- After #10267 was replaced with new ECU #15379, after some minutes you are using the car, and more quickly if running it hard, lambda sensor stops working, lambda gauge on VT goes to max lean 1.83 and CEL switches on.
- Everything returns fine again for few minutes if you switch off and on the engine.
- most often related to failed sensor, or misconfigured. Eg. free air calibration was forgotten
- Free air calibration was correctly done.
- Sensor is 4.2, placed in the front pipe, 1 meter from exhaust valves (oem place).
- Ecu was configured accordingly with values provided in the new ecu sheet.
- most often related to failed sensor, or misconfigured. Eg. free air calibration was forgotten
- if sensor heating is a bit weaker (cannot reach target) for any reason, might need to up-adjust WBO2 heater abs limit (up to 255).
- Ok, will try... but the fact it happens more often when using the car hard (so higher egts) would make me think it's not weak heating related?
- Is there a way, looking at the logs, to understand what's going wrong in lambda sensor/v3 ecu controller?
- capture vemslogs during sensor [free air calibration].
- Also during the "some minutes" the symptom shows up
- Vems logs and cfg:
- log https://www.datafilehost.com/d/87ac3205
- logreview, this log is of engine running not wbo2 calibration in free-air (log enabled before starting wbo2 cal and running 3-4min past pump enable), please provide such a log so we can diagnose and assist you in resolving this matter - DB
- old ecu cfg https://www.datafilehost.com/d/84045bc7
- new ecu cfg https://www.datafilehost.com/d/f848864e
- What is sensor measured Rcal (Ohm) value ?
- Will discover asap, car is 400 kms away
- Is the ECU configured for LSU4.9 ?
- If LSU4.9 sensor, see [LSU4.9 pdf]
- for LSU4.9 is the 27k (or 27k4) nernst pullup installed inside ECU, or outside in the harness ? What DC voltage is measured across known and documented value (1k .. 10k) pulldown resistor between nernst and GND ? (with sensor disconnected, ECU on, but engine off)
- That measurement is important. New ECU-s are, by default made with this 27k nernst pullup to support LSU4.9 sensors. No side effects have been experienced with LSU4.2 (if otherwise configured properly) but need to know the details anyway.
- upload the vemslogs (captured during calibration and "some minutes the symptom shows up"), annotate the most interesting time window of each log
- Unfortunately no free air calibration log, only "some minutes" when CEL was on and off and on, and lambda sensor not working
- I may add that this happened after old VEMS ECU was replaced with new, and never happened in 2500 kms with the old board.
Current fw is 1.2.38.
- What was old fw ? 1.2.31 ?
- Maybe related to some unintentional side effect of upgrade ?
- important: upload old config and new config please, so we can compare.
- Unfortunately I don't remember the fw you put in the #15379, but I needed to upgrade for the lack of AC request idle up function.
- Support for ecu serial #10267
- A customer's V3.6 ecu suddendly lost serial number, seems to be in a kind of limp mode (10° and 0.65 lambda at any load/rpm).
- VemsTune is now displaying that Serial is unknown-0.
Granting (by info sent in priv),
Do you have ISP cable (Parport DSUB25 or USB-ISP ?) Will need to follow
http://vems.hu/vt/help/v3/general/bootloader_upgrade.html
If considering bootloader upgrade, (so that internal BOD can be disabled) highly recommended:
PLEASE CHECK THAT v3/10267 has reset chip at the atmega128/pin20 reset, eg
- mcp121 or mcp131 (U26 position)
- or mcp809 or max809 (U10 position)'''
See GenBoard/VerThree/Schematic eg
- Support required for VEMS EGT amplifier
Engine off, ambient sensor temp (~20C)
- Tested Pin7 DVM output (1V/100°C) and getting 0.7 volts
- corresponding to 70C
- not 6 volts, roughly corresponding to Pin6 2.5 volts.
- I'm getting 2.5 volts out of Pin6 (0-5V output, 1V/233.3C)
- Thus getting 580°C instead of 20°C.
Hint: The output is almost certainly connected to an input with pullup (possibly strong pullup).
- Diagnostic: disconnect anything from output, and measure DC voltage with DVM (the DVM has 1 to 10MOhm input impedance).
- Solution: make sure to connect pin6 output to an input without pullup resistor
Sensor connection (seems good):
EGT sensor is K type yellow-red wires:
- yellow = green (plus wire) to board GND
- red = white (minus wire) to the board cathode on corner