I was curious about the LED's drop voltage or other specs affecting oscillation rate. Everything seems to be in order, but the circuit doesn't work as it should.
I don't see how the LED's would affect oscillation rate.
I'm unsure about the LED's, but the circuit is this:
I don't see how the LED's would affect oscillation rate.
I'm unsure about the LED's, but the circuit is this:
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Oh yeah 
Here it is:
1x NE555 timer IC (or similar 555 timer)
R1 - 100k Ohm resistor (1/4 watt or 1/2 watt)
R2 - 1M Ohm resistor (1/4 watt or 1/2 watt)
R3 - 100k Ohm resistor (1/4 watt or 1/2 watt)
R4 - 10k Ohm resistor (1/4 watt or 1/2 watt)
C1 - 4.7 uF capacitor (rated to at least 15V)
C2 - 22 uF capacitor (rated to at least 15V)
D1 - 1.7V @ 20mA LED
D2 - 1.7V @ 20mA LED
(IMPORTANT: Please make SURE that the LEDs you use are rated to drop 1.7V. If they dont burn 1.7V, then your ECU will have to burn it for them, and that could cause serious damage. They are not simply for appearance!
Here it is:1x NE555 timer IC (or similar 555 timer)
R1 - 100k Ohm resistor (1/4 watt or 1/2 watt)
R2 - 1M Ohm resistor (1/4 watt or 1/2 watt)
R3 - 100k Ohm resistor (1/4 watt or 1/2 watt)
R4 - 10k Ohm resistor (1/4 watt or 1/2 watt)
C1 - 4.7 uF capacitor (rated to at least 15V)
C2 - 22 uF capacitor (rated to at least 15V)
D1 - 1.7V @ 20mA LED
D2 - 1.7V @ 20mA LED
(IMPORTANT: Please make SURE that the LEDs you use are rated to drop 1.7V. If they dont burn 1.7V, then your ECU will have to burn it for them, and that could cause serious damage. They are not simply for appearance!
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My LED's flat part is on the other small or "positive" terminal, but the flat part is the negative terminal.
If I'm reading my multimeter correct in the 2 mA setting I get "0.116" max (mA?)
I hope it's not an amp reading because that would be 116 mA of course?!
What should it be?
Also when the circuit is not connected to the o2 signal wire I get .0 to .9 volts, when the car is running. When I connect the signal out to the o2 sensor input of the ECU, I get .22 to .77 volts with the car running. Seems like my wire needs a ground, no? Will it still work?
Are my LED's the wrong mA rating?
If I'm reading my multimeter correct in the 2 mA setting I get "0.116" max (mA?)
I hope it's not an amp reading because that would be 116 mA of course?!
What should it be?
Also when the circuit is not connected to the o2 signal wire I get .0 to .9 volts, when the car is running. When I connect the signal out to the o2 sensor input of the ECU, I get .22 to .77 volts with the car running. Seems like my wire needs a ground, no? Will it still work?
Are my LED's the wrong mA rating?
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Hi,
The led flat goes to ground. Really what the LED's does it is simulating the O2 sensor voltage. The voltage across the diodes are about .8 volts. If your board it is connected to the car battery you just need to connect the two cables from the LED's and the ground wire. Make sure the voltage output it is less than .8 volts. If the voltage it is below .5 the car it is running rich and it is reading higher than .7 volt the car it is running leading. For a normal reading the voltage should be around .6 volts. The MCU it is looking for a voltage not a current. For a MCU voltage reading the voltage should oscillate between .2 volt to .8 volt.
The led flat goes to ground. Really what the LED's does it is simulating the O2 sensor voltage. The voltage across the diodes are about .8 volts. If your board it is connected to the car battery you just need to connect the two cables from the LED's and the ground wire. Make sure the voltage output it is less than .8 volts. If the voltage it is below .5 the car it is running rich and it is reading higher than .7 volt the car it is running leading. For a normal reading the voltage should be around .6 volts. The MCU it is looking for a voltage not a current. For a MCU voltage reading the voltage should oscillate between .2 volt to .8 volt.
Did I wire this right?
So far it doesn't work.
The circuit oscillated from .77 to .2 VDC when the car is on at .116 mA.
The resistors are 10 ohm for my Passat I think.
The blue wires go to the circuit output. The o2 signal wire or black o2 sensor wire goes to the blue wires.
The brown wires go to the battery ground. The o2 sensor ground or grey o2 sensor wire goes to the brown wires.
The pink ones go to the resistors.
So far it doesn't work.
The circuit oscillated from .77 to .2 VDC when the car is on at .116 mA.
The resistors are 10 ohm for my Passat I think.
The blue wires go to the circuit output. The o2 signal wire or black o2 sensor wire goes to the blue wires.
The brown wires go to the battery ground. The o2 sensor ground or grey o2 sensor wire goes to the brown wires.
The pink ones go to the resistors.
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The wire I used (blue in the pictures) goes to black wire on the O2 sensor harness (if I had one). I don't have black, grey or white wires, just using them as reference from standard O2 wiring. So blue goes to black. Grey is O2 signal ground, goes to brown wires and battery ground. The white ones are the O2 heater circuit. Those go to my resistors. Basically I don't know if grey (O2 signal ground should go to the battery). Also it's strange that I get code P0056, but not P0036 anymore. The circuit goes to both O2 sensor signal inputs, but I only get one code. I checked to see if they are wired correctly. I can tell they are because when you unplug one the voltage oscillation changes slightly.
I don't know what resistance the white wires should have wired in. The resistance in the O2 heater sensor seems to go higher that hotter it is.
8 ohms didn't work, then 10 didn't now I have 18 ohms for each circuit.
I measured one of the front O2 sensors and the resistance was 10.7 when warm and 14.5 ohm when pretty hot.
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I had to design an O2 simulator for calibrating a O2 sensor tester we built once.
Isolate your output to prevent ground loops.
The O2 in your car is isolated and goes to two specific wires to the ECU.
I am not sure why you want to bypass the fuel mixture control loop.
This could result in your engine thinking it was delivering the correct amount of fuel and it is not.
It is not all about emissions. "You could burn up your engine" is not just a story to frighten DIYers.
The DIYers that create their own control over the O2 sensor signal still use an O2 sensor to get a reading of what is happening to the mix.
The usual method for narrowband sensor system is to use a wideband sensor and shift the threshold point to the mix that they need.
Those that want power adjust the threshold for more fuel/air when required.(usually turbo systems)
Those that use them to allow the engine to run on a leaner mix (HHO types) shift the mix point the other way. (researched this quite a bit)
They both know that you still have to monitor what the mix actually is.
Hope you learned something.
Isolate your output to prevent ground loops.
The O2 in your car is isolated and goes to two specific wires to the ECU.
I am not sure why you want to bypass the fuel mixture control loop.
This could result in your engine thinking it was delivering the correct amount of fuel and it is not.
It is not all about emissions. "You could burn up your engine" is not just a story to frighten DIYers.
The DIYers that create their own control over the O2 sensor signal still use an O2 sensor to get a reading of what is happening to the mix.
The usual method for narrowband sensor system is to use a wideband sensor and shift the threshold point to the mix that they need.
Those that want power adjust the threshold for more fuel/air when required.(usually turbo systems)
Those that use them to allow the engine to run on a leaner mix (HHO types) shift the mix point the other way. (researched this quite a bit)
They both know that you still have to monitor what the mix actually is.
Hope you learned something.
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Hi Jimmy. I had a quick look through a list of fault codes for your VW. I found over 30 codes related to o2 sensor range/performance, then stopped counting. Also I'm fairly sure the ECM compares the reading from the front and rear sensors, they are related as they're measuring the same gas. I don't find it "strange" at all that you got rid of one code and picked up another. There's 28 more codes waiting for you.... But best of luck ;-)
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