult parts for me.
I bought an ECM ECU from a scrap dealer in the USA.
88 89 90 91 92 93 CUTLASS SUPREME ENGINE ECM ELECTRONIC CONTROL MODULE OEM
The ECM I cleaned and removed from my ECM the memcal AXCN and inserted into and into the cutlass supereme ECM.
Yesterday I destroyed some gasoline.
My vette ran as usual.
In the cutlass superme ECM a memcal AXKK was installed.
My question one can the AXKK somehow convert it as AXCN runs.
The eprom must be rewritten to me is already clear to me is the knock sensor board and the two ic which are designed for the emergency run.
The knock sensor board and the two ic are only tied to the one vehicle or can be because of what is fashionable.
On a reply I would ferret.
kleiner53
I believe I understand the OP's question. He's likely got a '90 or '91 L98 and the 1227727 that he's bought is correct for the car. He's curious as to whether the V6 PROM can be rewritten to be used in the V8 application.
I don't know the answer but maybe it's more easily understood.
If you had a UV eraser and a PROM burner you could do what you want, but the cost would be pretty high for a one time project. Sometimes the old PROMs will not erase properly and then you can't burn it. The other problem is that you can't but these old PROMs as new. You could buy some old ones.
If you had a UV eraser and a PROM burner you could do what you want, but the cost would be pretty high for a one time project. Sometimes the old PROMs will not erase properly and then you can't burn it. The other problem is that you can't but these old PROMs as new. You could buy some old ones.
I'm inclined to think it's NOT that simple. I believe that the PROM is actually different and there are likely known issues. I believe it can be done but it's likely not very desirable, I believe that if a V6 PROM is rewritten to a V8 file maybe the "limp home" is defeated. I don't tune or know for fact but it seems that I've read that in the past.
Someone will stop by today I'd think with a definitive answer.
I'm inclined to think it's NOT that simple. I believe that the PROM is actually different and there are likely known issues. I believe it can be done but it's likely not very desirable, I believe that if a V6 PROM is rewritten to a V8 file maybe the "limp home" is defeated. I don't tune or know for fact but it seems that I've read that in the past.
Someone will stop by today I'd think with a definitive answer.
I took a closer look at the PROM used in the picture, a 27C256, which checking the datasheets is a one time programmable PROM. That means you are correct you cannot reprogram an old one. However if you can find a 27256 (without the C in the part number) it is a UV erasable PROM with the same pinout as the 27C256. You could then copy the programming from the PROM to the 27256 and have a copy of your MEMCAL.
I took a closer look at the PROM used in the picture, a 27C256, which checking the datasheets is a one time programmable PROM. That means you are correct you cannot reprogram an old one. However if you can find a 27256 (without the C in the part number) it is a UV erasable PROM with the same pinout as the 27C256. You could then copy the programming from the PROM to the 27256 and have a copy of your MEMCAL.
The prom is UV erasable and can be erased with a UV light and reprogrammed, but it is a pain because it takes some time and it does not always work the first time. If you buy a 27SF512 chip and a G1 adapter from Moates you can use the original memcal and mount the new chip in the adapter and program the new chip to do what you need.
If you are handy and patient you can desolder the old chip from the memcal and put the new 27SF512 in its place and then you do not need the adapter.
As far as the memcal is concerned the V6 memcal will not have the correct limp home functions in it so I do not believe it will work in the place of the V8 memcal, but i have never tried that so maybe someone else can chime in.
Last edited by bjankuski; Oct 19, 2016 at 12:55 PM.
In my opinion it's virtually impossible to get into limp mode. It requires the microcontroller to stop executing instructions and stop resetting the watchdog timer. When the watchdog times out it resets the microcontroller and the program starts over as if the ignition was just turned on for the first time.
Limp mode only happens when the microcontroller is completely dead. The FMD (Fuel Modeling Device) takes over and uses the resistors in the MEMCAL to adjust the fueling and timing.
There are some jumpers inside the MEMCAL that determine if it is programmed for a 4, 6 or 8 cylinder engine. I have seen instructions for changing the jumpers to make a 6 cylinder EPROM work in an 8 cylinder engine.
The prom is UV erasable and can be erased with a UV light and reprogrammed, but it is a pain because it takes some time and it does not always work the first time. If you buy a 27SF512 chip and a G1 adapter from Moates you can use the original memcal and mount the new chip in the adapter and program the new chip to do what you need.
If you are handy and patient you can desolder the old chip from the memcal and put the new 27SF512 in its place and then you do not need the adapter.
As far as the memcal is concerned the V6 memcal will not have the correct limp home functions in it so I do not believe it will work in the place of the V8 memcal, but i have never tried that so maybe someone else can chime in.
Looks like his MEMCALs have sockets for the PROM. I am not sure if the MEMCAL for my '92 is the same way, but will check.
I have not tried this, but can't see why you couldn't load 2 PROMs/tunes worth on the 27S512 and setup a dip switch so that you could easily change from one tune to another. It has twice the storage of the factory PROM.
Looks like his MEMCALs have sockets for the PROM. I am not sure if the MEMCAL for my '92 is the same way, but will check.
I have not tried this, but can't see why you couldn't load 2 PROMs/tunes worth on the 27S512 and setup a dip switch so that you could easily change from one tune to another. It has twice the storage of the factory PROM.
You can put two tunes on the chip and use switch to change between them.
the 92 is the same as his chip, with some patients you can remove the original chip and solder in a new chip.
Memcal in the ECM control unit
