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Discussion and questions related to the course Understanding AFR
is there a possibillity to show the calibration of the AFR sensor and where to measure the voltage and check the calibration in the ecu is correct
i just want to be sure i understand this and do it the correct way
am i right that when 2.5v is lambda 1 or AFR 14,7 ? maybe you can show this i always use a bosch wideband.
pictures could be already work.
and is it needed if you run a wideband in the ecu that you can log date to always use a externals reading. if the calibration of the wideband is check with the voltage and correct 1 reading should be enough then?
how long will a wideband sensor last and is it needed to recalibrate after let say 10k km or 20k km??
Regards, really like the course so far
Lambda sensors themselves are typically calibrated to a set linear curve from the factory by adding a resistor to correct the value. Depending on your application you may have an ECU with an integrated wideband controller or a standalone wideband controller either way you should be able to adjust the curve in the ECU calibration SW if its required but more often than not the set curve provided in the controller spec sheet should be accurate enough. It's only in extreme humidity and high altitude that these curves can be out slightly. A good sanity check is to saturate the sensor with pure o2 and again with another inert gas such as Argon, both commonly found in workshops. This way you will have 3 data points on the curve 0%, 20% and 100% o2. However its often enough to reference your Lambda value against the test bed sensor when you visit the dyno, if there was only a few points difference I'd be happy.
It's not safe to assume that 2.5v is lambda 1 as this is dependant on what the controller is calibrated to some will use 0.5-4.5v etc, the lambda sensors themselves are typically 10v and output a current value that your controller will turn into a 0-5v analogue voltage or a lambda value over CAN based on the supplied voltage and sensor temperature.
There is always a way to get your lambda value to more than one device either over CAN or 0-5v. Can enabled controllers and ECU's can be daisy chained to gauges, loggers, telemetry etc and the analogue voltage output can be twinned to say an ECU or driver display but take care with wideband analogue voltages as they are particularly susceptible to ground loop offsets. Even ECU's with integrated wideband controllers will usually let you assign and analogue output to lambda.
Traditional lambda sensors, Bosch 4.2/4.9 and NTK don't tend to last into the 1000's on KM's but this is typically an issue with the controller heater circuit rather than the sensor itself. I believe Bosch's latest LSU ADV sensor has been derived from OEM sensors and had its own integrated heater circuit and signal conditioning meaning it should last much longer and be more accurate from 1st start up so it could be worth the investment rather than replacing a 4.9 every few thousand km's
Can you please elaborate on these new breed of OEM sensors?
I thought that Bosch LSU4.2 and LSU4.9 are two sensors that many OEM cars have been running for close to a decade now, no?
For example doesn’t Porsche use LSU (4.2?) and Bosch ECU is in closed-loop at part & full-throttle?
Edit, I've answered my own question: Found more info here: https://www.bosch-motorsport.com/content/downloads/Raceparts/Resources/pdf/Data%20Sheet_69086859_Lambda_Sensor_LSU_ADV/ADV_pre_Turbo.pdf