Logging wideband O2 with stock PCM and Datamaster – WRITEUP

Hi there,

Since I have not seen or heard of any actual information on how to log WBO2 signal thru the stock PCM with Datamaster, I decided to share my knowledge and do a “tutorial” kind of writeup on this subject, the way I have made it to work.

Please note, that I don’t take any responsibility for this information, and this is applying to the Innovate LC-1 wideband setup, which has a linear, programmable 0-5V analog output. If you have a different WBO2 controller, you should check for these features, and you should recalculate the equation below with the relevant AFR vs Voltage figures.

The purpose of this project is to log RPM and other relevant engine data with WBO2 signal at the same time, in the same program, so it would enable to plot a synchronized AFR vs. RPM table for WOT fueling calibration.
There are different ways to log these parameters with so called “aux boxes”, but since I was too cheap to buy the extra (and way overpriced IMHO) rpm signal stuff, and didn’t want to deal with too much extra cables and connections, I decided to give it try thru the stock PCM.

So, here’s a list of equipment you will need:
- OBDI ALDL cable (from akmcables.com or moates.net)
- Datamaster EE from TTS (a trial version can be downloaded at ttspowersystems.com)
- WBO2 controller with programmable, linear 0-5V analog output. (your choice)
- computer (obviously)

We need to feed the 0-5V output of the WBO2 controller to a 0-5V analog input in the PCM. The best choice is the A/C pressure sensor, since it is not used for normal engine operation, and most of you have probably already deleted A/C.
After you have wired in the wideband controller and it is fully working, hook up the wideband controller analog output signal wire and the analog output ground wire to the relevant A/C pressure sensor connectors. The unused sensor connector can be used for a really clean install.

Now comes the tricky part. If you check it in Datamaster, the A/C pressure field will show PSI values which we’ll need to convert to AFR. According to the datastream information for ’94-’95 LT1 F-cars, byte #30 is for A/D RESULT FROM A/C PRESSURE TRANSDUCER. This byte reports raw data called “N” which we’ll need to convert first to Volts, then to AFR.

Conversion function according to the datastream information is VOLTS = 5N/255, from which we get the integer VOLTS= 0.019608*N.

Now, that we’ve got the conversion of raw data to volts, we need to figure out the relevant AFR values. The default analog output of the LC-1 is 0V=7.35 AFR and 5V=22.39 AFR.

http://www.hungryta.com/pictures/WBO2/capture_3.jpg

Since this is a linear output, we can easily calculate the relevant graph equation, which is AFR=3.008V+7.35.

Note: if you have a different wideband controller with different Volts vs AFR relation, you need to calculate the correct linear equation!

Replacing V with the integer above, we get AFR=(3.008*0.0196)*N + 7.35 which equals AFR=0.05896*N + 7.35 ; this function will convert raw data N to AFR.

Now we need to program and display this information into Datamaster, for which we’ll use the Custom Data feature. Click View > Custom Data. On the “Custom Engine Data Display” panel, double click on the first row <Click to Assign>. Fill in the following definitions in the Data Definition table:

http://www.hungryta.com/pictures/WBO2/capture_4.jpg

- Check “Variable Enabled” box, this will enable to display our custom engine data
- Byte Number: 30, this is the byte # in the PCM datastream responsible for A/C pressure raw data “N”
- Information: Air / Fuel Ratio, or anything up to you
- Variable Name: Wideband O2
- Units: AFR
- Gain: 0.05896 ; this is the value from our function above to multiply with raw data “N”
- Offset: 7.35 ; this is the offset value from our function above that is added to the Gain integer
- Data Type: INT ; select this as this value is an integer
- Display Format: 0.00, this will show values of up to 2 decimals

Click OK, you are done!

http://www.hungryta.com/pictures/WBO2/capture_1.jpg

http://www.hungryta.com/pictures/WBO2/capture_2.jpg

You are now able to see WBO2 AFR and RPM at the same time, with all other engine information. Use your favorite dyno tuning spreadsheets to determine new values for the PE tables.

I hope this writeup will benefit for some people and make WBO2 tuning a lot more easier.

If you have some question, please feel free to ask.

Later,
Victor

Nice writeup. I did the same thing. You can't seem to export custom data so I did something very similar in a spreadsheet. In order to get more accuracy and resolution I have a calibration section too. The results from the AFR section are automatically inputed to the tuning section.

If only I had the time to ever work on my web site again I'd put it on the web :(

Nice thread, I've been to Budapest and it was Life changing

Awesome!

Dan

sweet write up man! Keep up the good work..hows the car runing with a new tune? Any more problems with the BLMS?

Guys, I'm glad you liked the info!

Buttercup, why would you want to export the data to a spreadsheet?

JWS6, gimme some info! Have you had the pleasure to try out one (or two) of our world famous ladies lol :D

Marcin, the new tune is fine, although I need some more tweaking with the low pw offset adders, as part throttle is still a biatch.

My question is, will this work on the '93? It sounds like a great way to get the info I need to correct the tuning on my LT1. Thanks for this excellent post!!!

Yes, I see no reason why it wouldn't work on '93s. You'll need the Datamaster DA version (right click save: http://www.ttspowersystems.com/software/dm350/DA/setup-DA.exe)

I don't have bitstream info for '93, but if it's not byte 30 for A/C pressure, then it wouldn't be so difficult to find it either.

My question is, will this work on the '93? It sounds like a great way to get the info I need to correct the tuning on my LT1. Thanks for this excellent post!!!

Great writeup. I went to Budapest a couple of years ago.. that place is amazing:D

This is AWESOME! This should be a sticky.

Sorry to bring back this old post, but I am just getting around to the install.

I've got everything installed and I'm trying to configure Datamaster. I currently have the brown wire from the LC1 connected to the red/black wire from the pressure sensor.

When I open datamaster and go to view, I don't have a "custom data" field. Can this feature only be viewed and changed while connected to a running car? Does it need to be changed every time I intend to scan the car and record the wideband? Will it save the info for the next scan?

The custom data feature is only available in the new version of Datamaster! www.ttspowersystems.com

Damn, I guess I better download the update. Thanks for the great post and the help.

wow thank you!!! I just ordered an LC-1 and ive been looking for this kind of info. definitely should be a sticky!!

This is impressive ingenuity but doesn't a/c activation affect the mapped fuel and spark tables in the pcm. More accurately, won't a false input to this circuit cause a change in the commanded performance? Forgive my ignorance; I am only beginning to look into tuning. I just have the efilive flashscan v1 and innovate LM-1 but have been eyeing the tuning demo.

Is the AC line Pressure connection OBD1 and ODB2 pcms different? I have a 97 (obd2) wiring and converted a ODB1 PCM to work. I taped into the line pressure with the 0-5v output from my WB02 and im not getting any reading in datamaster.

I am about to do this with an LC1, THANKS.

Can you still save and e mail the datalog with this feature enabled? Does it save all of it in the e mail?

David

I can't get this to work either. It appears differently in datamaster for me.

I programmed as listed and "0.058980" results in an output of 7.34-7.36 in my "custom engine data display menu." In your pictures this value field shows as 12.25. The window in datamaster varies between 13.1 and 15.1. It doesn't transistion it just shows either of those two numbers.

Any ideas or possible input? It appears as though the output isn't multiplying by the correct gain.


EDIT *** Never mind I'm an idiot. Make sure your brow output wire is connected. Works great for me.

How did you guys get this to work. I am coming from the brown wire of my LC-1 and I am getting the correct voltage between 0 and 5 with my multimeter. I unplugged the a/c pressure sensor and stuck the wire in the connector spot for the red/blk wire. I reconfigured my data master but i read -15.o or -13.1 like its and open circuit. Do I need to ground out some pins on the connector or something. I have my LC-1 grounded. I am using a 95 PCM in my 97 car, but I read an a/c pressure when its plugged in so it seems like it should be working ok. Any help?

for anyone else as clueless as me.....

The A/f Doesnt display in the a/c pressure spot on the main data screen. It displays in that little custom engine data box that pops up.:o

And make sure your grounds are good

My problem was a bad LC1 controller. I double checked my grounds and it worked great.

The custom data screen is where the corrected data shows up.

Double check the output parameters in the LC1 if you are having problems, mine had changed at one point.

I am having issues with unsteady readings in Datamaster as well. Is there a special trick to grounding the LM-1? I have the 5 volt output and the ground wired to the a/c sensor input. Should the ground wire be grounded to the frame?

The custom data feature is only available in the new version of Datamaster! www.ttspowersystems.com

In Victors Data Definition table where it says "Gain" I see he filled in: 5.898086E-02
I can only fill in numbers and not letters or the - sign.
Anyone know why, or can I just stick with the numbers only??

In Victors Data Definition table where it says "Gain" I see he filled in: 5.898086E-02
I can only fill in numbers and not letters or the - sign.
Anyone know why, or can I just stick with the numbers only??

get rid of the e-02 and just move the decimal place over 2 places to the left

get rid of the e-02 and just move the decimal place over 2 places to the left

akafred, thanks for the info!!
Since I don't have an Innovate LC-1, I'll have to see if I can get my Zeitronix hooked up correctly. Furthermore I don't know if the default analog output of my Zt-2 is 0V=7.35 AFR and 5V=22.39 AFR. I will check with Zeitronix.

Just as an FYI, OBDII allows the same AC-Pressure input, not sure of the pin number, but it's signal wire (not the black or grey one) coming from the low pressure AC line. I use a OBDII scanner that provides AC Pressure in Volts so there's no need to convert the PSI value... just convert it in Excel after uploading the log data.

Also, for those using a DynoJet Wideband commander, the AFR vs voltage formula is:

AFR = 1.6*(Volts) + 10

Obviously if you have a WBC you can already get a log of AFR vs RPM vs TPS vs MAP (or another analog 0-5v input), but piping it into the PCM allows you to get AFR when a DTC sets or along side timing and knock retard data.

Strangely, it seemed that my fans go into "high" when logging (triggered by high AC pressure) even if the AC switch is off. Just something to look for if you're tuning idle quality in OBDII. :)

Do you know of any other sensors that can be used besides AC pressure?

I use the DB guage, so it ties up the brown analog wire.

Can i use the yellow one to tap into the AC sensor instead of the brown?

anybody?

They should both be outputs, so I don't see a problem with that.

Optionally, the YELLOW (Analog out 1) and/or BROWN (Analog out 2) can be connected
to the analog inputs of other devices such as data loggers, ECUs, or gauges. If either one or
both of these wires are not being used isolate and tape the wire(s) out of the way. The default
analog outputs are as follows: Analog output one is 1.1V = 14 AFR and .1V = 15 AFR. This is
a simulated narrowband signal. Analog output two is setup as 0V = 7.35 AFR and 5V = 22.39
AFR.

The guage i use (db), is setup for the brown wire, so the brown wire is tied up, unless i could splice it and run it to the AC wires too?

I am about to do this with an LC1, THANKS.

Can you still save and e mail the datalog with this feature enabled? Does it save all of it in the e mail?

David

Im wondering this too!

I want to log some then send it over to my tuner..

Awesome write-up!

It will log all of the information and save it accordingly. Your tuner will have to program his custom data view with the information provided above to view it. The data is there, but the tuner must input the equation/parameters to view it.

Alright, thanks.

I have some problems tough, when I type in "gain" at 0.05896 it will change itself to 5896, the decimal wont stay. The same with "offset"..?

Ok this is what it looks like when I first put in the values:

http://i235.photobucket.com/albums/ee142/krillformula/frst.jpg


Then I click OK and get ****ed up readings I think, because when I open it up again it looks like this:

http://i235.photobucket.com/albums/ee142/krillformula/sen.jpg

The decimals are all gone in gain and offset :confused:

Any thoughts on how to do the same with a 165 or 730 OBD1 ECM ?

I am using this data to compose a similar setup with my FJO wideband controler and datamaster. I've run into a question when calculating the linear equation. You say that with the LC-1 the equation is AFR=3.008V+7.35.

My question is were did you sumize the 3.008 from? My FJO goes from 10.0 AFR to 20.0 AFR thus I am trying to calculate the new equation. If I know were you came up with the 3.0008 I can complete the equation. If 3.008 holds true in factoring in the correct gain and offset for both controlers I can then use the given equation.

Thanks for your input and GREAT thread!

Edit: Ahh yes my output analog signal will be from 0V to 5V.

Edit: I'm also having trouble figuring out how you derived .0196 from the equation AFR=3.008V+7.35. Could you please explain. THANKS.

that's the slope of the regression line.

Slope = rise/run
Slope = (change in AFR)/(change in voltage) = 10/5 = 2

You can use 2 for your slope and 10 for the intercept (2v+10). The EXACT relationship should be in teh FJO literature or by contacting the company.

the "intercept" is the AFR indicated by 0 volts, the slope will be the gain in AFR per volt (which I estimated around 2 above).

Ok so my equation looks like this: 2V+10. That makes sense. So my offset is 10 but to solve for the correct gain input I need to find out how you derived .0196 from your equation AFR=3.008V+7.35. This is how you came up with your gain.

"Replacing V with the integer above, we get AFR=(3.008*0.0196)*N + 7.35 which equals AFR=0.05896*N + 7.35 ; this function will convert raw data N to AFR."

How do I come up with my ".0196", figuratively speaking, to complete my equation for my final gain input into datamaster. Or are you stating that my gain is in fact right in front of my face: "2"?

what If we still use the AC.. I asume we cant use that wire, Other option?..

I dont use EGR anymore, is there a EGR position sensor I can use?

this was intended for tuning only. when your tuning dont use your ac. when your not tuing plug it back in..

I wired up a simple DPST switch inline with the AC input. One position connects the the AC sensor to the PCM, the other position is the WBO2 input instead.

One note... if you're tuning the idle speed or cyclinder distribution do NOT use the WBO2 (or the AC) as the PCM will adapt for the extra load the aC is seeing... obviously if the AC isn't on this can cause minor rpm fluctuations that affects your idle speed.

Also, if you use a switch like I did, make sure you twist and solder the wires firmly, then paint the contacts with liquid insulation (rubber stuff you can get a Lowe's Hardware or the like) then wrap it in 3M Electrical Tape... keeping the contacts dry will prevent corrosion and help this be a nice long-term installation.


As for the 0.0196 question, that came from the idea of displaying AFR in the AC field in datamaster. I don't use datamaster myself, so I've never had to do it, but that factor is used to "adjust" your voltage to show up in the PSI reading of AC. Take the 2, multiply by 0.0196 and you'll get the actual factor you want to use in datamaster... this way the AC Pressure field will display your AFR directly as a PSI (though the decimal will be 1 off... like XXx.x instead of XX.xx, but that's as close as you'll get by using datamaster).

Excellent! Thank you for your help. Now I don't have to run seperate laptops for each program in the car.

Edit: So for folks using the FJO data input would be same as your's with the following exceptions(be sure that the volts for the Aux output are from 0v to 5v for the calculations to work correctly. Also the min and max AFR set to 10 and 20 respectively) :

Offset = 10
Gain = .0392

I DEFINATLY vote for this to be cleaned up and made a sticky.. GREAT info here that ALOT of people can use!

After you have wired in the wideband controller and it is fully working, hook up the wideband controller analog output signal wire and the analog output ground wire to the relevant A/C pressure sensor connectors. The unused sensor connector can be used for a really clean install.




So I just need to look up which wire on the pressure sensor connector feeds the 5v signal into the PCM and connect that to my 0-5v out on the lc1 correct. Is that the only wire I need to tap into on the pressure sensor?

My LC1 has only 6 wires so I don't have an analog output ground like the LC1's with 7 wires.

If I can get this to work, this will help out my tuning capabilities alot!!!

Thanks everyone, good info!

Has anyone done this successfully with an LM1 yet? I have tried the gain .0392, offset 10 and it didn't match the display AFR.

what i have just done is set the lc1 to output 1.0v at 8.0 afr and 2.5v at 22.1 afr. this way you dont have to use the custom data stuff. all you have to do is move the decimal point over one place. also doing this logs the afr on the bottom graph.

Use your favorite dyno tuning spreadsheets to determine new values for the PE tables.


Does anyone have any of these spreadsheets that they can share?

Does anyone have any of these spreadsheets that they can share?

http://www.noid.org/~lj/PCM%20Tutorial/DynoTune.zip

I use the DB guage, so it ties up the brown analog wire.

Can i use the yellow one to tap into the AC sensor instead of the brown?


Reamo04, Did you ever find and answer to this question? I am also in that boat.
I think we have to reprogram the yellow wire for a 0v-5v reading.

Reamo04, Did you ever find and answer to this question? I am also in that boat.
I think we have to reprogram the yellow wire for a 0v-5v reading.

I put the brown to my guage and the a/c... i wonder if that has anything to dowith my guage reading wrong?

I put the brown to my guage and the a/c... i wonder if that has anything to dowith my guage reading wrong?

It could be. The LC-1 I have has two anolog outputs. The yellow wire is one and the brown wire is the other. These two outputs are set up differently from the factory.
You proly already know that because you spliced from the brown wire to go to two different things.
Anyway I got a CD with my LC-1 that had software on it to program the anologs to whatever you want. You launch the LM Programmer to do this. Since my guage and my AC Switch both take a 0V to 5V anolog output I reprogramed the yellow to that. Worked great!

I would also like to thank Victor for this awsume write up. I wouldn't have had a clue without it. My computer knowledge doesn't go far beyond the key's.LOL

It could be. The LC-1 I have has two anolog outputs. The yellow wire is one and the brown wire is the other. These two outputs are set up differently from the factory.
You proly already know that because you spliced from the brown wire to go to two different things.
Anyway I got a CD with my LC-1 that had software on it to program the anologs to whatever you want. You launch the LM Programmer to do this. Since my guage and my AC Switch both take a 0V to 5V anolog output I reprogramed the yellow to that. Worked great!

I'm not sure i understand... you programmed the wire?

you program the lc-1 using the supplied software. you can set it to output a certian voltage at specific afr..

i use a cheapo 2v 2$ panel mount volt meter in my car. i set the one output to output 0.8v at 8afr and 1.9v at 19afr

then my other output i set for 1.0v at 8.0 afr and 2.5v at 22.1 afr and run that into my ac sensor imput. using these values i didnt have to use and custom data stuff in datamaster and you can graph your afr on the bottom with tps and rpm ect..