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Sending a narrow band signal to your 87-89T with LC1-LM1...

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  • Sending a narrow band signal to your 87-89T with LC1-LM1...

    If I am understanding the O2 sensor thing on the z31's correctly it is that 84-86 uses a voltage o2 sensor and the 87-89 uses a resistor type o2 sensor. Is this correct?

    Assuming this is correct, How are you guys sending a narrow band signal to the stock computer if you were running the resistor type sensor? Meaning how does the 87-89 ecu interperate the info from say a wide band controller that sends out the narrow band signal.
    85 Z31 6.0 LSX turbo 766whp/792wtq
    04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

  • #2
    the full chart of o2 sensor types is on jason's ecu pages... but I seem to remember the innovate stuff has a seperate port to imitate one

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    • #3
      Well, 86 turbo and non-turbo use a titania resistive O2 sensor.
      Try not to be a Yahoo

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      • #4
        crowbar wrote: Well, 86 turbo and non-turbo use a titania resistive O2 sensor.
        Right, so do the 87-89 turbos. So how would an LM-1 that normally puts out a narrow band signal in terms of voltage, send a resistance signal to the ecu, since that how the ecu measures afr's on the 86-89 turbos?
        85 Z31 6.0 LSX turbo 766whp/792wtq
        04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

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        • #5
          I'm pretty certain there would be some slight ecu modifications involved. IfI remember correctly the titania sensor acts as part of a voltage divider circuit that probably feeds to the ad converter. My guess is that you would need to remove part of the divider circuit and rig it so the lm-1 feeds a voltage directly to the ad converter.

          Honestly I would keep the stock narrowband sensor connected to the ecu. I know thats not what youre asking but I feel the stock sensor is generally more reliable. Theres also no advantage to using the lm-1 as the input since the ecu isnt able to get any better data from it over the narrow band. In this case I feel keeping it simple is the way to go.

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          • #6
            Stinky is correct on many points.

            I actually think the wideband response and other characteristics are inferior to a narrowband around stoic.

            If I were to buy one of these widebands, I would actually use a narrowband to calibrate the wideband around stoic. This would be done at many RPM points.
            Try not to be a Yahoo

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            • #7
              Well its not somthing I was looking at doing. My buddy has an 88turbo but he is running a 85 turbo ECU so his O2 situation doesnt even work right now and he just runs rich. But he was asking me that if he got a lm1 or somthing if we could send the signal to the ecu. I said most likley since he is running the 85 turbo ecu. we would just have to find the right pins going into the ecu.

              But thats what got me wondering how would you do it on an 88T that still has the stock ecu? Either way. I was just curious as to what some of you guys would have to say about that. Sounds like its more work that its worth.
              85 Z31 6.0 LSX turbo 766whp/792wtq
              04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.

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              • #8
                SATAN wrote: Well its not somthing I was looking at doing. My buddy has an 88turbo but he is running a 85 turbo ECU so his O2 situation doesnt even work right now and he just runs rich. But he was asking me that if he got a lm1 or somthing if we could send the signal to the ecu. I said most likley since he is running the 85 turbo ecu. we would just have to find the right pins going into the ecu.

                But thats what got me wondering how would you do it on an 88T that still has the stock ecu? Either way. I was just curious as to what some of you guys would have to say about that. Sounds like its more work that its worth.
                there are actually some pretty cool things you can do with the narrowband output on the widebands... for example.. i cruise very lean at like 16-1.. unfourtunatly the stock narrowband cant correct that lean, so im not in closed loop.. now suppose you recalibrated the lm1 output to tell the ecu that 16-1 was stoich.. now you would have the accuracy of closed loop at a much leaner afr and get an even greater increase in gas mileage. im willing to get that 30+mpg highway is possible with this setup.. but like you said, how does it work with the newer ecus?

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                • #9
                  I would be very interested in seeing that.

                  The stock ecu does dither about a voltage that corresponds to 14.7:1. It actually slews up and down the steep slope of the stoich voltage as a control scheme.

                  This same scheme, applied to wideband would require the same steep variation. In other words, the ecu would be running at cruise and the afr would be going back and forth from one ratio to another. How much of a variation in ratio would be interesting. You might get as much as 0.15 volts away afr (whatever that is in wideband response).

                  The wideband response had better be damped. Or there will be oscillations as well. Your car would had a surge of sorts.

                  By the way, if running at 16:1, I hope you have your egr attached. Because you are pumping out NOx like crazy.
                  Try not to be a Yahoo

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                  • #10
                    If one really wanted to run the LM1 into a titania ecu, or just a zirconia O2 into a titania ecu, then a simple switching scheme might be used.

                    The output of the voltage producing O2 sensor is used to switch on a transistor. The transistor has a resistor between the emitter and ground. When the transistor is not on, the resistance is very high (another large value resistor could be in parallel providing this. When the transistor is on, then the smaller valued resistor is 'seen'.

                    A very simple circuit.
                    Try not to be a Yahoo

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