[Diy_efi] wide band O2's
WopOnTour
wopontour
Wed Jul 6 14:45:52 UTC 2005
MessageThanks Gary
That makes sense, certainly the oems need to consider the negative consumer effects of requiring a routine calibration. In this day-and-age of maximizing service intervals that wouldn't make sense. I guess I was leaning towards the controllers/sensors ability to maintain sufficient accuracy for a complete "life cycle" (typically 160,000km for standard zirconium sensors) Sufficient I guess for complying with FTP, but not necessarily with the high accuracy demands of a competition tune.
However a "free-air" calibration process only confirms the accuracy of the sensor under lean conditions only (@20% concentration-partial pressure) If these must be performed routinely, under the severe use of a performance application, wouldn't it then make sense that the sensor also be tested for "rich-end" or even stoich accuracy using various BAR certified blends? This to calibrate for the sensor skew you describe that should affect the sensor ability to react to HC, H2 and CO to establish an accurate rich AFR. So my question is (in a nut shell) if one check and recalibration is so important (lean/free-air), why not the other side of the AFR equation??
Regards
WopOnTour
----- Original Message -----
From: gary
To: diy_efi at diy-efi.org
Sent: Wednesday, July 06, 2005 7:57 AM
Subject: Re: [Diy_efi] wide band O2's
> One thing I noticed is that the oe solutions from Bosch NEVER
> describe any sort of routine calibration, as most of the current
> aftermarket solutions claim was necessary. So it is my desire to
> determine (if I can) HOW the oem WB02 hardware and/or control
> strategies are so different that they do not require any sort of "zero
> oxygen" calibration apparently for the life of the vehicle (or the life
> of the sensor- which ever comes first! LOL
> It's been known that these ASICS do not require routine calibration
> as they derive a trim solution based on the sensor calibration resistance.
> I'm curious what the source/root cause of any significant drift might
> be - normal chemical breakdown? contamination?
The ALL analog circuitry was designed for OEM applications. The
OEM WB sensor is not subjected to the abuse it endures in a
'performance' or 'tuning' tupe application, be it lead, or something
less severe like AFRs on the rich side of stoich, (IOW 12.0 AFR
or even richer) something not experienced by a sensor in an OEM
application. This unusual wear 'n' tear causes the WB sensors to
drift. Without the abuse that causes this drift, there is/was no need
for manual calibrating/compensating circuitry in the OEM analog
circuitry. HTH.
GAS
----- Original Message -----
From: "WopOnTour" <wopontour at hotmail.com>
To: <diy_efi at diy-efi.org>
Sent: Wednesday, July 06, 2005 12:09 AM
Subject: Re: [Diy_efi] wide band O2's
> Well to clarify my own intentions/motives
> I have been searching for an aftermarket or DIY WBO2 controller
> solution based on either the CJ120 or CJ125 for many months. It is
> apparent that Bosch is using these in their existing engine management
> systems, but I have yet to find a stand-alone unit or even schematics
> to construct a complete controller (other than what's provided in the
> Bosch datasheets) No I was told (from a usually reliable resource)
> that the PLX controller was using these ICs. (and it just, by shear
> coincidence, coincided with WBO2 discussions on this list)
> Does anyone know of any WB02 controllers that are actually based
> on the genuine Bosch ICs designed to maximize their performance??
>
> *Currently I am working with what I call my "wrecking yard" WBO2
> solution, scamming a Bosch Motronic ME3.1 controller off a wrecked
> 2003 Saturn VUE (with that same GME V6 discussed earlier) and
> am using an oem scan tool to observe the WBO2 PIDs via the K-line
> datastream. One thing I noticed is that the oe solutions from Bosch
> NEVER describe any sort of routine calibration, as most of the current
> aftermarket solutions claim was necessary. So it is my desire to determine
> (if I can) HOW the oem WB02 hardware and/or control strategies are
> so different that they do not require any sort of "zero oxygen" calibration
> apparently for the life of the vehicle (or the life of the sensor- which ever
> comes first! LOL
----- Original Message -----
From: WopOnTour
To: diy_efi at diy-efi.org
Sent: Tuesday, July 05, 2005 11:31 PM
Subject: Re: [Diy_efi] wide band O2's
Thanks gary
I think I understand your concern (and don't disagree)
But as the controller is maintaining pumping cell and heater current in a
closed loop fashion, wouldn't this allow for drift or skew that occurs over
time? I'm curious what the source/root cause of any significant drift might
be - normal chemical breakdown? contamination?
Thanks for sharing your thoughts
Regards
WOT
----- Original Message -----
From: gary
To: diy_efi at diy-efi.org
Sent: Tuesday, July 05, 2005 9:38 PM
Subject: Re: [Diy_efi] wide band O2's
As I understand it, WB controller (analog) circuitry that relies on
a sensor calibration resistor without manual calibration, does not
allow for sensor outputs as they drift over time/use. The sensors
drift, but the calibration resistor stays the same. I question the
accuracy over time/use.
GAS
----- Original Message -----
From: WopOnTour
To: diy_efi at diy-efi.org
Sent: Tuesday, July 05, 2005 10:08 PM
Subject: Re: [Diy_efi] wide band O2's
Wouldn't it depend on what ASIC was chosen to provide nurnst and
pumping cell current control and AC-DC measurement?... It's been
known that these ASICS do not require routine calibration as they
derive a trim solution based on the sensor calibration resistance.
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