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This is where it will all begin - to be followed by many more episodes. I'll explain:
20 years ago, they made our version of the 7.3L - based on engineering going back much further. Thinking that through - our base engine/electronics was engineered pre-Windows 95, pre-Ipod, pre-smartphone, pre-Google, and you had to pay big dollars as an extra to get sound on a computer. My oldest son was in high school with a breaking voice (as were many of our mechanics), and now my grandchildren are sneaking up on junior high.
"Where's Tugly going with this?" you might ask. Today's mechanics are more of the "The computer says to replace X" variety than they are the "Lets take some readings and figure this out." variety. "Why?" you might ask. Well... they were raised with computers giving the answers - where many of us were raised at a time when computers were big, expensive, and really didn't have much to offer us - unless we liked spreadsheets. The punchline is... our PCM computers are from that era - so they don't offer up a signed confession of guilt, with a selfie video of the part failing.
In answer to this dilemma, I am starting the Paramater IDentification (PID, or sensor/control) reading class that's akin to palmistry - it'll be about reading the lines. When I say lines, I mean many people now have OBDII apps that can log PID readings. When we chart multiple readings of the same PID over a period of time, we can make a graph by connecting a line between each reading. This line can show a "behavior" in a vehicle, as opposed to one reading of one PID - which is about as informative as a facial selfie of Kim Kardashian... unless she's in front of a mirror and you can see her backside.
That was about as clear as mud, so I'll get graphic here. Say somebody with an automatic logged on and said "My engine temperature is reading 300 degrees." My answer sounds a bit odd, but what the poster describes is perfectly normal and no harm, no foul. If one were to log the Engine Coolant Temperature and the Engine Oil Temperature as the engine warms up, the different temp readings over time will have a line drawn through them and we can see a trend.
As you can see, the Engine Coolant Temp (ECT) is really high, then it falls abruptly, then it starts to climb again. The Engine Oil Temperature (EOT) climbs gradually as one would expect. The answer is the ECT is not read by the PCM on an automatic - that connection on the PCM is tied up by the Transmission Fluid Temperature (TFT). Think of it as call-forwarding - the PCM calls one place but gets another. "OK Tug. So... you say the TFT is sent to the PCM via a connector for the radiator temperature. What is that weird line for Engine Coolant Temperature?"
Easy... the PCM is "winging" it. The PCM has no clue what that sensor is saying, but you're asking for an answer when you select that in an app - as would anybody who has ever driven and had an engine temp gauge on a dash. The PCM then takes some readings of other stuff within the truck, applies a little math to it, and spits out some bogus answer as the ECT PID. I find the big dip interesting, because it happens at an Engine Oil Temperature where the PCM changes a lot off parameters in the tune. So... only trucks with manual transmissions can read ECT, and those with automatics should use only the EOT to get the engine temperature.
I like this. Now we have to figure out how to put late model injectors in our 7.3 with a PCM that will work. Oh and 4 valve heads! A good write up Rich. Just play an. Would be nice though.
I thought about this being a one-stop source, but the thread would explode in growth like the AE thread did - making it near impossible to absorb. With that in mind, I won't cover app settings in this - just how to deal with the data collected by whatever app is used. App settings can be covered by another thread, and apps will change over time anyway (like AE did). I hope the information in this series of threads is as stable (unchanging) as the design of our trucks. Episode 2: [LINK] Episode 3: [LINK]
I have in my possession OBDII logs from many vehicles with the 7.3L - I've been collecting them for a few years. ExPACamper (John), white Buffalo (another Rich), and I have been working on an "app" of sorts that can be downloaded to turn logs from OBDII apps into readable graphs. John is the star of the show in this one - he's the code writer. Rich is the beta tester and he provides feedback to John to tweak the product, and I've been little more than a consultant. Rich and John have put a lot of hard work into this.
Now... in this graphing product is a little math I worked out that can instantly indicate when something is amiss with the fueling. It doesn't scream "Replace your HPOP!", but rather... it says "That's odd - you're not getting the power you should because of a fueling issue. Maybe you'd like to look deeper into this - and don't overlook your tuning if it's not stock." What this should do is help those who don't really know what to expect from their engine... even if it has a chip in it.
None of this happened overnight - it has been a project off and on for over a year, as the three of us have time to tinker with it. I just got the latest version uploaded to my own personal "cloud server" yesterday (I have full possession and control of the device on the net 24/365). John just learned of a new app he can utilize to make this whole thing easier for the masses to use.
In a nutshell, we've been getting ready to share the logs for comparison, and the app as the tool to compare them. This series of threads is a primer, so that when everything is available - you will all have something as a reference to understand what all the pretty and colorful squiggly lines really "mean".
Torque Pro (and a few other OBDII apps) start up in whatever default setting you programmed in. In my case, default is "Stinky", with 12 gauges and a clock. I also have another profile - "Stingy" (the Prius) - which has a gabillion gauges just for the battery pack.
The deep answer:
The software scans the truck and finds available PIDs, plus you can program a PID directly if you have a source for the code information. The tricky part is the formula in each PID. The PCM doesn't send out a voltage - it receives a voltage or other signal from each sensor and converts that to a digital signal that the app can read. The PCM also does this for key commands - like IPR, transmission gear, FIPW, etc.... The app then has to convert the sensor/command signal converted to a digital signal and convert it to something we understand - like PSI or KPA, degrees F or C, MPH or KPH, etc.... Converting to "human" language is where we have to put in a formula (mathematical equation) for the information to be accurate.
Those formulas have been worked out by people with separate temperature and pressure sensors, or with apps that already have the correct readings. It has been a form of reverse engineering to date, but it's my understanding the information that we've been struggling with is now sneaking out from under the cover of copyright. I've heard a rumor that car manufacturers have had to release the OBDII "enhanced codes" on the earlier OBDII vehicles.
Many people use their OBDII app for making graphs (if the app makes graphs), and I do that as well... but.... When it comes time to analyze the data for troubleshooting or for presenting a legible graph to the forum, I've been using OpenOffice Calc (a spreadsheet program).
Things are changing. John has been writing macros (tiny "programlettes" within a program) in Microsoft Excel (another spreadsheet program), and OpenOffice has never supported the Microsoft macros. I recently learned OpenOffice split into two "factions" and the heavy talent (programmers) went to the second project - "LibreOffice" [LINK]. Given "libre" is latin-ish (Spanish and French) for "free", I don't think they have a bait-and-switch in mind.
In short - LibreOffice supports macros, has updates at a rate of 14:1 when compared with OpenOffice, and appears to be more universal than most other office suites. I still have to test the macros to confirm the claims, but I had no problem using LibreOffice to fully modify the graphs made in Excel and OpenOffice. The viewer work in Android, and the full editor is "under construction", but I have no word yet on iOS. If you are looking for a cross-platform office suite that works with macros, I hear tell WPS Office is your product.
12-24-2016, 10:02 AM
