Mark P

I had purchased a Zeitronix ZT2 without a display (thanks AutoSpeed) and also an Apexi Turbo Timer, which I had planned to use as my display (since it was much smaller).

Zeitronix ZT2:
<img src="http://www.zeitronix.com/Products/zt2/zt-2kit2-250.jpg"><img src="http://www.zeitronix.com/Products/zt2/zt-2.gif">

Apexi Turbo Timer:
<img src="http://ctny.audiworld.com/mark/s4/turbotimer/dsc05566.jpg">

The ZT2 has a narrowband output and the Apexi has a narrowband input, so it seemed like this would be a great way to get WideBand readings in a small display (and also get turbo timer functionality as well).

I installed the turbo timer and the zeitronix and confirmed all was working as expected.

1.) I did not connect to an RPM signal. Where are people tapping this from?

2.) The Zeitronix has a 0-5V User Input. Has anyone connected this to MAF or MAP or anything else? Does anyone know the curve (linear?) of the stock MAP sensor. It'd be nice just to connect to that instead of buying another boost sensor ($110).

As I was finishing up the install, I finally read all of the instructions and became a little concerned when I saw the Apexi had controls to let you set corresponding points between input Voltage and the corresponding A/F reading. Basically it allows 8 data point pairs, and I assume it does linear interpolation between those points. As such, while it does allow user control, it's not the standard narrowband curve (whatever that actually is, I don't know as I've never been able to find the equation for it).

Here's the points you can set with the Apexi:
<img src="http://ctny.audiworld.com/mark/golf/zeitronix/apexi_tt_af_input_settings.jpg">

The Zeitronix has 3 possible output curves (Narrowband, standard wideband, and linear wideband). Only the narrowband is 0-1V, so that is the only one I can use with the Apexi. If I could have used a 0-5V curve, I would have chosen the linear wideband, as that way I could then set the points in the Apexi to all be linear, which would give the most accurate readings on the display. I suppose I could build some sort of circuit to take the 0-5V and convert it to 0-1V...

Here are the Zeitronix options:
<img src="http://ctny.audiworld.com/mark/golf/zeitronix/zeitronix_output_settings.jpg">

Today, I loaded up the laptop software and compared that display to my turbo timer display. Indeed, the values did not match. I guess I can try tweaking the set points on the Apexi to allow the two to align better. In order to make that easier, it would be nice to have a more detailed function or plot of the narrowband curve. I guess what I really want to know is what voltages the Zeitronix is ouputting for the corresponding A/F that is being measured. I emailed them to (hopefully) get this info, and will then put those data points into my Apexi.

I did find on Zeitronix site that they have a listing of narrowband voltages and corresponding A/F, but this is listed as a reference when reading a narrowband voltage from an OEM sensor in a vehicle. Perhaps their data will be similar and also include values beyond the range they listed here:
<a href="http://www.zeitronix.com/questions/O2questions.htm" target="_blank">http://www.zeitronix.com/questions/O2questions.htm</a>

Here's some previously posted Voltage &amp; A/F &amp; Lambda plots:
<img src="http://ctny.audiworld.com/mark/s4/misc_data/afr_lambda_graph_table.jpg">

<img src="http://www.zeitronix.com/questions/O2transfer.gif">

BTW, all of the above is on my Golf, but it's otherwise relevant. I'm still interested to hear where people are tapping the RPM signal, as I'll likely have to get it from the same location.

iNfiNkC

tach is green/blue at the cluster or at the ecu. sorry i dont have what connector it is. the apex connected to the narrow band output should be set by default to give you a reading, my innovate w/b had a narrowband output and i connected it to an autometer a/f guage and it read fine, its an output like if you were to connect the apex to your stock o2 sensor. I know the normal o2 sensors operate at 0 to 1v and .5 is stoich. its just a linear graph, i think they have a curve to adjust for "your car" real time readings. The apex will never give you an "exact" o2 reading, thats why there is the wideband. if you can get the zetronix display and find a place to mount it so you can a real o2 reading.

Mommasboy

Where did you mount the turbo timer?