Diy o2 sensor manipulator - KTM Duke 390 Forum
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post #1 of 5 Old 09-01-2018, 09:21 AM Thread Starter
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It is very easy to do a lambda manipulator, a device that "tricks" signal from lambda sensor in order to enrich mixture. You have to make a voltage divider (see picture below).: as z1 I used 1kOhm, z2 4,7 kOhm. V input comes from lambda black wire, V out the black wire lambda to ECU. As ground you can use the grey wire from stock lambda.

There are some lambda manipulators for sale (ie fat duke), but I didn't like the resistor ratio (1/2) because it lowers too much signal to ECU. A narrow band lambda at closed loop produces voltage from 0.2 to 0.85 V. A ratio of z1/z2=1/2 lowers about 40% the signal to ECU, ie from 0.85 volt to 0.5V. I tested the 1/2 ratio, the bike seemed to be sluggish and had exhaust explosions from unburned fuel. I used 1/5 ratio that lowers signal about 20% and tested again the bike, was better. No check engine, no hesitation, better response, like if I had installed a rapid bike easy. I have done all the connections without soldering, just tying together the wires with resistors and using tape.

Make sure to mark each cable in order not to mix them and tie the wires very well in order to avoid fire!


I also used 2 new connectors in order to install the voltage divider "plug and play", and can put back stock lambda wires without cutting and connecting wires.
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Last edited by duke200; 09-01-2018 at 09:31 AM.
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post #2 of 5 Old 09-01-2018, 07:26 PM
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Quote:
Originally Posted by duke200 View Post
It is very easy to do a lambda manipulator, a device that "tricks" signal from lambda sensor in order to enrich mixture. You have to make a voltage divider (see picture below).: as z1 I used 1kOhm, z2 4,7 kOhm. V input comes from lambda black wire, V out the black wire lambda to ECU. As ground you can use the grey wire from stock lambda.

There are some lambda manipulators for sale (ie fat duke), but I didn't like the resistor ratio (1/2) because it lowers too much signal to ECU. A narrow band lambda at closed loop produces voltage from 0.2 to 0.85 V. A ratio of z1/z2=1/2 lowers about 40% the signal to ECU, ie from 0.85 volt to 0.5V. I tested the 1/2 ratio, the bike seemed to be sluggish and had exhaust explosions from unburned fuel. I used 1/5 ratio that lowers signal about 20% and tested again the bike, was better. No check engine, no hesitation, better response, like if I had installed a rapid bike easy. I have done all the connections without soldering, just tying together the wires with resistors and using tape.

Make sure to mark each cable in order not to mix them and tie the wires very well in order to avoid fire!


I also used 2 new connectors in order to install the voltage divider "plug and play", and can put back stock lambda wires without cutting and connecting wires.
Interesting
Can you please add some pictures from your installation? And maybe info about the plugs (picture, name)
Did you consider using a potentiometer? Then you would be able to change the value easily.
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post #3 of 5 Old 09-02-2018, 02:27 AM Thread Starter
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I tested some resistors for z2, (2k, 3k, 8.2k). Yes, It would be better if the z2 was a potentiometer, but with z2 4.7k there isn't much interference to signal, but I saw big improvement. I believe z1/z3 ratio less than 1:3 (ie 1/2 or 1/1.5) would add to mpg without any essential gains. In my opinion you would be needing 1/3 if you had open air lid and total free exhaust.

I am sorry I didn't think of taking pics while building it, so I took some pictures now. The green connector is stock to ecu.

Connectors was cheap stuff, I bet you will find at any electronics store, like radio shack. As you noticed, I used female-male , cable , female-male structure in order to be able to remove easily the divider and put back stock lambda with one white connector
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Last edited by duke200; 09-02-2018 at 02:31 AM.
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post #4 of 5 Old 03-02-2019, 07:45 AM Thread Starter
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After almost 8 months of using the diy manipulator, all ok. Only Once I had an ecu error "lambda sensor wiring harness" after one month of the installation, code erased , since then the ecu learned to live with the manipulator.
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Last edited by duke200; 03-02-2019 at 07:52 AM.
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post #5 of 5 Old 04-15-2019, 07:04 AM
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That’s a good result, and it’s saved you UKú140 for the RBE tuning box.
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