I was having a conversation with a friend the other day, and the question came up of if we could take any prom from a Speed density ecm (other than a 730) and use that chip to burn with if the files were loaded onto it. Is it possible?

 

I'm assuming you're using the word PROM to mean the actual chip, and not the entire MEMCAL. In other words, you're asking if you could recycle EPROMs from other GM applications?

Answer: Sometimes.

Some P4 MEMCALs had to have a 256K chip, some only had a 128K chip. And sometimes GM used 256K chips where only a 128K was needed. So, if you have a '730 and want to run $8D, your donor MEMCAL would need to have a 256K chip.

In reality, I doubt there's much recycling of old GM 27128 or 27256 EPROMs going on, since new ones only cost a few bucks, and compatible flash chips are available that are much more convenient to work with.

I hope that answers your question.

 

For the most part, yes. We have some spare proms laying around. Maybe we should try it.

 

And AT29C256 EEPROMs are only a few bucks

 

Well, will the memcal from another ecm work? I have those laying around also. (spares?)

 

It depends. At a minimum, the cylinder select, and ESC stuff has to match up. So, you'd be asking for trouble if trying to use a V6 MEMCAL on a V8, or trying to use a '165 MEMCAL in a '730 or '749, for example.

If you're like me, most of the extra MEMCALs you have lying around came from 4- or 6-cyl apps, which makes them basically useless, if you're intersted in V8 applications.

 

I was under the imporession that it was ok to use a memcal from a 6 cyl application, as long as the prom had a 8 cyl .bin written to it. Is this incorrect?

 

I've tried that a couple of times on the ECM bench, and it's never failed to produce really wierd results. Also have heard of quite a few tuning headaches over the last few years, caused by people trying to do the same on real world apps. There may be some exceptions where it works, but I don't recall ever hearing of any.

Dunno if anyone's developed a workaround -- for the price of a V8 MEMCAL I don't see it being worth the effort.

 

bummer :-(

 

Yup, I have quite a few from 4 cyl. and v6's. It was worth asking at least. Maybe I could give them away as door prizes or something.