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Old 03-28-2006, 11:27 PM   #1
NavyBlueSubaru
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Default Can the TxsTuner replicate the stock af sensor?

I was wondering if anybody has done this. I think the tuner has a wideband output on it that can be configured for narrowband as well. Cant this signal be spliced into the stock harness, permitting you to run without the stock af sensor completely? Ignoring cells, blah blah, can it be done?

Also you'd have to block off the spot in the headers where the stock sensor was.

Dont you think the lack of a sensor would increase the flow of the headers? You cannot argue that it isnt in the way of the exhaust gases and restricting flow, but how much is harder to figure out.

To remove the sensor would cause the exhaust gases to flow easier through that portion of the pipe, maybe only 5% but perhaps maybe 20%, who knows? You definitely wont Lose any power, only gain.

Jeff
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Old 03-29-2006, 12:54 AM   #2
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RTFM

Quote:
Analogue Output Mode
(0=Wideband,
1=Narrowband)
When set to 0, the above scaling values are used.
When set to 1, a simulated narrow band signal is output. When
richer than stoichiometric, approximately 0.9V is set on the
output. When leaner than stoichiometric, the output is set to 0V.
Or just use a voltage divider if you want the resolution of a wideband as much as possible in a 0-1v signal. And no you won't gain squat from removing the front O2 sensor. Probably just piss off the stock ECU because the heater circuit would be left 6 feet under.
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Old 03-29-2006, 10:08 AM   #3
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yes ive done it for the rear O2.

you can also get a "heater" sim which is just a big resistor.





http://mysite.verizon.net/vze7erz1/id10.html

Quote:
Wire wound power resistor
Resistance: 50 ohm
Power rating: 25 watt
Length 2 in.
Diameter 0.65 in.

$5.50 each
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Old 03-29-2006, 03:33 PM   #4
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aaronwrx, it looks like you simulated the rear sensor. What about the front? thats what im interested in doing.

Jeff
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Old 03-29-2006, 03:54 PM   #5
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Quote:
Originally Posted by NavyBlueSubaru
aaronwrx, it looks like you simulated the rear sensor. What about the front? thats what im interested in doing.

Jeff
Yes this was for the rear. I have no idea about the front but it probably works the same way. pull back some of the cable wrap and see if there are 4 wires.
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Old 03-29-2006, 04:53 PM   #6
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Front sensor is not the same as the rear. The front is not a standard narrowband. From previous discussions on the sensor, I doubt the tuner could drive it.
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Old 03-29-2006, 10:17 PM   #7
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Quote:
Originally Posted by KGreb
Front sensor is not the same as the rear. The front is not a standard narrowband. From previous discussions on the sensor, I doubt the tuner could drive it.
He's not talking about driving the sensor, he's talking about sending a 0-1v narrowband signal to emulate the stock front sensor. FWIW I don't know if its a 0-5v signal or not, I don't remember right now. But what he is talking about can be done on the Tuner.
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Old 03-29-2006, 10:46 PM   #8
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Yea, I want to remove it and have the tuner spoof the stock ecu by simulating the front 02. The only problem I can think of is the warm-up period...what does the tuner output during that time?

Jeff
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Old 03-29-2006, 11:50 PM   #9
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Stock front sensor doesn't measure 0-1v. Shop manual on my '05 shows 2.8-3.2v on the positive signal, 2.3-2.7 on the negative at idle. From the description it sounds like the ECU is driving a specific voltage (which is not static) and expects a range of current outputs. You would need to spoof the current, not voltage, if this is correct.
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Old 03-30-2006, 12:42 AM   #10
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Quote:
Originally Posted by NavyBlueSubaru
Yea, I want to remove it and have the tuner spoof the stock ecu by simulating the front 02. The only problem I can think of is the warm-up period...what does the tuner output during that time?

Jeff
Doesn't matter because the stock O2 isn't giving feedback before it warms up anyway.

Quote:
Originally Posted by KGreb
Stock front sensor doesn't measure 0-1v. Shop manual on my '05 shows 2.8-3.2v on the positive signal, 2.3-2.7 on the negative at idle. From the description it sounds like the ECU is driving a specific voltage (which is not static) and expects a range of current outputs. You would need to spoof the current, not voltage, if this is correct.
So it is 0-5v signal. It should be around 2.3-2.7 which means its at stoich. Give it a quick blip of the gas you will see it go whacked out.
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Old 03-30-2006, 06:31 AM   #11
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Quote:
Originally Posted by KGreb
Stock front sensor doesn't measure 0-1v. Shop manual on my '05 shows 2.8-3.2v on the positive signal, 2.3-2.7 on the negative at idle. From the description it sounds like the ECU is driving a specific voltage (which is not static) and expects a range of current outputs. You would need to spoof the current, not voltage, if this is correct.
You are correct the front O2 is current based. The Tuner can not replicate a current sensor only voltage sensors.

TMS
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