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I would start with routine servicing: plugs, wires, valve clearances... A problem in the Good Olde Days was people trying to tune their carburetors with old plugs and loose valves, which is basically impossible. Same thing now: do the maintenance items before starting the complicated debugging.
 
Discussion starter · #23 ·
Harder. It was getting pretty mindless and I was thinking of all the other things I wanted to do (the ones I need to do lock themselves out of my mind automagically) so I called another member on the phone and chatted while I did the rest... so they are DONE!

Now to test them. Murphy and I are good friends so I can't wait to find what mistakes he has laid for me.

You can see where I changed techniques.
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Discussion starter · #25 ·
powered through it tho, looks nice too.
Not any more:
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I need to lengthen four or five wires and add about 25 to get 100% connector coverage. This will then let me examine every signal in the MCM and ECM. Considering creating a markdown file for each ECU describing each signal with sognal screenshots from the logic analyzer/oscilloscope but given how long it took to get this far, I am concerned... Maybe I can fill it out as needed.
 
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Discussion starter · #27 · (Edited)
hmm.. do you have sacrificial test modules? how many different ones are there?
There are almost as many (or more) BCM, MCM, and ECM versions than model years of G1 Insights. But I got my printed circuit board connector from a 1998 Civic ECM. However, you can purchase some of these ECU connectors and extra pins from Mouser and Digikey (TE Connectivity AMP .040 and .070 Multilock series.)
 
for the logging part of this, are you just using your scope?.. just curious if you have intentions to input the data into separate logs and keep it all organized... im familiar with software where you can compare excell charts to frequency graphs like audacity and individual parameter values on a sidebar all at the same time once you have all of the inputs identified and scaled properly.. i have 100's of logs where i added notes and file through to compare mods and tunes 'cause and effect tuning on the road',, how are you going to organize the data? if you don't mind me asking
i know people that do these sorts of reverse engineering have used TunerPro free software.. i know you are technically minded, i just find all of it very fascinating from a distance. not trying to annoy and more trying to better understand, also sorry if you coded it into your previous posts and i didn't catch it
 
Discussion starter · #29 ·
I will start with a Saleae Logic Pro 16 which has sixteen channels of logic or oscilloscope functionality (thank you Saleae for the maker's discount!) The oscilloscope is limited to +/-10V but will tolerate up to +/- 25V. Most (all?) of the analog signals are below 5V so the 10V limit on a 12V signal is not a concern. Some outputs and switching signals operate at battery voltage; these are effectively "on" or "off" so these will be treated as logic unless there is a reason otherwise.

I made a list of the signals I want to look at first and was unable to keep it below sixteen!

For long term data collection I am looking at some combination of an AVR128DAxx part, a Teensy 4.1, and a Raspberry Pi 4, for different reasons:
  • The AVR128DAxx can handle 5V and may become the primary ADC for some circuits. The 28 pin version is a DIP so it is easily breadboarded and has 10 ADCs. The 32, 48 and 64 pin versions have tons of analog inputs and can be found on inexpensive breakout boards from the person who ported them to Arduino. So, this may be the default for interfacing to analog pins. On the minus side, it tops out at 25 MHz.
  • The Teensy 4.1 can handle 3.3V but it is programmable with the Arduino environment and uses 600 MHz processor. The support from the manufacturer is excellent, with customized libraries available open source. The Teensy 4.1 has eight serial ports so it is a candidate for handling the RS-422/485 connections. I'm not sure about its ADC capabilities but the 3.3V ceiling is a limitation. It employs high speed USB so between that and the 600 MHz processor, getting collected data to another system is not going to be the bottleneck.
  • The Raspberry Pi 4's primary use is for data logging. Offloading the logging to the Pi avoids timing issues when an Arduino attempts to write to an SD card. With a USB3 interface, vast amounts of fast storage are an option.
I can easily collect volumes of data that will only take up space. I may need to find a happy medium where I am collecting enough information to spot trends or diagnose a problem but have a rolling log that overwrites the oldest data when storage reaches capacity. It may also be useful to collect baselines of data in certain configurations, and perhaps with some common failures simulated to have as a future reference.
 
Discussion starter · #30 ·
Wires added to harnesses to enable observation of any ECM or MCM signal.
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Discussion starter · #31 · (Edited)
An important thing to note is that one can't just connect to any of these signals without risk of adversely affecting car operation. For example, the "ground" for each driver might be a ground reference for DC (unchanging) signals but active signals can put currents on the ground that overlap the signal being measured. Module designers take extra steps to prevent the noise on one subcircuit from influencing readings on another subcircuit. This includes measures beyond the scope of this post. But it means that if a measurement circuit is connected improperly, it can unexpectedly introduce noise into the signal being read by the module and change it.

It's also possible that the device hooked up to a sensor loads that sensor, thereby changing it before it is read by the module. This also can cause adverse behavior. Finally, it is possible to hook up something wrong and break the module.

In other words, the breakout harness made for this project is necessary but far from sufficient. For some of these signals, great care will need to be taken to ensure that the instrument measuring the signal does not change the signal. Therefore, every signal will need to be assessed as to the most appropriate way to capture it without modifying it to the point where the tapped signal causes the car to behave in a meaningfully different way.

So, this will not be a matter of simply wiring a bunch of these taps to an Arduino. In some cases it may require significant accommodations to ensure that the signal being measured is not altered by the measurement circuit.

The largest problem is perhaps that there is no access to the power and ground connections in the module that is necessary to minimize noise. This hopefully underscores that this is not intended for permanent installation but only as a diagnostic tool to identify issues when they arise or confirm continued proper operation during a "tune-up".
 
Discussion starter · #32 ·
My newest Insight diagnostic tool, ready for its first live test:
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Discussion starter · #34 ·
IT WORKS!!!!
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First capture:
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So much stuff to see here!
  • MAP - waveform shows changes in manifold air pressure WITHIN a revolution!
  • (not visible) EVAP - shows low duty cycle...
  • IACV - another potential clue to vacuum leaks at idle
  • NEP - not expected! who consumes this?
  • CKP - I wonder if this can be used to detect misfires?
  • TDC1 - not sure what this sensor does, or if a lobe is supposed to be missing?
  • TDC2 - kinda hard to check my connections - what is this used for?
  • INJ1 - I didn't have enough inputs to capture all injectors. But wow - injection almost a full revolution before ignition!
  • Ignition 1 - 3 - you can clearly see the 1-3-2 timing pattern.
This is only sixteen of the signals. It doesn't include the LAF sensor either. So much to discover! I can't wait until I use it to examine MCM signals! But next is to study these and decide what else is needed.

I designed this to accept plug-in modules which can be used for specific analyses. I think the first module should be a fueling and lean burn analyzer. This will require access to accurate AFR information. I hope to be able to SEE what seems to be misfires and what changes when certain things are done to the car to identify the cause.
 
Discussion starter · #35 ·
that seemed pretty fast even though i can't imagine how much work went into it. does it have a name yet?
"Modular Advanced Diagnostics" or MAD because you'd have to be mad to build something which requires soldering 208 wires and deals with connectors with 104 pins??? It took MUCH longer to build than I thought it would, and building plug-in boards and Python scripts to capture and interpret data will also take a long time.

One of the tasks ahead is to operate it next to my OBD scanner in live data stream capture mode, so that I can convert voltages read by this tool into values provided via OBD2.
 
nice job sean, one thing to keep in mind is the phasing here, i first looked at your screen cap and almost fainted, than i remembered this is dealing with a 3cylinder engine on a 4stroke cycle.

-ckp is crank position- it is crank sensor pointed at a reluctor wheel, all engines ive dealt with this can be substituted for rpm but definately not familiar with 3 cylinder phasing, have to research what type of trigger wheel logic is being used.
tdc is typically cam position.. might be two of them for vtec?
injectors can be fired anywhere throughout the cycle, they are timing agnostic, but this 'phasing' can be altered to get different effects. determining where the factory phasing throughout the rpm band is going to be interesting from my point of view.
early speculation but i would assume at idle and in lean burn the injectors will be sprayed onto the back of a hot intake valve to increase atomization of small amounts of fuel in a low flow port injected scenario. but that is a total hunch.

super cool stuff
 
Discussion starter · #37 ·
i remembered this is dealing with a 3cylinder engine on a 4stroke cycle.
Yes, I had to take a minute to remember that the pistons are oriented 120 degrees apart on the crank! The NEP signal seems to align with ignition rather than RPM!

Here is more to look at. Isn't it awesome to see this stuff at the sub-cycle level?!?!!! (I fixed the TDC2 signal - I had the pin numbers weron conected to the power u

Capture of four seconds of engine start. Engine start at around 0.6 seconds. Note the MAP drop. Note the sensors come alive.

Note the rattiness of the EGR valve position signal --- a clue!
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I'm capturing at full rate which is consuming gobs of memory. The Saleae is only temporary, to help me understand what I am looking at and determine how I should capture and filter the data with the help of a microcontroller.
 
Discussion starter · #38 ·
Here is 1/2 second right at engine start. Looks like NEP is constructed from the two TDC signals. The two TDC signals definitely provide phase information! Note that the idle air control valve is briefly commanded either fully open or fully closed (not sure which).
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At this point the engine has no idea about AFR because the sensor is stone cold. So no point in even trying to capture it yet.
 
im very excited to see where this can lead.
open loop start up..
im sure the ecu has 'start table' which performs different levels of iac and inj pw cross referenced to different coolant temperatures and map values for healthy starts across the entire range of starting conditions.
eg. much more fuel and idle air at colder coolant temps, alternatively it uses less at hot coolant temps, there is probably a specific amount of time that iac tapers into a static state
 
ive yet to see ckp show signs of a 'missing tooth' style of reluctor wheel.. it could be counting teeth for RPM data and NEP could be phasing the ignition timing as the trigger??
really wish i was more intimate with my g1 sensors right now. i'll be staring at my motor until my feet get cold out there.
more data = more better

edit: crank sensor is simple 2 wire sensor counting teeth..
and looking at graphs provided so far, the nep is feeding the ignition coil, i would consider it to be ignition advance at this point in time, this is where a comparison to obd scanner could quickly verify.. hmm
 
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