in winaldl i think it is called a flag or error. i see the box checked for eprom error. never noticed that till a week ago. could that be from a prior screw up and the ecu holds onto it forever. disconnect battery cable to clear it? or is it due to fact my 7747 has wrong memcal(limp) or whatever it is called in a 7747. i think original (7747)came out of V6. do i go to junk yard to get one from v8 or is a burn possible? what year van/thuck had 7747 V8? my eprom(s) works fine by the way so that is not it.

 

IIRC, it takes 50 clean starts for a code to be cleared.

 

when i loaded a blank eprom into zif socket i think it went to memcal in limp. car would barely run. can i burn one or go to junkyard? see my post.

 

Get one from a V8 truck thats close to your present setup and use that bin as a base. You probably can also jsut download a binary image and burn that if you have some 2732 chips handy. Dont know which one youd want, though.

 

so the memcal uses a 2732? i was not aware of that. so i just burn another and swap it out of carrier. is 7747 a special carrier for memcal? i believe the 2732 is a 24 pin devise?

 

the 747' and 746 don't use a memcal. Thats TPI stuff. You just got your chips in funny and tripped the prom code. I've been running it for a while and haven't had any problems....We'll i'm having problems but I don't think their related. For some reason I can't get my open loop idle, highway mode, and TCC control to work. Any one know what qualifier is needed for all 3?

 

7747 has no provision for "limp mode" ? did i misunderstand. actually i did not see a second chip come to think of it.

 

To my understanding all C3 ecms have limp home mode where it just runs off of the hardware in the event of a prom or other failure.

 

hmmmm. mine would not idle and died. but b4 i let it die i revved it and extricated car from bank auto teller. lucky me no traffic near bank.

 

Check out the MEMCAL, PROM, . . . sticky on the DFI & ECM board. There are pics and a brief description of the various parts.

One reason a modified setup can die while in limp mode is that the CALPAK is no longer properly calibrated. With the smaller PW's at low speeds a stock limp mode CALPAK will drown the engine with fuel.

The '747/'8746 limp mode resistors have been hac'd. There is a write up floating around someplace. I may be able to find it.

As for erasing EPROMS with sun light, yep, will do it. The heat doesn't help either. I use and recommend a small piece of electrical tape over the window. Upon removal for erasing if it leaves residual can clean it with BrakeKllen, Goof-off, or some other such solvent.

RBob.

P.S. way back while hac'ing Atari's and such we would place the EPROM's out in the open sun for a week or so, couldn't afford a real eraser. . .

 

RRob: it appears i have a prom with calpack(7747). obviously not a memcal. I visited that topic DFI/ECM but did not search. calpack has been hacked? is the calpack a pin devise that i can program with my pp2? is it soldered in place? i think a while back i was advised to swap out the calpack for a v8 model as i currently have a v6calpack in my 7747. never needed it till now. regardless even a v8 most likely wont run well should i need it again. is this big dea?. i was thinking of carrying a back up(duplicate) chip as a spare. this is the first time it has happened to me and i think it is a direct result of swapping in a ZIF as it happened 2 days later. car runs fine but have not run it for a week as monsoon season.

 

The CALPAK is a network of resistors. It is re-programmed by adding resistors to it. Or creating another network.

The '8746's are soldered in (only used on V8's), the '7747's are socketed as there are two different ones: V6 & V8. The BBC & SBC V8's both used the same CALPAK. There is an I4 one around from another ECM that can also be used.

Need a scope to change them as when in limp mode no ALDL is available for PW. So, read the PW's with a live PROM in place and duplicate them with the CALPAK (using a scope to read the PW). An ECM bench helps out.

RBob.

 

RRob: one more please. would it not be easier to just carry a backup eprom chip in glovebox if eprom fails ? i understand car might be safety compromised if it dies in traffic but it did run so/so (filthy rich) in limp. if i swap in a V8 calpack (socketed?) is it an easy push fit?.

 

All depends upon how long it'll run until plugs foul. A V8 CALPAK will produce shorter PW then the V6 version.

I only added three resistors to get it decent in limp mode.

RBob.