Whats a lambda?
#1
#3
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#4
The Lambda Sensor (exhaust gas oxygen - O2 sensor) is the key sensor in engine fuel control management. The ECM (Engine Control Module) uses the O2 sensor’s input to balance the fuel mixture, making it leaner when the sensor reads rich and richer when the sensor reads lean.
Lambda Sensors produce a voltage signal that recognises the amount of unburnt oxygen in the exhaust. The voltage varies according to the amount of oxygen in the exhaust compared to the ambient oxygen level in the air. The bigger the difference, the higher the sensor’s output voltage.
Sensor output ranges from 0.2 volts (lean) to 0.8 volts (rich). A perfectly balanced or "stoichiometric" fuel mixture is 14.7 parts of air to 1 part of fuel. This gives an average reading of around 0.45 volts.
The Lambda Sensor’s output voltage doesn't remain constant but cycles from rich to lean approximately once per second. In a new sensor, this transition takes around 100 milliseconds. As the sensor ages, the transition takes longer which is why sensors need replacing at around 100K miles.
Lambda Sensors only operate when hot (above 250 deg C). To reduce the warm-up time of the sensor, an internal heating element is used. These are Heated Oxygen Sensors (HO2S) which can reach an operating temperature of around 500 deg C in less than 10 seconds.
Shorter warm-up time means the system goes into closed loop faster which reduces emissions and improves fuel economy.
Graham
Lambda Sensors produce a voltage signal that recognises the amount of unburnt oxygen in the exhaust. The voltage varies according to the amount of oxygen in the exhaust compared to the ambient oxygen level in the air. The bigger the difference, the higher the sensor’s output voltage.
Sensor output ranges from 0.2 volts (lean) to 0.8 volts (rich). A perfectly balanced or "stoichiometric" fuel mixture is 14.7 parts of air to 1 part of fuel. This gives an average reading of around 0.45 volts.
The Lambda Sensor’s output voltage doesn't remain constant but cycles from rich to lean approximately once per second. In a new sensor, this transition takes around 100 milliseconds. As the sensor ages, the transition takes longer which is why sensors need replacing at around 100K miles.
Lambda Sensors only operate when hot (above 250 deg C). To reduce the warm-up time of the sensor, an internal heating element is used. These are Heated Oxygen Sensors (HO2S) which can reach an operating temperature of around 500 deg C in less than 10 seconds.
Shorter warm-up time means the system goes into closed loop faster which reduces emissions and improves fuel economy.
Graham
Last edited by GGG; 03-05-2014 at 10:47 AM.
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#5
Graham:
Great write up except the part defining the voltage levels for the sensors. The article you posted is , I assume. referring to zirconium lambda sensors. The X-300 uses titania sensors which are resistive devices that operate in substantially the same way as zirconium ones, but at different signal levels.
Great write up except the part defining the voltage levels for the sensors. The article you posted is , I assume. referring to zirconium lambda sensors. The X-300 uses titania sensors which are resistive devices that operate in substantially the same way as zirconium ones, but at different signal levels.
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#11
Rather than just changing them, why don't you get yourself a cheap (~$20!) OBD2 dongle so that you can have a look at how well your lambdas are working?
I use a bluetooth one paired with my android phone and a couple of free apps, but there are various wired and wireless dongles that can be used with laptops etc. You can draw graphs of direct sensor output, look at the resulting fuel trims, log all the info you like onto a spreadsheet...
Everyone (I assume it can't just be me!) loves new tools & this must be the best value tool I've ever bought... well that or my favourite (biggest) hammer, anyway.
I use a bluetooth one paired with my android phone and a couple of free apps, but there are various wired and wireless dongles that can be used with laptops etc. You can draw graphs of direct sensor output, look at the resulting fuel trims, log all the info you like onto a spreadsheet...
Everyone (I assume it can't just be me!) loves new tools & this must be the best value tool I've ever bought... well that or my favourite (biggest) hammer, anyway.
#12
The Lambda Sensor (exhaust gas oxygen - O2 sensor) is the key sensor in engine fuel control management. The ECM (Engine Control Module) uses the O2 sensor’s input to balance the fuel mixture, making it leaner when the sensor reads rich and richer when the sensor reads lean.
Lambda Sensors produce a voltage signal that recognises the amount of unburnt oxygen in the exhaust. The voltage varies according to the amount of oxygen in the exhaust compared to the ambient oxygen level in the air. The bigger the difference, the higher the sensor’s output voltage.
Sensor output ranges from 0.2 volts (lean) to 0.8 volts (rich). A perfectly balanced or "stoichiometric" fuel mixture is 14.7 parts of air to 1 part of fuel. This gives an average reading of around 0.45 volts.
The Lambda Sensor’s output voltage doesn't remain constant but cycles from rich to lean approximately once per second. In a new sensor, this transition takes around 100 milliseconds. As the sensor ages, the transition takes longer which is why sensors need replacing at around 100K miles.
Lambda Sensors only operate when hot (above 250 deg C). To reduce the warm-up time of the sensor, an internal heating element is used. These are Heated Oxygen Sensors (HO2S) which can reach an operating temperature of around 500 deg C in less than 10 seconds.
Shorter warm-up time means the system goes into closed loop faster which reduces emissions and improves fuel economy.
Graham
Lambda Sensors produce a voltage signal that recognises the amount of unburnt oxygen in the exhaust. The voltage varies according to the amount of oxygen in the exhaust compared to the ambient oxygen level in the air. The bigger the difference, the higher the sensor’s output voltage.
Sensor output ranges from 0.2 volts (lean) to 0.8 volts (rich). A perfectly balanced or "stoichiometric" fuel mixture is 14.7 parts of air to 1 part of fuel. This gives an average reading of around 0.45 volts.
The Lambda Sensor’s output voltage doesn't remain constant but cycles from rich to lean approximately once per second. In a new sensor, this transition takes around 100 milliseconds. As the sensor ages, the transition takes longer which is why sensors need replacing at around 100K miles.
Lambda Sensors only operate when hot (above 250 deg C). To reduce the warm-up time of the sensor, an internal heating element is used. These are Heated Oxygen Sensors (HO2S) which can reach an operating temperature of around 500 deg C in less than 10 seconds.
Shorter warm-up time means the system goes into closed loop faster which reduces emissions and improves fuel economy.
Graham
#13
Where did you find one? My '95 XJ6 is it OBD1 or OBD2?
Rather than just changing them, why don't you get yourself a cheap (~$20!) OBD2 dongle so that you can have a look at how well your lambdas are working?
I use a bluetooth one paired with my android phone and a couple of free apps, but there are various wired and wireless dongles that can be used with laptops etc. You can draw graphs of direct sensor output, look at the resulting fuel trims, log all the info you like onto a spreadsheet...
Everyone (I assume it can't just be me!) loves new tools & this must be the best value tool I've ever bought... well that or my favourite (biggest) hammer, anyway.
I use a bluetooth one paired with my android phone and a couple of free apps, but there are various wired and wireless dongles that can be used with laptops etc. You can draw graphs of direct sensor output, look at the resulting fuel trims, log all the info you like onto a spreadsheet...
Everyone (I assume it can't just be me!) loves new tools & this must be the best value tool I've ever bought... well that or my favourite (biggest) hammer, anyway.
#14
#15
This is the main reason it's a good idea to have the vehicle tested with the engine up to temperature.
Graham
#16
Join Date: Sep 2008
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95 jags are OBD2. when running a inspection I have to lie and say its a 96 to get it to run a regular plug n play OBD2 test since OBD2 were not required till 96 and state machines here in Texas still list 05's as OBD1 which is a longer more PIA test. Jaguar came out with OBD2 a year before required in the US
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