Update 01/19/2005 - I have kind of given up on trying to "reverse engineer" the 14-pin resistor pack on the 165 V8 MemCal, at least for the time being. After I finished the 16-pin, I was all excited about decoding the 14-pin, but ... the headaches ... The following documentation is left here as reference as it still may provide some other useful information and maybe someone will take this over. The problem with this type of hacking, is that there are many different variants of the resistor pack and even if we were to decode this one, there are others to consider to make this worth while. On the same token, from what it seems, it wouldn't be feasible to create a home-made resistor circuit to replace the chips as it would take up a lot of room. Perhaps, one day, GM will stop carrying replacement MemCals and from there, we would probably need to think of something. But until then, most MemCals can be obtained for less than $50 from your local GM dealer or GM Parts website online. The new article will have part number references from various sources to help along.
But here are a couple of questions for folks that are reading this. First, how can you just get the resistor packs? How does Hypertech do it? Do they get OEM MemCals and replace the chip (I tried that, it's not an easy task), or have they found a way to reproduce the resistor packs? Hmmm ... something to think about. Anyway, thanks for everyone's help. I will be creating more of an organized article in conjunction with the EPROM programming article. Reference numbers, part numbers, etc. UPDATE: It's available here.
- ECM File Repository (BINs, ECUs, Schematics, etc.) - NOTE! Use at your own risk! IROCZONE.com or any of it's affiliates are not responsible for the use or misuse of bins and/or information located in this link.
Useful links related to this project:
- GM_ECM (http://www.diy-efi.org/gmecm)
- Ludis's Home Page - Excellent source for cross referencing resistor packs with model, year and ECMs used. (http://www.cruzers.com/~ludis)
There, we're doing it, now! Along with some help from Craig Moates, we're going to throw everything we have on the plate here in hopes that we can gain help on figuring out what those resistor network chips consist of and how to duplicate them. At the very least, determine a way to get spares for our ECM "hacking."
The following information is based on resistor chips from the 1227165 ECM, part numbers 16055375 for the 14 pin chip and 16055376 for the 16 pin chip. I believe these chips are used on all IROC-Zs in 1987 and 1988, but I'll have to double check and make sure so don't quote me on that!
|
DO NOT USE - Here is a VERY rough draft of my initial research in determining what the 16-pin chip consists of on the 1227165 ECM MemCal from a 1988 IROC-Z, 5.7L Automatic car. It has since changed and I also have attempted to mimic the resistor network on a bread board with nice results. Most connections are right on and a few are slightly off from initial measurements. I'll try to get the newest draft up here soon. The 14 pin is under work and received work from Craig Moates as well as taking my own measurements from my MemCal to determine if it's possible to "rebuild" that chip as well.
Here is the latest draft. This was made from the original draft, after using the bread board with commonly obtainable resistors from Radio Shack. The figures between the pins are as set up as raw measurements from the chip, then the raw measurements from the bread board. As you can see, most are extremely close, however, there is one that is a bit too far off for my taste. For example, the measurement between outputs 57 and 59 were measured at 25.6K, but using two common 51K resistors in parallel, I was able to get 25.5K ohms. Very close. But, the pins between NC and the 56 (No Connection) were measured at 12.47K on the chip, but managed to get 11.8K from the bread board. This was done to solely concentrate on the other values from "used" outputs to be as close as possible and for overall simplicity and reproduction from commonly obtainable resistors. We "could" use higher resistance (somehow getting to 7.4K or 7.5K ohms) on pin 13. The charts below should demonstrate how close the "used" ports are to the raw measurements from the chip versus the bread board. Check outputs such as 56 to 55 or 57; or outputs 56 to 59; or outputs 50 to 57, etc. GM Resistor Network
Resistance Tables All values in K Ohms Raw measurements from
chip (16-pin)
|
