1227165 V8 ECM MemCal Resistor Network

resnet165.htm

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.

Useful links related to this project:

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 – FOR REFERENCE ONLY

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 Based: 1227165 ABYA Calibration (TPI)

All values in K Ohms

Raw measurements from chip (16-pin)

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

1

150

151

281

281

306.6

-

-

-

-

-

-

158.5

156.5

160

10

2

1.47

131

131

156.6

-

-

-

-

-

-

8.5

6.47

9.5

160

3

130

130

155.6

-

-

-

-

-

-

7.5

5

8

161

4

0

25.6

-

-

-

-

-

-

137.5

135

138.5

291

5

25.6

-

-

-

-

-

-

137.5

135

138.5

291

6

-

-

-

-

-

-

163.1

160.6

164

316.6

7

-

0

-

-

-

-

-

-

-

8

-

-

-

-

-

-

-

-

9

-

-

-

-

-

-

-

10

-

-

-

-

-

-

11

10

-

-

-

-

12

-

-

-

-

13

12.47

15.6

168.5

14

13.21

166.5

15

170

Raw measurements from experimental bread board using common resistors (16-pin)

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

1

150

151.5

281.5

281.5

307

-

-

-

-

-

-

158.3

156.5

160

10

2

1.5

131.5

131.5

157

-

-

-

-

-

-

8.3

6.5

10

160

3

130

130

155.6

-

-

-

-

-

-

6.8

5

9.3

161.5

4

0

25.5

-

-

-

-

-

-

136.8

135

138.5

291.5

5

25.5

-

-

-

-

-

-

136.8

135

138.5

291.5

6

-

-

-

-

-

-

162.3

160.5

165.2

317

7

-

0

-

-

-

-

-

-

-

8

-

-

-

-

-

-

-

-

9

-

-

-

-

-

-

-

10

-

-

-

-

-

-

11

10

-

-

-

-

12

-

-

-

-

13

11.8

15.8

167.8

14

13.26

166

15

170


The following chart is the raw measurements from the 14 pin chip and the chart is non-scalable.  I made the chart into an image due to the notes I made and figured that would be the easiest way to do it.  I didn’t resize it due to readability issues – anyway, it’s only a 16 color GIF which is only 12K in size so loading time shouldn’t be an issue.

(Click image for full size)

After looking at the chart, I started to notice some readings that were interesting. Not necessarily the values themselves, but the differences between the pins as noted above.  For example, looking at rows 1 and 2, from columns 10 to 14, I measured a narrow difference of 1.85K to 2.2K ohms.  Looking at rows 1 and 2 from columns 2 to 9 (before the red dividing line), I measured a difference of 2.2K ohms pretty solidly.  Almost to the point where you can say the difference in readings of pin 1 and 2 to all other pins is about 2.2K ohms. This may be a huge key in recreating the 14-pin chip resistor network (which is much harder than the 16-pin).


 

Here is a chart if the different year and Camaro models and their respective ECMs used:

Camaro/Berlinetta  
1992-90 6 3.1 Ltr. (189"-T) 1227730
1992-90 8 5.0 Ltr. (305"-F) 1227730
1992-90 8 5.7 Ltr. (350"-8) 1227730
1989-87 V6 2.8 Ltr. (173"-S) 1227302
1989-87 8 5.0 Ltr. (305"-F) 1227165
1989-87 8 5.7 Ltr. (350"-8) 1227165
1987 8 5.0 Ltr. (305"-H) 1228079
1986 4 2.5 Ltr. (151"-2) 1226864
1986 V6 2.8 Ltr. (173"-S) 1227302
1986 8 5.0 Ltr. (305"-F) 1227165
1986 8 5.0 Ltr. (305"-G, H) 1227169
1985 4 2.5 Ltr. (151"-2) 1226864
1985 V6 2.8 Ltr. (173"-S) 1226870
1985 8 5.0 Ltr. (305"-F) 1226870
1985 8 5.0 Ltr. (305"-G, H) 1226865
1984 4 2.5 Ltr. (151"-2) 1226156
1984 V6 2.8 Ltr. (173"-1) 1226455
1984 8 5.0 Ltr. (305"-G, H) 1226455
1983 4 2.5 Ltr. (151") 1226100
1983 V6 2.8 Ltr. (173") 1226025
1983 8 5.0 Ltr. (305") w/ Carb 1226025
1983 8 5.0 Ltr. (305") w/ TBI Fuel Injection 1226026
1982 4 2.5 Ltr. (151") 1st Design 1225570
1982 4 2.5 Ltr. (151") 2nd Design 1225610
1982 V6 2.8 Ltr. (173") 2nd Design 1225950
1982 V6 2.8 Ltr. (173") 1st Design 1225500
1982 8 5.0 Ltr. (305"-H) w/ 4Bbl. 1st Design 1225500
1982 8 5.0 Ltr. (305"-H) w/ 4Bbl. 2nd Design 1225950
1982 8 5.0 Ltr. (305"-7) 1225550
1981 V6 All 6 Cyl. 1224770
1981 8 4.9 Ltr. (301") 1224770
1981 8 4.4 Ltr. (267"), 5.0 Ltr (305"), 5.8 Ltr.(350") Exc. Air Cond. 1224810
1980 V6 3.8 Ltr. (231") 1224680
1980 8 5.0 Ltr. (305"-H) 1224670

 

 

 

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4 Responses to “1227165 V8 ECM MemCal Resistor Network”

  1. Cliff Harris says:

    The web site at
    http://www.iroczone.com/2009/10/1227165-v8-ecm-memcal-resistor-network/
    interested me so I did some analysis of my own.  I believe I have the correct version of both the 14 pin and 16 pin resistor networks.  I can send you a copy of the diagrams if you're interested.  Let me know.
     
    Regards,
     
    Cliff Harris

  2. freon says:

    Hi there,
    On the 14-pin package,Only CAL36, CAL38, CAL40, CAL42, CAL44 and CAL45 are directly measurable with an ohmmeter. The rest are intermingled with unrelated components and can possibly be found using lots of volt-drop comparisons. CAL55 and CAL57 appear to be the fuel pressure/volt compensation string, CAL56 is injector/ref ratio for choosing cylinder number vs number of injectors. The architectiure is mostly indentical across several 16094995 – 16034984 chipset equipped ECMs. I'm working on an L26 project car and even though the 16-pin layout might not match perfectly I thought I'd share

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