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CeC technical information? |
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MIPS
AMC Nut Joined: Mar/11/2019 Location: Kamloops, BC Status: Offline Points: 346 |
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You are not wrong there. From the mechanics manual alone there's indication of at least four revisions of the CeC before the Eagle went to TBI and a completely different arrangement.
First revision CeC (with DTC and CHECK ENGINE circuit) Second Revision CeC (without DTC and CHECK ENGINE circuit, due to CPU constraints) Third revision CeC (the "C4" system) Fouth Revision CeC (Ford ECU?) The ultimate goal is a drop-in replacement to the CeC that keeps the car compliant with regional emissions testing and otherwise identical performance while being made of modern components, however the added bias control of the fuel mix and ignition advance to work around the major shortfalls to the original CeC's locked-in emissions limitations. No fancy displays, no new wiring, no complicated instructions. Just plug it in, tweak a knob or two while tuning to your desired spec and you're set. System diagnostics otherwise remains the same. |
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tomj
AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7522 |
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OH. i musta missed that. in that case, since you have a good one now, don't take it apart! use it as the standard and measure what it *does*. watch, in real time, what a critical output does in response to an input. THAT is what is important. characterization. my guess is, it will be hard to get started, to figure out how to look at. off the top of my head, with an oscilloscope figure out what the inputs and outputs look like, electrically -- 12V PWM stepper? analog input? pulses? voltage levels and speeds and pulse widths, not meaning or intent. chances are this stuff will be relatively easy. install a good wideband O2 sensor, kludge up an Arduino or two to sense (A to D, or code to parse PWM on time (you could probably do 1% by taking a 12V stepper output, passing it through an R C low pass network (integrator) then reading the resulting voltage via Arduino analog in. the delta will be important, not so much precision. *when* does it enrich the carb? also you probably "know" spark control will be a simple 2D map; load (vacuum) and rpm. no real need to worry about the electronics there, just work out what the map is. that's easy! pull the vacuum hose (or fool CeC with a MightyVac), measure spark advance wiht a timing light at 500, 1000, 1500, ... 4000 rpm with no vacuum (that's "mechanical" advance) then at say 500 rpm, use the mightyvac to vary "load" and measure advance at 100, 90, 80, .... 0 KPa. then simply extrapolate in a spreadsheet. that's how i first populated my Megajolt box the first time, reading distributor with hose off etc. carb will be slighly harder, but once you get into it probably doable. get one od Afafruit's boards with built-in SDcard, and write a datalogger that outputs "columns" in CSV format. that's what my datalogger does and it's easy to do a rough job for your debugging. document CeC's *functions*, it's guts are uninteresting. |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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amcfool1
AMC Addicted Joined: Jun/18/2011 Location: roanoke va Status: Offline Points: 1071 |
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hi, if you need one to take apart, I have an old 82 that's all there, though the aluminum case is corroded some. Don't know if it still "works", though it should, as it hasn't been in use for the whole time I had the car (82 Eagle), since I did the MC2150/HEI thing. It just sat there for over 20 years. Yours free if you want, just give me a couple bucks for shipping, (from 24017). thanks, gz
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george z
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MIPS
AMC Nut Joined: Mar/11/2019 Location: Kamloops, BC Status: Offline Points: 346 |
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It's so simple. AMC in the process of making it cheap to impliment made all of the sensors extremely easy to monitor and troubleshoot. With the exception of the O2 sensor which operates within an analog 0v-1v range the entire system is 12v digital and every sensor is either on at 12v or "off" and tied to ground. No pulses, no protocols and no weird switching states. AMC's own documentation is quite comprehensive in how each of the different open loop system states are created before the engine finally qualifies for closed-loop. The stepper motor is a simple two-phase circuit. On top of the original tool that OTC sold for diagnosing the electronic feedback system I've been developing my own unit that allows for more status information to be displayed at once than the official tool allows. This is basically what I am using to verify AMC's own documentation and hardware before committing further.
That's fine. I'll send you a PM. Ultimately depotting can start either by milling off the aluminum frame to release the epoxy block or skip that step entirely and boil the epoxy until it softens. (see https://www.youtube.com/watch?v=OiPe6f4Oh8E ) Ultimately if that fails then it goes under the CNC machine and the resin is milled off layer by layer until it's thin enough that the rigid epoxy can be again boiled and pried off. Part of the goal if AMC/GM handled the CeC's ROM correctly is that if it (the ROM) can be extracted from the CeC, dumped and then the original timings and fuel tables extracted from the disassembled code they would not have to be redeveloped from scratch which is where my shortcomings in software development show but up to that point, hardware development is my specialty. ;) Edited by MIPS - May/05/2019 at 12:01am |
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Greyhounds_AMX
AMC Addicted Joined: Nov/14/2009 Location: Kansas City Status: Offline Points: 1268 |
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How about replacing it with a Speeduino? That would give alot of flexibility. Not sure about running the stepper though.
I suppose with Speeduino it would be easier to switch to TBI.
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1968 AMX 390 w/T5
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tomj
AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7522 |
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WOW! haha yeah that's a lot of good information. good old TSMs! realistically you should assume that there are variations from the TSM, i mean what electronic product doesn't require tweaking in production etc? but its probably a good start. you could code from what you;ve got there. what exactly is the point of depotting? i seriously doubt you'll get very much insight into how it works. nice test box! yeah, you gotta make something that lasts to persist at it. nice job. O2 sensors are tricky sensors they're anything but linear. the so-called wideband sensors are a lot more proportional and can be made linear with processing. lambda sensors have a super-sharp slope around stoich and so most systems have an abstraction that essentally calculates the ratio of "too lean" to "too rich" time, with L/R flipping back and forth rapidly (GM TBI does this) then using that ratio as "A/F ratio". it's not really possible to control mixture so that the sensor outputs 0.45V. nothing in engine operation is that time-stable (Variable speed, variable load, etc). that prose description and the pinouts/signals is great information! |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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MIPS
AMC Nut Joined: Mar/11/2019 Location: Kamloops, BC Status: Offline Points: 346 |
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I did look it as a potential replacement initially but the problem I found was that it's really reliant on several additional sensors an Eagle traditionally does not have and I wasn't interested in a replacement that also required multiple existing sensors be replaced or upgraded. It's also way more powerful than what an Eagle needs with a stock system. Remember that the more complicated the replacement is to install, the less people are interested in committing rather than just doing a full bypass. Building a replacement does involve starting from scratch but the digital input and output nature of the CeC coupled with relatively low sample rates makes it WAY easier to duplicate compared to even first generation TBI computers.
Depotting helps identify the microprocessor used, the location of the calibration ROM (which may prove helpful for when creating the same calibration data on the Arduino so you are not making wild guesses) and identify the location of any components that are known to fail with age (lytic can capacitors for ripple smoothing or AC decoupling) or input and output buffers that may be easily or accidentally blown. Computer replacements are costly if your region mandates it be working. If it's built from relatively common parts and we can map out the location of the various circuits then repairs may be as easy as someone ball milling out a chip and soldering in a replacement. Think like how some guilty folks in the 80's and 90's piggybacked new EPROMs into their VideoCipher satellite descramblers. It also verifies that there is no other "secret" connections going on. Note on the diagram above the CeC connector has four unmarked pins. What do they do? Where do they go? O2 sensors for the 82 year Eagle are compatible with the NTK 23552. It's one of the few parts in the CeC that MUST be replaced as per its recommend 30000 to 50000 miles, otherwise the computer enters closed loop and cannot accurately regulate the mixture. This is also your only time in which you can justify having the emissions maintenance timer installed. Really I'm just bored right now. I need something to keep my mind busy and this could keep me going for the rest of the year. Edited by MIPS - May/07/2019 at 8:55pm |
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MIPS
AMC Nut Joined: Mar/11/2019 Location: Kamloops, BC Status: Offline Points: 346 |
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Well this is a pleasant surprise.
So the silica-mixed resin used to pot the CeC turns into a sticky wet sand when boiled, however makes removing it a billion times easier. Beneath it all has so far uncovered an Intel 8049 8-bit Microcontroller which was introduced in 1976 and discontinued in the early 2000's The datasheet for this microcontroller can be found here - https://www.ceibo.com/eng/datasheets/Intel-8048-8049-8050-plcc-dip.pdf The 8049 specifically is the same microcontroller as the 8048, however with 2kb of onboard ROM and more ram, so the precious calibration data is hidden in the chip, but because many hundreds of thousands of products used the microcontroller well into the 21st century the procedure to dump it is well known. I'll keep working away at the resin and see if I can free the board from the body. Edited: Pretty much done. Even simpler than I expected. Microcontroller, what looks to be two drivers, a regulator and some other IC I've not really investigated yet. No drivers and no buffers, just a lot of diodes and resistors. I'm going to bed. Edited by MIPS - May/26/2019 at 1:48am |
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tomj
AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7522 |
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nice work! lol. i still sort-of remember the 8051 instruction set from ye olden dayes. ugh! lol. but that's good depotting! of course the code is key to the realm... |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4741 |
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Really awesome to see this.
I wonder what the 1984 and up ECU looks like inside and what processor it uses. MY father built Apple IIE computers in the 1980's when he lived in the San Francisco bay area and still has his PROM burner, so I figure he could help me out if my ECU ever takes a dump. 1984 and up ECU is definitely made by Ford, though as I understand it, no vehicles other than AMC ever used it. I suspect the folks over at the Eagle's Den forum know more about this than most folks here. Eagle people are like their own community within the AMC community. It makes sense too, since Eagles are their own unique realm of AMC. They're just different enough from all other AMC cars to make them their own thing. |
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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