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FAQ-Data Logging

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Bill USN-1

F.I. Moderator
You will then need the cable to log your data from your ECM while you drive. I use winaldl And the 1 transistor cable. see bottom of page All the parts from radio shack cost about $6
you can also buy a preassembled cable from Jeff. fuel injection aldl cable w/ usb port - IH Parts America

160 baud aldl hardware interface
the ECM produces the data signal at either a 12 volt or 5 volt level that must be inverted and converted to rs232. One simple scheme is to feed the aldl data into a single transistor level converter that inverts the data to produce a pseudo rs232 level (varies between 12 volts and 0). This is connected to the receive data line of a serial port to be processed by the pc's uart.

jumper is installed at the aldl connector for diagnostic modes.

not used for 7747/8746

The aldl cable does not include the aldl connector. That will be mounted where ever you chose. I just keep mine in the glove box.

All you do is use a couple 1/8 spade terminals or simply tin the ends of the wire and put the ground in "a" and the serial data line in "e"

The diagram shows the pin numbers from the back where you connect the wires.

This pic shows the db9 serial connector with the numbers on the front face of it, just in case you get confused.

Here is what it looks like assembled. It all fits in the db9 serial connector.
Or you can make the circuit on a little bread board in line on the cable.

You only need 2 wires to log data!!

if your laptop does not have a serial port then you will need an usb to serial adapter.

I have used the pcmcia to serial cards.

And I currently use the io gear guc232 cable.

Normal price is $32.95

do not buy a cheap usb to serial adapter cable unless it comes with the driver disk!!!!!
They will not work!!!!!


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buy this one and remove the r4 resistor!!!! ;)

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Bill USN-1

F.I. Moderator
To log data you will need software. For the basic 88-91 GM 1227747 we use winaldl And the associated cable like the one shown at that link.
When you first open it make sure you set the configuration to the 1227747 ECM and your com port selection shows ok.

There are basically 2 files I use when logging data.
1 is the blm log. This is the block learn mode or a table log that shows how much adjustment the ECM had to make to the main fuel table to keep the engine at 14.7:1 afr(stoick). The optimum being 128 since each cell goes from 0-256. If the logged number is higher then 128 the ECM had to add fuel because it's lean. If it's lower then 128 the ECM had to remove fuel because it's too Rich.
Note I have wide avg selected in the lower right corner.

The other file I use is under the data logger button.
There are several boxes to check. Check all except the raw box.

Now we have the basics so all we need is data.
You need to take a drive for at least 30min making sure you cover most driving styles from idle to wot-wide open throttle, city and highway. The more cells you log data in, the better.

When the drive is done, before you turn off the key, on the blm page hit save table. This will save the file in the same directory where you installed winaldl.

For the blm data you can simply open it as a text file. Something to note is the 100 map column will not be lined up in note pad so you must delete 2 spaces from that line for proper alignment. I take the space out on each side of the forward slash between rpm/map.

Here is the wide avg blm data that was logged.
There are numerous tables logged. I primarily use the wide avg, number of sample and the error corrections at the end.
You should have no less then 5 samples in a cell to be able to get a valid average of the data.

And when opened in notepad.

The other file to save is the data log. Simply hit stop on the small window and it will save the file in the same directory.
All files have a date and time in the file name so you can tell when it was saved.

Next-what do you do with the data?
Depends on wether you are running it as is or if you are burning a new chip.
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