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Old 08-11-2008, 10:31 PM   #1
beb
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(VX/HX) 5-wire O2 Sensor Rcal values?

With all of the issues and/or expense involved in finding a replacement L1H1 or L2H2 O2 sensor, I'm tyring to figure out a circuit that would allow the use of a Bosch LSU 4.2 O2 sensor (which is cheap and abundant) while providing a P07 ECU with an interface consistent with the signals that would come out of and go to a L1H1/L2H2.

One of the issues in getting this to work is figuring out how Rcal is used (Rcal is the calibration resistor packaged in the connector; it tells the ECU a correction factor to use particular to that specific O2 sensor). I haven't gotten around to it yet, but am hoping that I can reverse engineer the basic circuit it's in by opening up my ECU.

Even with the ECU open and traced out, one thing that I don't have is even one L1H1/L2H2 O2 sensor to examine (it was pulled off of my scavanged D15Z1), so I don't have any idea what sort of values Rcal could even have (FWIW, I'll pay shipping to anyone willing to send me their trash L1H1 or L2H2).

Has anybody measured theirs? It is wired directly to pins 3 and 4 of the 8-pin connector's sensor side; on a VX, the harness side should have a white wire going to pin 4 and a grn/wht wire going to pin 3. Just placing the probes of an Ohmmeter to these two of the sensor's pins (while the plug is disconnected!) will directly read Rcal's value.

With so many questionable and arguably counterfeit L1H1/L2H2 sensors on the secondary market, it is also going to be necessary to catagorize Rcal values by source (which might produce the info that reveals just how they're being counterfeited).


So I'm asking for two things from those kind enough to contribute:
1) What is the value of your L1H1/L2H2's Rcal?
2) What is the source of your O2 sensor (e.g., unknown, Honda, Bosch, Quality Parts on eBay, evalero on eBay, etc.)?

Thanks
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Old 09-07-2008, 11:57 AM   #2
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Bump this thread, I am hoping beb is onto something that could be a huge help to many of us.
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Old 09-08-2008, 09:39 AM   #3
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Quote:
Originally Posted by beb View Post
So I'm asking for two things from those kind enough to contribute:
1) What is the value of your L1H1/L2H2's Rcal?
2) What is the source of your O2 sensor (e.g., unknown, Honda, Bosch, Quality Parts on eBay, evalero on eBay, etc.)?

Thanks
1) I have a rough value of 4K Ohms on one L1H1 and a value of 6K Ohms on another L1H1 (will get exacts later)

2) Both sensors were Bosch units purchased in 2000

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Old 11-13-2008, 09:20 PM   #4
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I'm sorry, I don't always know how to read what my meter is telling me, but I know I measured the resistence of the resister in place on the plug. I don't know how to report the values so I'll list it serveral ways at let someone who is not a rank amatuer correct me:

New Bosch five wire with oem numbers printed on it purchased on eBay, throws CEL 48 (o2 sensor) returned for full refund:
0.029 Sperry DM-5300 meter set to 2M
29.8 Sperry DM-5300 meter set to 200k

Existing Honda OEM after 7 years and 100,000 miles, no CEL:
.004 Sperry DM-5300 meter set to 2M
4.2 Sperry DM-5300 meter set to 200k

Seems to me that they are not at all similar.

Pix of the Bosch that throws code:

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Old 11-14-2008, 07:54 AM   #5
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^^^yah, it looks like the Bosch one is way high on resistance. If the plug design is the same (which is should be) you can swap out the resistors between the units to see if the Bosch one will stop throwing the code. you just use needle nose pliers and pull straight out on the white insert in the O2 plug and the resistor comes with it. It looks like a black micro fuse.
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controversy is an idea thought up by weak people who are too afraid to hear the truth.
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Old 11-14-2008, 09:39 AM   #6
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Here is a side by side of the plug of the above respective sensors. Bosch on the left, Honda eom on right. You're saying that you can successfully get at the oem resistor that appears encased?

Also, my oem o2 sensor is not throwing CEL so I'd rather not cannibalize until then. It must be nearing the end of its useful life @ 101,000 miles on it so I've begun a search for a replacment. The Bosch unit is the first failed attempt, quest will continue...
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Old 11-14-2008, 10:43 AM   #7
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I can't see the pictures from work but will check this evening. but yes, it's very easy to remove the resistor by removing the white insert resting inside the connector, the resistor comes out with that.
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Old 11-14-2008, 04:09 PM   #8
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I have read extensively about wide band sensors in the past year. The calibration resistor's ohm rating is unique to each sensor. That's why they call it Rcal.

The manufacturing variation problem, which results in sensors of varying sensitivities (differing pump currents or the same Lambda), is solved by adding a calibration component. A resistor (Rcal) is laser trimmed after the sensor is constructed and tested. The laser burns away material and increases the value of the resistor until a standard Ip current is produced at a known Lambda value.

Each sensor is factory calibrated, and the calibration component is usually in the sensor connector itself, if someone removes the connector, then the sensor has become uncalibrated.
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Old 11-14-2008, 05:25 PM   #9
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Quote:
Originally Posted by SCoupe View Post
Existing Honda OEM after 7 years and 100,000 miles, no CEL:
.004 Sperry DM-5300 meter set to 2M
4.2 Sperry DM-5300 meter set to 200k[/B]
The setting on the meter is the range it will read... The maximum value it will read out. There's only so many digits on the meter, so the higher range, the less precise it will be. The letter at the end is a typical SI-unit multiplier: M = mega = 1,000,000 K = kilo = 1,000. So, setting the range to 2 mega-ohms means the meter will read out in millions of ohms. 0.004 mega-ohms is 4 kilo-ohms, or 4,000 ohms. The lower 200K range gave you a more precise reading: 4.2 kilo-ohms - 4,200 ohms.
If your meter has a 20K range, it will give you a still more precise reading.

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Here is a side by side of the plug of the above respective sensors. Bosch on the left, Honda eom on right. You're saying that you can successfully get at the oem resistor that appears encased?
No need... Just swap the whole connector casing with the resistor inside. I only have a 4-pin connector to demonstrate, but the construction should be the same. If you look into the OEM connector, there should be a white plastic insert:

Pull the insert out with a pair of needle-nose pliers. Once it's out of the way, you should see just the grey connector and the pins. Each pin is held in place by a catch and a spring-tab:

Push a pin off of it's catch (against the spring-tab) and pull it out of the connector from the wire-side:


To reinstall a pin, just orient it in the right direction and slide it into the connector. It should click into place. Once all the pins are installed, slide the insert back into place. It should also click in.
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Old 11-14-2008, 08:19 PM   #10
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Here is what the Resistor looks like:


The "M26" marking is proprietary to the manufacturer, but I can say this:
The "M26" measures 6.18KOhms.
The "K11" one I have reads 4.11KOhms.

I had built an extension for my LAF due to having an aftermarket header. I hadn't swapped the Rcals between the two O2s and discovered having the M26 in with the new O2 made for some bad driveability. I swapped out to the K11 at the point where my extension connects to the engine harness and driveability was restored.

The picture of the Aftermarket LAF is showing me that it is using a standard non-laser cut resistor. Since I can't see the color bands on it I'm not able to tell you if it's a 20%, 10%, or 1% resistor...meaning that is the tolerance of what resistance it gives. So if that is a 30KOhm resistor in the Bosch unit it can read 20%, 10%, or 1% high/low and be withing the spec of the manufacturer. Unfortunately, that 29.8KOhm it reads is about 23-25KOhms higher than any Rcal resistance that I've measured. This could be what is causing the CEL to light with the Bosch unit.

What you can do is go to an electronics parts store or even Radio Shack and get resistors in the range of 4-6KOhms or even a 10KOhm potentiometer. Then you could remove the resistor from the Bosch unit and try different resistors/settings on the potentiometer until you get satisfactory driveability and no CEL.

-or-

On the OEM LAF you can pull out the white insert with the Rcal and put it back in without damaging the connector or un-calibrating the LAF. so you can do what Bobski said without worry. There maybe a slight learning curve on getting the wires to de-pin, but they are resilient and can take some abuse.

The resistor has no direct effect on the LAF, it is merely a factor that the ECU looks at in order to be able to effectively interpret the LAF signal.

I hope this clears some things up for you.
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