Help me understand O2 sensor options

K-Series Programmable ECU installation questions / support issues
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alexx19
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Help me understand O2 sensor options

Post by alexx19 » Sun Dec 24, 2006 11:37 am

Can you tell me what's unique about the 02-04 RSX primary O2 sensor?

More specifically, what voltage/current is the ECU expecting?

(I'd also be curious to know what's different in the 05-06 RSX vs. the O2 sensor vs. the 02-04 RSX.)

I'm building a full race motor and will only have a primary oxygen sensor and will probably run leaded fuel which kills my O2 sensors about every 4 months. In my last motor I used the wideband O2 sensors from a VW and was getting those for $38 - yes they are wideband Bosch LSU units - see http://wbo2.com/lsu/default.htm for more information. I ran this with the Innovative LC-1 controller.

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It seems to me that less expensive O2 sensors must be an option.

Here's are some LSU wideband O2 sensors (I used to pay $38 for the VW one but I think they are still less than $50):

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They come in many cars with many types of lengths and ends. See http://wbo2.com/lsu/sensors.htm for some part #s and more info.

(I used this on my last engine build along with a custom FI system and controlled with a MegaSquirt ECU.)

Maybe you could use a controller along with a less expensive O2 sensor?

The LC-1 Wideband Controller by Innovative Motorsports is programmable so you could output any voltage necessary to be compatible with the ECU. Here's the stock table but it is programmable: (from http://www.innovatemotorsports.com/products/lc1.php)

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You just program 2 points on the line and the controller does the rest.

Maybe you wouldn't need to buy another controller and could hook up an LSU (Pump type wideband O2) directly to the ECU? But the controller and sensor is less than the price of just the RSX O2 sensor.

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I assume that the ECU (PRB, PRC, etc.) has a wideband controller included so maybe it has some kind of funky interface to the ECU. Maybe this could be jumped and/or disconnected so that another controller can plug in its output after that? (Just a thought while I think outside the box.)


PS Here's a link to the Bosch technical documentation on this sensor: http://wbo2.com/lsu/Y258K01005e03mar21eng.pdf

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Hondata
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Post by Hondata » Tue Dec 26, 2006 12:14 pm

Narrow band o2 sensors work by the difference in oxygen levels between the exhaust gas and outside air creating a voltage difference across a ZrO2 Nernst cell. They don't require any power to produce an output, and the ECU can just read the voltage from the narrow band sensor.

Wideband o2 sensors add an oxygen pump cell and reference cell with heater to the Nernst cell. A controller regulates the current through the oxygen pump cell and also the heater current. The ECU cannot read a wideband sensor and there must use a wideband controller to run the o2 sensor. The wideband o2 sensor does not produce a voltage, but rather the amount of current through the oxygen cell tells us the AF ratio. The amount of current varies by o2 sensor but some are as low as +- 1mA full scale.

The difficulty is that the wideband controller must be matched to the o2 sensor. The reason is that the amount of cell current and heater current is critical for the life of the o2 sensor. Cold start current regulation is very important and it actually is possible to destroy an o2 sensor in a single cold start. This is why we do not recommend that people wire in anything at all to the o2 sensor wiring. An external AF meter will not read the wideband o2 correctly, and more than likely will consume enough current to throw off the reading drastically. Swapping o2 sensors is equally as hazardous.

To replace the RSX o2 you will need to find an exact equivalent o2 sensor, as the wideband controller electronics is integral with the ECU and cannot be replaced nor altered. The other options would be to run a cheap narrowband o2 sensor, and use the secondary o2 sensor input for closed loop (which you will be able to do for the next KManager release), or to use an external wideband controller which uses a cheaper wideband sensor and feed the analog output from it into the secondary o2 sensor input as above.
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03DSM-RSX
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Post by 03DSM-RSX » Fri Dec 29, 2006 12:17 am

wow i cant wait for that new revision!! :D

to clarify, you're saying is that i can either:

-use the output wire of my AEM UEGO wideband gauge/controller, and wire it to the secondary o2 input wire (whereever that is...) and kpro will run closed loop according to those readouts

-use a generic "cheap" narrowband (any kind in particular??) plug it up into the secondary o2 plug, and have kpro run closed loop according to that

correct?

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Post by Hondata » Wed Jan 03, 2007 10:33 am

Yes, and yes. The only issue is that you'll need to run a PRA calibration.
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Mr Aryan
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Post by Mr Aryan » Fri Jan 05, 2007 5:59 am

03DSM-RSX wrote: -use the output wire of my AEM UEGO wideband gauge/controller, and wire it to the secondary o2 input wire (whereever that is...) and kpro will run closed loop according to those readouts
and what changes should be done to the setup after you wire the UEGO?

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