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LSU4.9 Sensor Simulator 
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LQFP112 - Up with the play

Joined: Mon Jun 21, 2010 4:18 pm
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I need to develop a circuit that will simulate a Bosch LSU4.9 wideband sensor.
It will used for basic "check for brains" testing of a wideband controller in a production environment.

I thought that I would ask if anyone had any suggestions (Toalan, Hot Fire, ...) before I start getting heavily into this project.
Any help would be appreciated.

Thanks,
Tony S.


Wed Oct 23, 2013 1:32 pm
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Wideband Wizard

Joined: Tue Jun 10, 2008 2:53 am
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Location: Toronto Canada
I would not make a real simulator, if you are using a Bosch IC for lambda control then I would just use a real 4.9 sensor, it only takes 30 seconds to 1 minute for the sensor to heat up to read free air. I have never worked with the Bosch IC so I do not know what kind of output is expected from the IC in free air but it should have a reading in free air.

If you are building a controller from scratch then you have a reasonable probability that there are several sources of errors either from assembly/soldering problems or with bad components, I would devise a series of tests for each specific circuit/functional block and once the unit passes individual tests then run the unit with a real sensor at the end and measure what the pump current is either in free air or with test gas. For instance in some of my designs the amplifier stage tends to have the highest probability of problems WRT other parts, so I have a specific test on the amplifier stage where I feed in a precise voltage and measure the output via an ADC, I calculate the offset and linear error of the amplifier stage, if the difference between the calculated and the theoretical value is too large then the unit fails, if it passes then the calculated values are stored in firmware and used to trim the ADC readings. If the controller is built from scratch then the designer should be the one devising the quality control tests and integrating them into the firmware/hardware.

Quality control is a real pain in the butt for a production environment, if you want to build a great sensor simulator then it could very well be more work than building a controller from scratch, my quality control and calibration firmware for some of my products is actually larger than the normal firmware that controls the lambda sensor.

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Sat Oct 26, 2013 2:51 am
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LQFP112 - Up with the play

Joined: Mon Jun 21, 2010 4:18 pm
Posts: 192
Thanks Alan.

Basically what I am looking for is a circuit that would satisfy the basic requirements of the wideband controller enough that the controller would report a fairly stable A/F ratio of any reasonable value without sensing a fault.

I did do some more "Google"-ing and realized that I was probably too specific in the search terms that I had used earlier.
Now I find that people have been selling / using narrow band sensor simulators for quite a while as a means to "fool" their ECU, after removing their catalytic converters. Maybe with a little more searching, I will be able to find a wideband sensor simulator circuit.

Thanks again,
TonyS


Sat Oct 26, 2013 5:04 pm
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Tony, if you want to "fool an ECU" as opposed to fool a wideband controller, that's a vastly more simple task, just feed it a constant voltage. I'm not lost. Please clarify what exactly you're trying to achieve :-)

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Sat Oct 26, 2013 5:37 pm
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LQFP112 - Up with the play

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Hi Fred,

I seem to have caused confusion by mentioning the narrow-band sensor (I unintentionally do that sometimes : )

I want to fool a wideband controller into thinking that it is successfully controlling a wideband sensor.

Thanks,
Tony


Sat Oct 26, 2013 6:36 pm
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Yes, but why??? :-p Alan answered your question pretty thoroughly from the vague starting point he had. Now I want to know why, what is the actual goal, not some mid point you came up with ;-)

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Sat Oct 26, 2013 7:07 pm
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Wideband Wizard

Joined: Tue Jun 10, 2008 2:53 am
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Narrowband sensors are not controlled, they just output a voltage, wideband sensors need to be controlled so your simulator has to see the control signals sent to it by the controller and respond to those signals. I am assuming that you are using a Bosch IC, so bosch would be the ones who would be most able to help you out, they probably have a simulator already made that they sell.

Now if you made a really good 4.9 simulator, I would advise the company that you are working for to forget about selling the 4.9 controller as they would make buckets of cash selling a simulator, an adjustable simulator with mappable output. I often get requests by people who want to send a fake wideband signal to the ecu so to stop the ECU from adjusting fuel trims, something like this is really valuable in conjunction with a low cost piggyback fuel management unit for ECUs that have native wideband lambda controllers.

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Sun Oct 27, 2013 12:05 am
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LQFP112 - Up with the play

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Fred,
I need to provide some details / guidance to the production test group as to how to test the basic functionality of a wideband controller that is part of a product that I am working on the development of.
Unfortunately, I am not free to provide any other details.

Alan,
The request for a suitable simulator has been made to the controller mfg and we are awaiting their reply.

toalan wrote:
... forget about selling the 4.9 controller as they would make buckets of cash selling a simulator, an adjustable simulator with mappable output. I often get requests by people who want to send a fake wideband signal to the ecu ....
With all your knowledge / experience working with these sensors, is a simulator something that you have considered developing?

Thanks,
Tony


Sun Oct 27, 2013 1:32 am
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Tony, I wasn't asking you for the patent paper :-p I was asking you for linguistic clarity ;-) I think we're all on the same page now.

Fred.

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Sun Oct 27, 2013 1:45 am
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Wideband Wizard

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tony can you send me a pm with your email address, I think I might have a solution for you

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Sun Oct 27, 2013 6:42 am
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