Widebands That You Would or Wouldn't Buy

[Fred]

so the ngk afx read 11.2X:1 AFR?

0.8 - 0.03 = 0.77, 0.77 * 14.7 = 11.319. 11.76 would be the correct reading if the gauge displays AFR suitable for gasoline (most likely why you posted such a random thing...).

EDIT: The manual for the AFX (attached for caching) states that it uses an arbitrary stoich value of 14.57, rendering my calculations above wrong. Hentai pointed this out to me. Correct ones are below:

0.8 - 0.03 = 0.77, 0.77 * 14.57 = 11.2189. 11.656 is the correct reading knowing that the gauge displays a stoich AFR of 14.57. Apologies to Hentai for the above comment, which though vague, was useful, but not the below one. Even if Alan used the wrong value for conversion, the device is still in error by a significant amount, IE: 0.776870281400137 instead of 0.8 or an error of 0.023 Lambda rather than 0.03. It'd be nice to clarify anyway.

Get your copy from here rather than the attachment: http://www.ngksparkplugs.com/pdf/AFX_Tu ... REV_06.pdf

This information was gleaned by scoping factory ECUs. ( and the AFX ). I don't think anyone outside of NGK/NTK knows much more than this.

Considering the AFX is not a NGK made item, and is a ECM CO dervied product I would disagree there
http://www.ecm-co.com/

Hentai, read the comment again. Your comment does not make any sense at all. The last one was dubious too. I try not to post in this thread unless I have something to offer as I don't want to dilute what is currently a high signal to noise ratio thread, one of few on any forum. If you could do the same, that'd be great, thanks.

[toalan]

Even the NSA doesn't have good documentation on the NTK sensors.

If you want to try them with your controller.

1. For the original L1H1/L2H2 use an effective constant heater voltage of 10.5v ( relies on heater element PTC )
2. For the later LHA type sensors, target 85ohms on the Nernst cell and control normally. w/ adjusted PID values for higher thermal mass & latency.
3. Bypass the trim resistor. The values are all over the place w/ different applications. Use free-air calibration.
4. Nominal free-air current for the L1H1/L2H2 is ~5.8ma the LHA is about ~3.8ma
5. The heater takes about 20% more power than the Bosch sensors.
6. Pump-current to O2% transfer function is assumed to be linear.
7. Don't apply pump current until temperature stabilized.

This information was gleaned by scoping factory ECUs. ( and the AFX ). I don't think anyone outside of NGK/NTK knows much more than this.

With that, you should be able to get get a good idea of the different performance characteristics, using the same controller. Should be interesting

That is good info, thanks. I will give it a try when I have the time.

I do believe that the NTK sensor is manufactured to much tighter tolerances than the Bosch Sensor, I am inferring this from the calibration resistor which is much higher on the NTK sensors vs the bosch calibration resistor which is much lower. It would explain the higher cost of NTK sensors, with a higher price and tighter tolerances I also expected that the accuracy and response time of the NTK sensor would be superior.

[toalan]

I used 14.7 as the conversion factor, things look a bit better using the 14.57 figure as fred pointed out, though as whole it makes things silly.

[HelmutVonAutobahn]

Accuracy NTK vs. Bosch is a mixed bag.

The NTK sensors are more consistent from unit to unit. That is, the ratio of pump current to o2% between random samples is much closer than with the Bosch sensors. The early L1H1/L2H2 used trim resistor values similar to Bosch ( several values from bins ). The later ones (LHA) have only a few discrete values of trim resistor ( 7.5k 10k 15k 20k 25k ) . So, they are, basically, grouped by lot.

The Bosch sensors have a lot more variation in sensitivity from unit to unit. But, Bosch LASER trims the trim resistors to exactly compensate for the deviation. So, as a complete unit, the Bosch is more accurate. I consistently see free-air currents that are +/- 0.2% of that predicted by the trim resistors. IF THE SENSOR TEMPERATURE IS CORRECT.

Response times is no contest at all. At t90, the Bosch sensors are about 50x faster than the NTK sensors. In lean-to-rich transitions, I have seen the AFX Powerdex trail an LC-1 by over half a second before settling to its final value. Of all of the Bosch-based widebands that I have tested, only the Dynojet unit was nearly that slow.

[TeckniX]

With this being my first post, I wanted to add some info on the Zeitronix wideband.
I've been using the wideband for quite some time, and have found the display to be convenient, since it shows lambda, afr, boost, etc. without having to switch.

I haven't used the device in a while and now can't seem to get any data from it, and the display is showing odd characters, which according to support is due to 'bad wiring' ( I did open the unit to split the 2 pcb and connected them via wires) - I can post picture of that for those that want to see it.

As far as accuracy is concerned, the unit seemed 'accurate' but I don't have the proper lab equipment to verify it. Due to the laptop not connecting to it and the display not working anymore, I'm considering getting the SLC DIY2, which would allow me to keep the wideband currently installed in the car.

On to the controller pictures:





Chips used are:
- MC98SR12
- MAX2321 (41DD25M)
- 3S8 E9344 ?
- ST S34 C306 ?

Anything else let me know.

[toalan]

Does it still work from time to time, or is it pretty much dead?

Would you be interested in doing a swap for a SLC DIY2?

[TeckniX]

Does it still work from time to time, or is it pretty much dead?

Would you be interested in doing a swap for a SLC DIY2?

It should be working, but can't seem to get the zeitronix software to pickup any data from it - There's another local controller for sale I can pick up if you want to do a trade

ps: this is their 2009 version - the 'newer' 2010+ has a little led for activity. The unit can be upgraded by zeitronix for $60 +/- with shipping.

[toalan]

Hi,

Does the LCD work, all I need is to see the AFR/Lambda value when I benchmark it using lab gas.

Does the unit support/require free air calibration? If it does then I assume it is via a PC connection, so I would need the PC connection to work.

[TeckniX]

The LCD does not work, which is what created this update in the first place - I've got an arduino nano coming my way, which will allow me to do some proper testing on the LCD to see if that's the issue or the board translating the serial data to the LCD.

The unit does not require the free air calibration, or at least there is no mention of it in their documentation. It uses the standard Bosch LSU 4.2 sensor. There is a 0-5v analog output for ems/whatever, which may be useful during your lab test.
They use AFR = 2*v+9.6

http://www.zeitronix.com/installation/Z ... ctions.pdf

[HelmutVonAutobahn]

Do they document their serial data format ?