Data Logging (OBD1 8192 baud) 92 Blazer 4.3l (vin W)

First I want to say thanks to all the people over various forums for all the help and support they have given me on this DIY OBD1 cable project.

I started out thinking I was going to buy a pre-packaged cable from one of the websites that sells OBD1 cables. Because of some ordering mishap the scope of the project turned to making a cable, this is where I am going to say if you have the money IMO just, :::buy a made cable:::

The purpose of this post isn’t really about the do-it-yourself aspect of this project, but for those who want to know what I did to make my cable I will give all the information on how I made mine. All the parts you will need to make a 8192 bi-directional ready cable can be bought off Fry’s electronics website, I’ll post the products I used. I should mention that this is not they only place suitable parts can be bought, so I suggest shopping around. I used Fry’s as an example because I was able to drive there and have my parts on the same day rather than waiting for parts to be delivered.

The ODB1 connector I made from standard connector parts:

FRYS.com*|*WALDOM



FRYS.com*|*WALDOM




I pulled the pins from the header square straight connector, saved the pins to attach to the housing w/ crimp terminal. Solder the pin to the one end of the crimp terminal and some single wire to the other end. I inserted the pin with the attached wire into the terminal house till the pin popped out and the crimp terminal was seated. Note it needs to be inserted backwards to fit. Once I had all the wire inserted into the housing I dropped some superglue on the wire side of the connector to lock it all in place. I know this all might seem a little extreme for a connector, the easy was is to just strip about ½" off a wire and tin it with solder and that makes a good pin for inserting in the OBD1 connector.

For the meat of this cable you have 2 choices depending on what type of port you have on your computer. If you have a Rs232 - 9 pin port then you can buy a TTL to Rs232 adaptor. Here’s the one I bought.

FRYS.com*|*SCHMARTBOARD


This adaptor will need an external +5v source along with a ground. Since my cable is a bit more complex than this I had a +5v and ground source to pull from. Here’s the schematic for the board.

http://www.schmartboard.com/schmartb..._schematic.pdf

J3 is where you connect the +5v and ground, pins 16-15. Pins 10-9 on J2, device_RD and device_TD you combine into a single wire and that will connect to pin M on the OBD1 port. Pin A on the OBD1 port will need a ground to your computer, you can find this on pin 5 of the Rs232 connector of the schmartboard, or whatever TTL to Rs232 converter you use. After that all you need is a Rs232 cable and it’s ready.

If you are like me you’ll need a USB hookup. From the schmartboard I used a Parallax USB to serial converter.

FRYS.com*|*PARALLAX

Drivers for this converter can be found at the Parallax website

Parallax USB to Serial (RS-232) Adapter with Cable



This is pretty straight forward, you plug the Rs232 end into the female D9 connector of the schmartboard and plug the supplied USB cable in the parallax board and the other end in the computer. Since the supplied cable for the Parallax board is USB there is +5v and ground inside. I stripped the micro side connector wire back about 1", found the black and red wire, red=+5v and black ground, stripped them. Spliced in wires then solder it back together. I used the spliced wires to power my schmartboard. End result a franken-cable but it works~ ( The other wires coming from my connector are for the other active pins in the OBD1 port that I might use someday) All you need to Data log is Pin M and Pin A on the OBD1 port.



This post will show pin assignments for OBD1

https://blazerforum.com/forum/1st-ge...-blazer-58972/

Now that I have a cable I need data logging software. I decided to use Tunerpro because it is a free package. For anyone out there looking to data log a 92-94 4.3l vin W you will need to use version 4 of Tunerpro not the current version 5. This is because the definition file used by Tunerpro for this year and vin was written for version 4. I found this out the hard way~ Here is the website for Tunerpro and the definition you’ll need for 92-94 blazer with CPI.

TunerPro and TunerPro RT - Professional Automobile Tuning Software

You’ll need definition file ( A178.ads)

TunerPro and TunerPro RT - Professions Automobile Tuning Software

Version 4 can be found here

TunerPro - Download Legacy Applications

 

I would like to connect with people who can data log their truck. Trying to see what other people are getting for sensor readings. Really hope someone is getting better MPG's than me so I can reference possible improvements.

92 Blazer - 4x4 - 4 door - CPI

 

Did some data logging tonight. This first image shows the truck running at idle, then at the green line, the truck is moving. As you can see the O2 sensor is biased rich during idle and not moving but starts to cycle like it is spose to when it's moving.

Spark advance is running 16-19 at idle not sure if that is right. I have read that 20 is good at idle?



This next image is showing the O2 sensor going flat, lean, during coasting at a speed over 50 mph. Not sure if this is right.



Here it shows another example of the O2 sensor going flat at coasting, you can see the EGR going flat also. If I understand the EGR valve right it is spose to go flat when the TPS voltage is low.



Image 4 is showing where I had the IAC stick after WOT. You can see the huge spike at the end of the TPS graph.



This next image shows where the IAC remains open till I spike the pedal to make is drop back down. This IAC condition only happens with WOT, doesn't happen under normal driving.



So, my questions are, first, should the O2 sensor be biased rich at idle? ALso should the O2 sensor be going lean during coasting at highway speeds? And what could be causing the IAC to stick after WOT, and not during normal conditions?

thanks~

 

ummmmm......

 

I have a '95 w/ CPI. It's OBD1, but has the OBD2 type connector. I bought a cable from here: OBD Diagnostics, Inc. - ALDL (GM OBD1) Cable with 16 pin Connector
They suggested Tunerpro RT. I've only messed with it a little bit, but haven't gotten the truck and the laptop to talk with each other yet. I'm pretty sure the cable drivers are installed properly, and the software is set for the right com port. How did you figure out which version to use? Tunerpro is a little more advanced than what I need, but it does look interesting.

 

Did you get the 16 pin to USB port? I got a 12 pin to USB port from the same company. After many many emails to both the owner of RT and the cable company (they even sent me another cable to try) I decided to load up another software just too see if it was my PCM or the software or cable. This software is $120 but they give you a trial period to test it. On the software I found this:

NOTE: TTS has found that most USB-Serial adaptors fail to operate correctly due to the ALDL baud rate requirement of 8192 Baud. These adaptors ‘appear’ to be operating correctly but will not communicate with PCM. For this reason, it is recommended that the TTS USB serial port adaptor be used, as this is tested with all Windows versions.

Great... I'm going to send back the two USB cables and ask for a 12 pin Serial port connector. Will let you know what happens if your interested.

 

Here's what I know about serial to USB chips...

The FTDI chipset seems to more compatible, or robust with ALDL communication ports. The Parallax serial to RS232 adapter I am using has the FTDI chipset, and the RS232 to TTL adapter I am using has basic Max232 chipset, both have been proven to work with the OBD1 port. I have also tried using a TTL to USB all-in-one cable, it has a Prolific chipset and failed when tried with both Tunerpro 4 and 5. I recommend that any cable you purchase has the FTDI chipset and a MAX232 or equivalent.

As for which version of Tunerpro to use, well in my case I had to use version 4 because of the definition file. But, with that said, I would use the most current version if there are current versions of the definition file for your specific car or truck.

Reference link to the FDTI
http://www.ftdichip.com/

Magmotor, did the second cable work? Did a different software package work?

 

Got the new cable and 'nope' didn't work..... also tried the TSS DataMaster software and same thing.....I've been on the phone with these guys for the last 2 weeks, geat company to deal with, they will try anything to help.....so, i'm sending back the two good USB cables and they're sending me the RS232 serial cable.....gotta a feeling that ain't gonna work either but what the hey...will be the last try on this....crusin down the hwy 4 days ago and wham...engine just shut off...nutten...coasted to the side of the hwy....checked under the hood for ignition coil wire came loose or sumpton....nothing...tried to start it..nutten...was getten the cell out to call a tow truck and decided to try one more time and varoooommm...started right up.... so, yesterday I replace the 18 yr old coil with a new MSD system....we'll see what happens, hope it's not the PCM checking out on me.....will let you know on the new serial cable.....