NAW always shows around 14.7

[rvanwin]

I purchased a NAW unit a couple of months ago with a new Bosch Sensor and am now installing the unit.  When I first started up after installing, the display read 14.7 +/- .2 or so.  I expected it to show rich during warm-up but thought maybe that was the actual AFR.  However, when I went for a test drive, it stayed around 14.7 regardless of whether I was in Power Enrichment (PE) or in Lean Cruise (commanded AFR of 16.6). Also, checked the display on my ECU which accepts and displays 0v - 5v Wideband output with essentially the same 14.7 numbers.  My narrowband shows pegged at rich when in PE and pegged at lean when in Lean Cruise.  Even when I turned the engine off and with the key on, the display shows 14.7 +/- .2.  So, this is what I have done:

1) Swapped the new Bosch Sensor with another sensor with same results.
2) Checked lights.  Start with green lit when cold, goes to red, then settles down to yellow.
3) Checked all wires - to make sure they were connected to correct pinouts - all were validated.
4) Checked voltages on screw pinouts with following results:
    pin 1  = 13.6 volts when grounded to pin 2
    pin 3  = 13.6 volts when grounded to pin 4
    pin 5 = 13.6 volts when grounded to pin 6
    pin 7 = 2.08 +/- .1 steady under all throttle conditions
    pin 8 = 2.5 +/- .1 steady under all throttle conditions
    pin 9 = 1.5 - 2.3 with or without throttle change
    pin 10 = 1.5 = 2.4 with throttle change - would consistently go to 2.4 when ECU commanded Lean Cruise other wise at around 1.5 even when in PE.
    pin 12 going to ECU = 2.4 +/- .2  with no change with throttle change.

The result is that I have a WB that always shows being at 14.7.  Any ideas or anything else I can check?

Thanks,
Randy

[admin]

Hi,

Connect the unit to PC, in the real time display there is a "Ip Gauge" tell me what value the IP gauge shows when the sensor is in free air and @ ~750 degrees.

REgards,

Alan to

[rvanwin]

Thank you for your response.

Not sure what you mean by 750 degrees?  On the RT-Form, the temp gauge shows 0 to 200 with the sensor in free- air.  With key on it shows 100 (yellow).

The Lp gauge shows consistently zero ( plus or minus 0.2).  AFR is showing 14.7 with minor fluctuations.

Thanks,

Randy

[admin]

my bad, I was thinking about the temperature gauge for SLC, NAW will show 100 when at proper temperature.

14.7 is consistent with an IP of close to 0, so the issue is not a software settings problem.

when the sensor is in free air and at proper temperature can you measure the voltage difference between Pin 9 and pin 10, the voltage difference should be ~0.15v. My guess is that on your unit the voltage difference is close to 0, which probably means that there is an issue with the wiring on pin 10, pin10 is physically disconnected from the sensor somehow.

Regards,

Alan to

[rvanwin]

I checked the pinouts on the NAW blocks.  They are hard to get wires into.  It appeared that perhaps the pin 10 wire may not have seated properly under the screw.  After redoing that, the NAW seems to be working more as expected.  However, I'm concerned that it displays everything as way too rich.  My NB is getting crosscounts like crazy which should be keeping AFR at around 14.7.  The WB is displaying a full point down bouncing either side of around 13.7.   This gives concern about the accuracy of the NAW.  I read about Free Air Calibration but you say in a sticky not to use it but to set it to zero.  I don't see any way to set it to set it to zero.  On the RT screen there is a "Trigger for FAC" but it is greyed out and has no affect when I click on it.   Am I missing something about how to set this up?  At present, I have no confidence in what I'm seeing on the display but short of installing a different WB controller, I have no way to validate its accuracy?

Randy

[admin]

If you want high accuracy for lambda>1 (lean) then free air is an ok calibration gas, for high accuracy for lambda <1 (rich) then you need rich calibration gas. Bosch calibrates the sensor from factory with rich gas, so it is very accurate for rich measurement. I do not support free air calibration because it destroys the rich accuracy of the sensor while increasing the lean accuracy.

Each NAW_7s unit is 0.01 lambda accurate, each unit gets calibrated before I ship. I stand behind the product. The only way to 100% confirm the accuracy is to use rich calibration gas.

In free air, what is the Ip gauge showing?

does both the physical display unit and the software show the same AFR?

[rvanwin]

Thanks for your patience while I try to understand how all this works.  I removed the sensor and left in Free Air.  The gauge went lean with the physical display tracking the RT Form until 99.99.  I then put a rag soaked in Brake Cleaner over the sensor and the gauge went full rich and stayed there until the rag dried.  The pdf at http://www.pggp.com/GMC/14point7_rvanwin.pdf shows the RT gauge with sensor in free air (1st image) the Edit screen for reference, and the 3rd image is when the sensor was full rich.  I repeated the same process with a second sensor with almost identical results.

I was wondering about the Reset Calibration Value button. When I was first trying to get this stuff to work, I clicked that button a couple of times (the sensor was not functioning properly then because of pin 10).  How does this button work and what affect might it have on the unit?  Also, your comments in the sticky about Free Air Calibration says to set the free air calibration to zero.  How is that accomplished?  Does clicking on the Reset NAW_7S Memory reset the calibration to zero?  Sorry for so many questions but I am finding very little information on how all of this works.

Thank for all of your help, Randy

[admin]

When hit the reset calbration value, it sets it to 0. Once it is set to 0, it will still stay at 0 until you do a free air calibration.

Is the sensor new? the free air IP value is a bit low.

REgards,

Alan To

[rvanwin]

Thanks for the quick response.  Yes, I assume the sensor is new as that is the one I purchase from you along with the NAW_7S and this is the first install.  I also tested a second sensor which is close to new (used very little) and it has almost the same IP value.

If for whatever reason the lP is low would that cause the AFR to read low?

Randy

[admin]

Ip for free air can be anywhere from 70-80 for a new sensor, usually it is closer to 75. 

Everything checks out on your unit, I have confidence that the unit is reading correctly. Double check your wiring and make sure everything is well connected.

[rvanwin]

Still trying to build confidence.  I have a friend with basically the same engine setup as mine.  He uses a LC1 and shows AFR averaging around 14.5 when NB crosscounts are going like crazy.  Still a little lower than 14.7 but plausible.  I put my vehicle close to his and plugged my setup into his exhaust.  We then monitored under the same conditions running same RPM and with the crosscounts on the NB being similar to the earlier run with the LC1.  The NAW shows close to the same as I have been seeing on my engine, averaging around 13.8.

So not to belabor this issue, I believe I'm sampling exhaust that should be close to 14.7 and yet I continue to see values on the NAW at about 1 full unit below 14.7.  I'm open to other ways to validate the NAW.  I don't believe NBs are generally inaccurate plus we have now tested on two different engines. 

Randy

[admin]

the stoich point is the most accurate point on the sensor, it is also the most accurate point on the controller. The signals from the sensor at 14.7 AFR are very obvious and leave very little room for the controller to make an error.  I just can not see how the sensor or controller is having a problem with stoich.