running_cold924

i have an aem wideband and am trying to figure out which line the smt6 needs. the aem has 2 choices, use the 0-5V output or a serial output line. what does the smt6 need to see?

Scott H

0-5v is the WB standard, a serial output is usually for data logging.

running_cold924

well after going through a couple old posts, looks like people have put it in the engine temp category to use the 0-5V reference.

Tom M'Guinn

It's nice to have the temp connected to the temp sensor for warm up tuning purposes. So, I made a voltage divider using 1k and 4K precision resistors to convert the 0-5 output to a 0-1 volt signal, and then connected that to the narrow band input of the SMT6. With my zeitronix, it works remarkably well. I have to convert the output in my head (e.g., .22 volts equals exactly 11.8:1 with the zeitronix output) or log it and convert if via Excel, but it is spot on accurate. You just need to know the 0-5 output scale on your wideband so you can interpret the voltages. Here is Xeitronix's schematic for doing this:

http://www.zeitronix.com/Products/Zt...nt_setup.shtml

Dea_944t

If you have a Zeitronix can't you use the simulated narrowband output to the 02 input on the SMT-6?
If I understood correctly that output should be pretty correct as it's simulated from the wideband signal?

I connected it that way but I'm not using it since I'm only logging with the Zeitronix.

/Dea

Tom M'Guinn

I tried that, but was surprised to find that it only simulates the switch point -- i.e., it was essentially a binary output that would toggle between rich and lean based on whatever set point AFR you set in the zeitronix. I assume that's why they posted a schematic showing how to convert the 0-5v linear output to a 0-1v scale... Other wideband systems may have a true linear 0-1v output, but I've only used the zeit really.

Dea_944t

OK, good info! another cable connection that can be removed.... (don't think the SMT-6 uses the 02 input for anything, just logs it?)

What's the reason you've chosen to log with the SMT-6?

/Dea

Tom M'Guinn

I wanted to have a single log that showed exactly what AFR I was getting while in each cell of the SMT6, so I could know exactly which cells to adjust to get my intended AFRs at any given point. Otherwise, there is a bit of trial and error getting the AFR curve exactly where I wanted it, as you have to look at the AFR curve in the zeitronix and then try to pick the right cell's to adjust in the SMT6. It can be done, but having it together makes it very easy -- since you can just review the log and see exactly which cells are resulting in a leaner or richer AFR than you'd like.

The SMT6 also logs more signals (temp, MAF in and out, etc.)

Dea_944t

That does sound pretty useful, I should probably read the SMT-6 manual a bit closer....

/Dea

fast951

Dea, I believe you have the newest PB Gray box. The software is different than what Tom has.

With the new unit, there is a cursor tracer function that highlights the cell in use making cell identification much simpler.

Tom M'Guinn

I have the tracer function -- thats why its so nice to have the piggyback log real afr's. You can step through the log and look at the actual afr you are getting on a cell by cell basis. Its just a nice convenience i think...

fast951

I stand corrected For some reason I was thinking you have the older unit...

Dea_944t

Since it's just to solder two resistors it's a 10min fix and definitely worth doing.
What temp are you logging with the SMT-6, engine temp?

/Dea

Tom M'Guinn

I 'think' i have it. The active cell is highlighted in red and if i set the tracer it highlights all the cells it moved through in orange, so you can see its path. That's it, yes?

running_cold924

cool, good info Tom, thanks!