Bob_760

Anyone know what values to use to use a Defi A/F Gauge to read from the linear output from a wideband?
I have it kinda working but it obvously needs more adjustment, i was wondering if anyone had solid numbers to use for this instead of me having to "tune" it.
Thanks,
-Kurt

-For referance i am using an Innovate LC-1 with a Defi D-Gauge A/F

rynberg

It won't work. The Defi gauge is expecting a 0-1V narrowband signal, not a 0-5V wideband signal. Unless the simulated narrowband output on the LM-1 actually has a linear voltage to AFR (which would be surprising), the Defi gauge won't react any more accurately than one hooked to the stock o2 sensor.

Bob_760

Thats exactly what it has, it can be as linear or non linear as u want, you input a range of voltage and a range of AFR/Lamda value and it shows the graph and everything, i just need to know what the Defi A/F Gauge is looking for.

rynberg

Here's the procedure: http://www.innovatemotorsports.com/s...ual/Analog.pdf

Unless you get specs from Defi (shoot them an email), you'll have to calibrate your response curve using another readout from the LM-1 (wideband output to laptop, for example). Shouldn't be too difficult.

cooljerk187

you might want to try the PLX wideband-narrowband guage converter. it is only 30 bucks, and id assume it works on widebands other than PLX, as all widebands send the 0-5v reading

Hyperite

That's what I have...piece of ****.

Hyperite

Hmm...I have the Defi specs, I wonder if I can do something similar with the AEM computer.

Bob_760

The Innovate wideband has fully adjustable output so i can mimic what that box does, but i can also adjust it, i was hoping someone would have the values allready figured out since both Defis and Wideband seem pretty common around here =P

Defi specs?!
If you mean the graph in the Defi instruction book I looked at that but its kinda vauge, mostly im not sure how to make it accurate over a wider range using a curve like that. Care to elaborate?

AgentSpeed

I used the cover off my Defi O2 gauge when I trashed it. Now at least the XD-1 gauge kinda matches...

maxcooper

It should be possible to use a 1.5v battery, a variable resistor (potentiometer), and a voltmeter/ohmmeter to test the gauge and come up with your own voltage-versus-AFreading table. Measure the resistance of the gauge and use Ohm's law (V=I*R) and series resistance (Rtotal = Rgauge + Rpotentiometer) rules to choose a variable resistor. Keep in mind that the current (I) will be the same anywhere in the circuit, and you can apply Ohm's law to calc the voltage that the gauge will see. You'll also have to figure out what range of voltages you want to test (what voltage is stoich for a narrow-band O2 sensor?).

This is pretty easy, and it might even be fun if you want to gain a little electronics knowledge. If you want to try it, measure the resistance of the gauge, post the reading, and I'll help walk you through the rest of it.

-Max

Bob_760

Yeah this is exactly what i was going to do today but i bought the wrong potentiometer... it was in the wrong spot...
Just checking if anyone had done this and had numbers before i go get another pot and try again.
I hadent thought about testing the resistance of the gauge itself and all that, I was just going to see at what voltages what AFRs it reads and try to make the Innovate's analog output graph match it. We'll see what happens tomarrow.
Thanks,
-Kurt

cmartinp28

plx has an analog output for their widebnd kits.... and you dont have to do inensive wiring either.

maxcooper

Measuring the resistance of the gauge will aid in selecting an appropriate pot. For instance, if the pot is equal to the resistance of the gauge, you'll only be able to get the gauge voltage down to half of the supply (e.g. 0.75v if you are using a 1.5v battery).

In addition to the pot, you could wire in a fixed resistor that is half of the gauge resistance -- that will give about 1.0v to the gauge when the pot is adjusted down to 0 ohms. And will give you a little finer adjustment with the pot's range of adjustment.

For instance, if the gauge is 10K ohms and you have a 5K ohm fixed resistor and a 15K pot wired in series with a 1.5v battery, you will be able to use the pot to adjust the voltage between about 0.5v and 1.0v.

NiCd and NiMH batteries (well, cells) have slightly voltage (1.25v or 1.2v) if you end up wanting to measure a little lower voltages than you get with a 1.5v battery.

Be sure to measure the voltage across the gauge with a meter while testing to get the actual voltage it is seeing.

-Max

klatinn

Hi,

As I understand, the DEFI gauge is designed to hook up to a NBO2 sensor. In order to not interfere with the operation of that sensor, it has to have an input impedance of at least 200 kOhm. Otherwise it would load the sensor too much. Because of that you can use any pot with less than 20 kOhm.
Those have 3 terminals. Connect one outer one to the + side of a 1.5V battery, the other outer terminal to ground AND also ground the - side of the 1.5V battery.
Connect the center terminal to the gauge and to a multimeter (other side of multimeter to ground.
Then vary the pot and read both the voltages and the gauge. Use the min and max readings to program the LC-1.

Regards,
Klaus

poss

iTrader: (5)

I've been wanting to do this for awhile but haven't got around to buying the gauge.

WaachBack

iTrader: (21)

Would anyone be able to give me some info on this? I have already wired my gauge in and would hate to take it out to measure the resistance. If anyone knows, I need the Defi gauge resistance, what pot to use, and what values to enter into the Datalogit. Thanks