Help interpreting ALDL data

[Second Series]

Do these numbers look good? I haven’t driven the truck for a couple years. None of the gauges are connected and the check engine light is not connected so I wanted to see how things check out.
I made an ALDL cable to connect a computer to my ’88 k2500. The cable is based on instructions I found on the web. I have an older laptop with the DB9 connector. In my haste to build the cable, I put in R4. I installed WinALDL to my laptop, and tried it on the truck. It didn’t work so I removed R4, but still didn’t work. I checked R2 and saw 6v from the pc and 2v to the transistor. I added a 12v line and moved R2 to that. It still didn’t work, so at last I tried a different Baud rate. There are only 2 Baud rates in the software,2400 and 4800, the higher one worked.
I ran the datalogger and it saved to a text document. The header line wraped around to two lines, and the data columns below were hard to match to the header. I selected all and pasted to a spreadsheet where everything went to the correct place. I’m not sure what to do with all that data. There is also a live window that they caution against looking at while driving. The live window converts the raw data to tanguble values. I still don’t know what to do with these numbers though. There is also a dash display that is easy to use that includes speed and RPM.
I’m thinking it wouldn’t be too difficult to build a dedicated digital display for the speedometer and tachometer.
I was looking for a connector for the ALDL. I did find the female connector as is in the truck. I contacted the vendor and they sent a technical request to the manufacturer as to what the male counterpart is. I’m still waiting for a reply. I only used 2 wires to the ALDL and a third wire for 12v, but a connector would be nice.

[ChevyTech]

The numbers show it is not up to operating temp and is running in open loop where the system runs off the program instead of the using the oxygen sensor to control the fuel mixture.

The battery voltage is to low. It looks like the alternator is not working at all.

[Second Series]

Thanks for the reply ChevyTech. I removed a dual battery block and used my '90 k1500 as an example. The '90 only has one wire at the alternator connector. The '88 had 2 wires with one going to the dual battery block, I simply cut it out so it's wired like the '90. I'll connect that other wire, I think it's the voltage sense according to this post: https://67-72chevytrucks.com/vboard/....php?p=8154775
After I get the alternator working, I'll get the truck up to temp and take some more readings.

[special-K]

I'm glad you got the help you needed. Chevy Tech has been a big help for many including me!

[Second Series]

Originally Posted by special-K

I'm glad you got the help you needed. Chevy Tech has been a big help for many including me!

Agreed, I have read many posts by Chevy Tech. I read more about the alternators for these years. I haven't found a schematic for the gauge cluster, so I'm not sure what the L key power wire goes to, I'm guessing the alternator gauge. I saw that it can be connected to a light, or a resistor to key power if the original cluster is not used. I have cut some wires on the cluster connector and wired in a DRAC, but I was able to plug in the original cluster for the L load and to get some gauges for now. I just need to find the time to connect the voltage sense wire and get some more ALDL readings. I'll post here when I do.

[Just call me Sean]

The two center wires of the alternator plug are to power the alternator. One is used if you have a gauge, the other is used if you have a light. I learned that when I was gathering parts for a dual alternator conversion.

[ChevyTech]

Thank you for the kind comments guys!

[Second Series]

I found some time and was at it again. After connecting the sense wire to the hot line, the truck would not start. I wiggled the cluster connector and it fired right up. This truck has an alternator light that came on for a moment when it started, and there is the alternator gauge that was at about 14v while running. I’m guessing the alternator light came on because the battery was low. I don’t get that light in my ’90 k1500. I got it up to temp, I could see the temperature cycling through the winaldl. Currently no error codes, but I haven’t driven the truck. Here are the readings:

[ChevyTech]

The alternator looks to be charging now.

The IAC count at zero means it has lost control. It could have a vacuum leak.

Temp at 180.2 is low for this system. 189 is the threshold to run some self tests. Factory T-stat is 195 degrees.

The integrator and block lean are still not moving. It may still be to cold.

TPS @ 3.1% indicates it is not at idle. If you pushed the gas pedal to start it, that can mess with the TPS readings on this system.

[Second Series]

I’ve been busy. The battery died, so I have replaced it. I found a vacuum line to the charcoal cannister disconnected so I hooked that up. It was a hot day yesterday and I ran the truck for awhile, but it is not reading over 183 degrees. I’ll see if it gets higher when I drive it down the road. It may be awhile before that happens since it needs the glass and latches installed.
The WinALDL window has 9 tabs; Help, Raw Data, Flag Data, Sensor Data, Error Codes, BLM, INT, O2, Spark Counts.
Here is a screen shot of the Sensor Data, and Raw Data. I also recorded the Log Data and placed it in a spreadsheet. I started the Log capture before starting the engine, with the engine hot. It idled somewhat low until I gave it some gas.
I could see some values changing in the Sensor Data tab. The TPS, and IAC changed as I stepped on the gas pedal.
I see I can't attach the spreadsheet...

[ChevyTech]

The data show the system is running in open loop meaning the system is not using the oxygen sensor to adjust the fuel mixture. It looks like it is to cold to get to closed loop.

The IAC count is low.

TPS reading which fits with the IAC count making it look like the throttle stop screw could be holding the throttle to far open. Also notice the percentage reading for throttle opening is not zero, which I am noticing on another thread with WinALDL. It could be a fluke with the software.

[Second Series]

Here is the Data Log. I started the log before starting the engine, engine hot. I did not touch the gas pedal at start up. The idle was 500rpm, I goosed the gas at T107, and the idle went to 875rpm.

[ChevyTech]

The system is in open loop so it is not using oxygen sensor data to adjust the fuel mixture.

The coolant temp is below the threshold for multiple ECM functions.

The inactive oxygen sensor reading fits with it being to cold.

The IAC is not in the range I would have it. It is close to losing control.

[ChevyTech]

I did some reading on using WinALDL

I have never used WinALDL myself but have helped people on the message boards that are using it. After looking at data readings that seem so wrong I did some searches and reading on using WinALDL.

After reading on the http://www.winaldl.joby.se/ site I see the user has to make choices on how the data will display. Go to that site and click on the Click here for screenshots and descriptions of the different data displays link.
The user must make choices for how the TPS (Throttle Position Sensor), RPM (Revolutions Per Minute) and MAP (Manifold Absolute Pressure) sensor data will be displayed. Now I realize why the data logs the people a posting have readings that look so screwed up in these data sets.

The user can also chose to display the data in US values rather then metric..
The user can also pick which data will show.

I read much of the version history during development and saw Nov 14 2001 changes were made on how the TPS data is displayed. This may have been when the choice selection was added in the display choices. I have noticed TPS irregularities in the logs people have been posting so they are most likely not setting things up correctly, or not realizing they have a choice to make.

My conclusion is that this software is great for an experienced person that has time to work with it and get to know the quirks of it, but for a newbie it is not going to be as easy as using a good scan tool.

If I was using this software I would establish my TPS voltage with a multimeter before using the software to know what to put in the choice boxes that control how the data is displayed. The RPM and MAP also has choice boxes which raises more questions.

[Second Series]

Thanks! I'll look into that info and use WinALDL some more. I'll take some readings from my '90 k1500 that actually drives.
I'd like to know what you are looking at in the data that tells you the system is in open loop?

[ChevyTech]

Originally Posted by Second Series

Thanks!

You're welcome!

Originally Posted by Second Series

I'd like to know what you are looking at in the data that tells you the system is in open loop?

The INT & BLM are setting at 128 which tells me the system is not trying to adjust the mixture at all.

The system will not go into closed loop with the oxygen sensor voltage setting as still as it is.

You can go in and pick the data it will show so it displays the loop status.

[Second Series]

In order to decifer winALDL an understanding of what is happening is necessary.
I have been reading about the ALDL and the EFI system. I have summarized some of that here.

There are three operating modes, Closed loop mode, Open loop mode, and Power Enrichment mode.

The engine runs in Open loop mode when it is started, when idling, or when engine load increases. The O2 sensor is ignored. In open loop, the ECM commands an A/F ratio that is determined from a table of A/F vs. engine coolant temperature.

In Closed Loop, the PCM takes dozens of readings from the O2 sensors each second and uses that data to fine-tune the amount of open time the injectors are on. The MAP, Temp, and RPM are used to make a base fuel guess, then the O2 sensors give the PCM feedback on how well it has guessed, and it adjusts to maintain an Air/Fuel ratio of 14.7:1. This is the value that allows a catalytic converter to reduce exhaust emissions most efficiently. This is also the value that typical O2 sensors are most accurate at. O2 sensors start to work above 300 degrees or 600mv. The A/F has a value of 1 in the equation during Closed loop mode.

Power Enrichment mode is with wide open throttle. The O2 sensor is ignored and the TPS is used to determine the A/F ratio.

There is an equation used to determine the Base Pulse Width of the injector.
BPW = BPC * MAP * T * A/F * VE * BVC * BLM * DFCO * DE * CLT * TBM

Let’s look at how this equation relates to the values in winALDL.
winALDL shows several readings. IAC, Coolant Temp, Speed, MAP, RPM, TPS, INT, O2, Battery Voltage, Knock counter, BLM, rich/lean to name a few.

BPC, Base Pulse Constant is calculated from the volume of one cylinder, the flow rate of one injector, and a constant.

MAP, Manifold Absolute Pressure, that value can be seen in winALDL.

T in this equation is the inverse of the absolute temperature.

A/F may be the O2 reading in winALDL. (The value that I got at idle was around 0.45).

VE, Volumetric Efficiency, VE is an important factor in the equation that corrects for different engine efficiencies. It is based on a table of RPM and MAP conditions. This table can be modified to tune the chip.

Battery Voltage Correction. This term is a correction to offset the change in injector response due to battery voltage fluctuations.

The BLOCK LEARN term can be viewed as a semi-permanent automatic adjustment of the VE tables. If you disconnect the battery, the BLM adjustments revert back to 128 or neutral (the neutral value for a BLM value is 128). Another name for the BLOCK LEARN term is long term fuel trim. Over time, the BLM numbers will settle at a value that gives a 14.7 A/F ratio with no closed loop term correction. There are more than one BLM value, unlike the single Integrator. The BLM can be up to 32 different numbers depending on the ECM model. The Block Learn term derives its name from the way the VE table is divided into blocks for the corrections to take place. A cell value of 128 is neutral, no fuel is added or subtracted. A cell value below 128 is rich, A cell value above 128 is lean. (The value that I got at idle was 128 and that indicated it was in open loop mode).

INT is shown in winALDL. In closed loop, it is discussed how the Integrator increases or decreases as the ECM gets feedack from the O2 sensor. The BLM value tracks the Integrator but has a delay. If the Integrator increases, so does the BLM, but the BLM lags behind the Integrator. The higher the Integrator climbs above 128, the faster the BLM rises. As the BLM rises, it begins to effect the AFR because the VE table is being increased. As the AFR drops (gets richer) in response to the increased VE table, the Integrator will stop rising and begin to fall. Once the Integrator returns to a value of 128, the BLM will stop moving. Not only will the BLM stop moving, it will remain at that value permanently, essentially retuning the VE table at this engine operating condition.
If the BLMs are both above and below 128, but not too far above (135) and below (120), your VE table is probably reasonably close. If your BLMs are way above and below 128 all over the VE tables, the calibration is probably significantly off and needs to be manually corrected in the chip with an EPROM burner.

DFCO, DECEL FUEL CUTOFF. When you take your foot off the gas pedal going downhill or decelerating quickly, the ECM will cut off the fuel entirely.

DE, DECEL FUEL ENLEANMENT allows some fuel to continue.

CLT, CLOSED LOOP, or short term fuel trim is when feedback from the O2 sensor is used to make corrections to the air fuel ratio. The ECM makes immediate but temporary corrections to the fuel delivery to maintain the AFR at 14.7. The short term fuel trim value is called the Integrator in most early scantools. The value of the integrator varies above and below 128 with 128 being no correction. For ex., if the Integrator is 140, the ECM is adding fuel because the O2 sesnor is reading a lean mixture. If the Integrator is 115, the ECM is removing fuel because the O2 sensor is reading a rich mixture. Anytime the system is not in closed loop, the Integrator will immediately return to a value of 128 and stay there. There is only one Integrator and its value is solely dependent on the O2 sensor. When the engine is started, the ECM will keep the Integrator at 128 until the ECM determines that the O2 sensor is working correctly and that the engine temperature and time delay constraints before entering closed loop have been satisfied. Once the ECM goes into closed loop, the Integrator begins to adjust the fuel delivery to maintain a 14.7 A/F ratio, however, the Integrator term is only weighted half as much as the Block Learn term. The Integrator and BLOCK LEARN work together to re-tune the system to match any engine's charactersitics, up to a practical limit.

TBM, TURBO BOOST MULTIPLIER is for when a turbo is used.

Because of the slow data rate, 160 baud, the O2 sensor voltage is meaningless unless it shows stuck at the same voltage all the time. The normal behavior of the O2 sensor is to cycle rapidly, 2-3 times a second, from rich to lean.

The biggest benefit to WinALDL aside from the normal scantool functions is to log data while driving, particularly the BLM and INT numbers. Over time you can begin to see rich or lean conditions at various throttle/load conditions, and if they're significant you can modify the fuel tables in a new chip and tune your motor that way.

I wish there was a source for this information, but it is just what someone said on the net.

I found most of this on sites about tuning or setting up EFI on an originally carbed engine. The first step is to make sure the timing is correct, use a timing light. The next step is to set the minimum idle, disable the AIC during that procedure. Measure the min and max TPS voltage with a volt meter, plug these values into the boxes on the Configuration page of winALDL. With the correct ECM Type, Com Port, and Baud settings data should flow. There are only Two options for Baud rate, 2400 and 4800. My truck is a 1988 model and supposedly 160 Baud, but my winALDL works with the Baud rate set to 4800. I’ll use the default settings for RPM and MAP range for ‘Narrow’ until I see a reason to change these.

Now it’s time to log some data. The truck should be at operating temperature. Turn on the data logger and drive for 10 to 30 minutes or longer. I had my data tabs set to Narrow Latest, I think Wide Avg might be a better option. I’ll try some different settings. After driving for awhile the BLM, INT, and O2 grids should be full of data. That is what you look at to determine if anything is off and what to change to tune a new chip.
My ‘88’k2500 project is not on the road, so I’ll wait until it is to log data there. I do have a ’90 k1500 that will work as a test subject. I just need to find some time and get it done. I’ll post some logs when I can get to it.

[hatzie]

Originally Posted by Second Series

Agreed, I have read many posts by Chevy Tech. I read more about the alternators for these years. I haven't found a schematic for the gauge cluster, so I'm not sure what the L key power wire goes to, I'm guessing the alternator gauge. I saw that it can be connected to a light, or a resistor to key power if the original cluster is not used. I have cut some wires on the cluster connector and wired in a DRAC, but I was able to plug in the original cluster for the L load and to get some gauges for now. I just need to find the time to connect the voltage sense wire and get some more ALDL readings. I'll post here when I do.

If you need the 88-93 wiring diagrams you'll find them in my signature.

[Second Series]

Originally Posted by hatzie

If you need the 88-93 wiring diagrams you'll find them in my signature.

Thanks hatzie! I did find the wiring diagram there a couple years ago and added color. It has helped me modify several systems. I did not find the schematic for for the gauge cluster pcb. If you know where I can find a diagram of the gauge pcb I would appreciate it. Everything I have seen shows up to the cluster connector with the pins labeled, but there is a lot going on on the circuit board.

[ChevyTech]

Originally Posted by Second Series

... I did not find the schematic for for the gauge cluster pcb. If you know where I can find a diagram of the gauge pcb I would appreciate it. Everything I have seen shows up to the cluster connector with the pins labeled, but there is a lot going on on the circuit board.

Look in thread hatzie posted for his GMT400 CK Service Manual project.

Open the PDF that is the third manual down in the 1988 section:
1988_ST-375-88-EDM_GM_CK_PICK-UP_TRUCK_ELECTRICAL_DIAGNOSIS_SUPPLEMENT.pdf

The instrument panel information is found here:
Per page numbers in manual 81-0 through 81-15
Per page numbers in the PDF document viewer I us shows page 144 through 159

Page 33-0 in the manual or page 78 in the viewer show some of the DRAC in the instrument panel.

There is not a good complete schematic of the instrument panel anywhere that I have found that shows the DRAC and everything thing else going on in there as you said there is a lot going on in that instrument panel.

I looked at your 47 panel frame swap thread. I saw you mention the DRAC. I have a lot of information saved for recalibrating the DRAC so if want jumper selections let me know.

[Second Series]

This is great! Thanks! It confirms there is a resistor in parallel with the volts indicator. It will also help me with adapting discrete gauges to the stock wiring. I have a DRAC wired in, and have a couple charts for figuring the ratio jumpers. That will have to wait until I’m done with redisigning the mechanical speedometer drive.
Back to the winALDL.
I ran WinALDL on the way home from the hardware store. I started the Datalogger and then started the truck. This is a 1990 K1500 with the 5.7 v8 and 5-speed manual transmission. I made the ALDL interface and used an older laptop with the RS232 port. I noticed the computer monitor went dark halfway home, I’m not sure if the battery got too low, or if it went to sleep.
There are 82 columns in the data log. The first column is Time it is in seconds. The next 20 columns are RAW data, followed by 13 columns of Sensor data. Then there are 8 columns named MW2:… such as MW2:ALDL Mode (10k Ohms). 8 columns of MWAF1:… such as MWAF1:Closed Loop Flag. 8 columns of MCU2IO:… such as MCU2IO:TCC Locked. The last 24 columns are named MALFFLG… such as MALFFLG1:23 IAT / MAT low (Air Temperature). I’m guessing these are for a Malfunction Flag? They are all zero for this run.
In the spreadsheet, I hid all the columns that I don’t want to look at. I highlighted all the rows that the closed loop flag = 1. The first thing I notice is the Air Divert Solenoid ON flag is opposite the closed loop flag, so the Air divert solenoid is On during open loop mode. INT is at 128, or neutral during open loop mode.
I hit several red lights, and it looks like it goes into open loop mode each time.
I measured the TPS with a multimeter and used those values in WinALDL, .59 to 4.38. The TPS column shows -1.1 to 23.2(I didn’t floor it). I’m not sure if the negative value is valid, the RAW values are 28 to 75. There is probably a difference between what my DMM reads, and what the ECU reads.
Closed loop flag and BLM enable flag go to 1 after 45 seconds, temp at 190 and 6mph. After the initial closed loop operation it looks like it goes to open loop when the speed and TPS drop, and to closed loop mode when th IAC and TPS increase.
I’m not sure what to make of the array tabs for BLM, INT, and O2. I’d like to get a tuner program and see what the config is for this PROMID 9481, something to compare to. It doesn’t look like I can attach a spreadsheet here, so I will attach a text document of the data log. You can select all and paste into a spreadsheet if you like.

[ChevyTech]

What is showing in your post looks ok. I could not see how the attached file was organized.

A 1990 K1500 TBI truck does not have a IAT or MAT sensor.
Does the truck have California emissions or federal emissions?
A 1990 federal emissions K1500 truck does not use a Air Divert Solenoid.

When I was looking around and reading about WinALDL logging several people had TPS readings that were slightly negative at idle. People were commenting on it. It seemed to me it had to do with the requirement for the user to install parameters for the TPS when using WinALDL.

[Second Series]

Originally Posted by ChevyTech

What is showing in your post looks ok. I could not see how the attached file was organized.

A 1990 K1500 TBI truck does not have a IAT or MAT sensor.
Does the truck have California emissions or federal emissions?
A 1990 federal emissions K1500 truck does not use a Air Divert Solenoid.

When I was looking around and reading about WinALDL logging several people had TPS readings that were slightly negative at idle. People were commenting on it. It seemed to me it had to do with the requirement for the user to install parameters for the TPS when using WinALDL.

The text document of the data log is hard to read. If you select all and paste to a spreadsheet it aligns the headers to the columns. I used the MALFFLG1:23 IAT / MAT low (Air Temperature) as an example of how that dataset is labeled, it was all zeros for this truck. I noticed there were some flags thrown for TCC locked, but this is a manual transmission truck. Maybe the ECU spews a broad dataset and each truck configuration uses what it needs?
I decided to try something different. I set up an RS232 to usb convertor and used a newer laptop with usb port only. I measured the TPS through WinALDL on the Sensor Data tab with the key on, engine not running, foot off the pedal, and pedal to the floor. I plugged those values into the configuration window. That got rid of the negative TPS readings and it was easier than probing at the connector.
Again, I started WinALDL first and then started the engine. This time I wanted to start cold. I started driving and it went to closed loop after about 3 minutes, the coolant temp was only 135, but I was going 42MPH.
There appear to be times when the Closed loop flag is 1, but the TPS is near zero and the INT is held at 128 charachteristic of Open loop mode. It may be that I wasn’t stopped long enough to change modes.
I’m getting more familiar with understanding the output of WinALDL, I’ll run a few more times to get more examples. This truck runs o.k. There is an exhaust leak and the has an oversized air filter element, something the previous owner did. I’m not seeing anything in the data log that points to that, so I am no expert.

[ChevyTech]

I got the Run2aldl2 file opened in a spread sheet and it looks good.
The only thing to mention is I expected to see the knock count climb. Some knock counts are normal.
If the system did not get knock counts when it ran a self test it would have set a trouble code.

I also went back and got the Run1aldl file open in a spread sheet.
I just gave it a quick look and noticed the IAC count hit zero on some frames of data which you never want to happen.

[hatzie]

Originally Posted by Second Series

I was looking for a connector for the ALDL. I did find the female connector as is in the truck. I contacted the vendor and they sent a technical request to the manufacturer as to what the male counterpart is. I’m still waiting for a reply. I only used 2 wires to the ALDL and a third wire for 12v, but a connector would be nice.

The handheld Bosch 1300 diag tool uses adapter pigtails with standard density Female DB15 connector to 12 terminal GM ALDL, EEC-IV, SCI, and both Toyota proprietary diag connectors.
You may not get all 12 terminals passed through in the Bosch 1300 tool cable. I'd ask.
https://www.ebay.com/itm/225053949859

I have an old Autel code reader for diag on pre OBD II vehicles. That tool has a male GM ALDL plug to some kind of D-Sub connector.

Another option is using cabling in your complete Tech2 setup if you have one.
The complete Tech2 kit has a 12 terminal Male Metripak 280 ALDL plug to female round 19 terminal connector that plugs into the Tech2 VCS cable.
The Tech2 VCS cable has a high density female 26 terminal D-Sub connector to male round 19 terminal plug.
I have a complete Tech2 and I buzzed out the ALDL adapter with my meter. All 12 terminals are connected to terminals in the round female connector.
You'll need a male HD 26 terminal D-Sub connector to mate with the VCS D-Sub.

I've seen one overmolded ALDL plug with an un-terminated cable advertised. I haven't ordered from them. Someone is making them or was.
http://obd1.com/products/daewoo.asp