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From Aug 2014
Issues with lambda getting "stuck" at 0.83
Issue with lambda getting stuck when doing a power pull, issue started out of no where and consistently getting worse so the point that I can no longer read lambda under large loads.
Wiring has been checked, and re-checked... Sensor is new.
Sensor had a hard time to calibrate at the beginning (seemed like heater wasn't activating correctly all the time under calibration) I had to start/stop the calibration process a few times in order to get the O2 heater activated for free air cal. Seemed to read fine otherwise and is accurate under light loads @ idle.
Screen shot of log:
Lambda sensor eventually recovers in approx 2-3 seconds of overrun:
Update - Aug 2016
Late last year the owner replaced the WBO2 w/ a new sensor and let me know that it calibrated ok. I wrote the lambda issue off to the sensor after all.
2 Days ago, pre-test race w/ swapped to E98 (from E85) and I noticed the WBO2 was not working at all again. After numerous attempts of free air calibration with the new sensor, the original sensor and one brand new never used O2 sensor. All 3 sensors had the same issue. Durinmg calibration the heater would never stop heating.
Checked wiring again, everything checks out, 12V source is good. I did not have my resistors with me to check the WB output from the ECU so I swapped to a known good ECU and the issue was solved.
It's clear the customers ECU has a defect from HU. Unfortunately it is outside of the warranty period now, but I will be bench testing the ECU and hopefully can be guided to do the repair on the ECU. I'm hoping it is maybe just a bad solder point or driver/IGBT for the WB heater.
UPDATE FEB 2017
I have bench tested the ECU with the following results:
Following test steps listed here: http://megasquirtavr.sourceforge.net/manual/Detailed.Sensor.Wide.html#Operate
Voltage test / ECU ON / WBO2 ON (Heater):
Pin 5 (pump -) + GND = 3.98V (no change to this when adjusting pw_zero up or down - w/ burn + restart of ECU)
Pin 1 (nernst) + GND = 4.41-42V
Pin 1 + Pin 5 = 0.445V
Following tests steps listed here: http://www.vems.hu/wiki/index.php?page=GenBoard%2FManual%2FWBSensorControllerTesting
Voltage Test / ECU ON / WBO2 OFF (Heater):
pump- = 0.0V
GND = -3.97V (again no change when adj. pw_zero)
Voltage Test / ECU ON / WBO2 ON (Heater):
pump- = 0.0V
nernst+ = 0.445V
pump+ = 0.910V
All tests done with correct 100 ohm resistors as stated in the links.
It seems most tests are ok, what stands out is pump- value is lower then recommended 4.1V and will not change up/down when adjusting pw_zero setting at all.
I am at a loss what to check next. All I know is other ECU with Car's wiring is working perfectly. Sensor is not the problem. So issue must be related somehow to this ECU.
ECU SN: 8501