I'm kind of lost a little bit on MemCals. I believe I have a APYP for my 88 IROC 350 TPI. What is that exactly? Is it just the programming on the chip?

Reason why I ask is I plan on getting a handful of MemCals to play around with so I don't mess up my original. What MemCals can I use with the 165 ECM? Are the "resistor packs" or whatever they are, next to the chip, the same? If a MemCal from a 165, no matter what year, engine, will work with my 165 as long as the chip is programmed correctly?

MemCals from other ECMs, look the same, replace the chip, what happens?

Thanks for the help.

 

If you reprogram the EPROM on the MemCal (the bigger 28 pin chip under the blue cover), you can use any 165 MemCal...But the Limp-Home mode chip (the little one next to the big one) won't work right *unless* it's from a V-8...

You are correct, APYP is the binary code on the chip.

Trying a chip from a car other than your own could be diastrous...GM doesn't put the code in the same place on the chip from car-to-car, or even from year-to-year...

Your 165 has a 128k EPROM. The later model years 730 have a 256k EPROM. They look alike, but I don't believe they will interchange.

Good place to find out what EPROM you have is at -

http://holman.cs.uml.edu/~sdurphey/bccfind/

 

Right. My main concern was the brown piece the chip plugs into. Let's pull the chip out of mine and stick it in another MemCal, then plug the memcal into my car. Same chip, different "limp chips" I guess you could say. As long as it's a V8 memcal ... .should it also be from TPI? or does it just have to be a V8 ...

 

My experience with memcals has been to run the closest application you can to the stock one. The closest MEMCAL got me to and from my finals when I ended up having a broken pin after I inserted the EPROM into the socket. My worst experience has been 2 miles away from home with a V-6 memcal and an 8 cyl. engine. Needless to say, I will NEVER do that again.

Learn from my mistakes! After the 2 mile walk, I let the car sit in the drive for a week before I got a correct MEMCAL, but I would still wait another week if something happened to my current one. -Matt-

 

You sound as if you want to pull the EPROM out and stick another one in...It's not quite that easy...That's a soldered-in EPROM...Even if you can pry it out without ruining the pins or the socket, you may not get a good connection trying to push the next one in...And the EPROM you pull out may no longer make contact with the next socket...

Desoldering is the accepted way to do it; soldering in a ZIF socket gives you a good contact socket; and you may as well toss that pulled-out EPROM...(after downloading the BIN!)...Because it's not worth the risk of having a bad contact in the middle of rush hour traffic in an insane city...(EPROMs are only like ~$5.00)...Plus you can use the 29C256 EPROM instead of the GM 27128...

 

Okay. I understand the issue with desoldering the EPROM out and everything. I'm trying to make this so I can understand this. I'm not sure If I'm making myself clear or my posts aren't being read thouroughly.

HighHopes85 has come the closest in answering my question.

Let's say I have 3 EPROMs, exactly the same, programmed with my original BIN. I take my ORIGINAL MEMCAL ASSEMBLY (including the EPROM) out of the ECM. Put it aside. Leave it alone. All together, blue cap and all.

I have 3 of those little brown memcal things with EPROMs taken out. ZIF or regular sockets put in in place of the EPROMs. I have no idea where these brown "memcals" came from. They all have a small circuit or a couple of chips on them next to where the EPROM goes in.

I put my 3 EPROMs in the 3 brown MemCal "shells" Remember, they all have the same original programming on them.

What will this do?! So far I understand that they have to be from a V8. Does it matter if it's from an 89 Chevy Truck w/ 305 TBI? 87 Camaro 305 TBI?, hell a 92 Chevy Truck w/ 454 TBI? What "brown parts" (memcals w/o EPROM) can I use in my 88 IROC TPI 350, granted I have the SAME EPROM chip (chip I mean JUST THE CHIP, not the entire MemCal assembly).

Whew ... hope that was clear.

 

If you have your heart set on doing that, the only advice I can give you is to not desolder your good, known stock one. It sounds like you have the original one that came in the car. Keep that one in your glove box. THEN, if you feel inclined to make the other 2 with ZIF sockets, that could work out for you.

Someone might chime in and let you know if cylinder select is on the NETRES or on the EProm. I believe it is on the MEMCAL for the speed density proms. If it is on the NETRES however for your calibration, then you will be up the creek.

I don't know enough to answer your current question, which is "How much does the NETRES information for fuel and spark change from a 305 and a 350 and also, how much is it changed based on an automatic or manual tranny".

But I will tell you something from experience. I ordered a handful of pulls (aka used chips) when I was working on my MAF setup. I was originally going to program 4 chips at a time and drive around to see which one worked best. After day one, I realized if I wanted to do things correctly, I was wasting my time if I took more than one good known backup and one updated calibration with me. I was trying to kill 4 birds with one stone and in the process, was not learning enough about changing things correctly.

From what I've learned, I can't guess when the computer is going to go into limp home mode. Sometimes a chip will erase and burn great at a certain erase time, but will set a code about 5 minutes into your driving. If you don't keep that stock MEMCAL in your glovebox, you might be walking too

-Matt-

 

Yes, Matt, thanks! That is the whole idea of picking up a handful of spare MemCals so I can pull my original one out and put it aside. That way I can play with the spares I have. Problem is, I don't exactly know if these other ones will work. Obviously, I'm not going to use the EPROM code that's on them, My main concern is the, I guess "NETRES" on the other ones be compatible with my setup, then program another EPROM chip plop it on one of these other Memcals and go!

 

The memcal contains the following:

cylinder select
limp home fueling calibration.
ESC filtering (ESC= Knock sensor)

If you like rolling dice you can play around, er, make that if you don't mind walking home, and shortened engine like.