Fitting sensors
- The car already has usable CLT and TPS sensors.
- There's a connection on the plenum all ready for MAP
- There's no IAT sensor at the moment
- I will be removing the old MAF sensor
- Old narrowband sensors are not good as they are titania type and too expensive - they have been replaced with a pair of LSU widebands.
Testing the Sensors
I've bench tested the NTC sensors and they work in pots of water at varying temperatures. Here's a picture of my "lab" (kitchen)
I need to add a IAT sensor to the plenum somewhere. Found one in a scrappy for £1. It works nicely. Here's a shot of it installed in the plenum.
I have recompiled the firmware for the non-GM CLT & IAT sensors. Need to refine the calibration more as the IAT isn't quite right yet.
Wideband Lambdas
I have done some work on the exhaust so the widebands will fit. Two new bosses have been welded in as the LSUs are bigger than the old sensors.
I've fitted two - one for each bank.
We need to modify the firmware for the 2nd to be supported. Until than, I get that to work, since the LSU4 sensor would be ruined due to deposits if unheated:
- possible to connect the heater to the same output as the first sensor (parallel connection). In this case, 10A instead of 5A fuse is reasonable.
- or: running with one, and the other hole blanked off with a (blindplug or) an old lambda sensor. (this is best).
[Add pic of modded exhaust]
Firmware mods for 2 widebands
We have some code in the round to be backported (mostly prepared for 2 channels, but some more changes still needed)
- adc.c irq handler
- wbo2.c
- reworked/cleaned up some parts
- we saved some SRAM and even config variables.
- Filtering change for even lower latency
- comm.c and lcd_display.c : log and display the new variables
- fuelcalc.c : for the 2 independent ego-correction, we need to know which cylinders belong to each bank.
- Only reasonable with camsync ?
- Megatune changes
- At least pump_pw_zero could be independent for the second sensor.
- some variables like max-heat and friends could be dropped, and calculated from battery voltage
- Currently reading the firmware code to see if I can work this one out for myself...
- it's unlikely you would want to do this yourself. If you have much sparetime, work on the (SPI=>) MMC logging (and we'll get the 2nd wbo2 channel: for better project efficiency, since wbo2 is simpler for us, while MMC is same amount of work for us as for you)
Calibration of WBO2
This is well documented in the wiki and manual, but the q & a here is interesting to keep.
The cal resistor in the wideband sensor is NOT connected. We use the wbo2_calibration setting in firmware instead of the cal resistor. Just measure the cal resistor for verification
A: The calibration resistor is not used in the v3.x wideband controller implementation, calibration is done trough adjustment of the calibration constant until your free-air o2% matches 20.95%. However, measure and document Rcal (allows verification of wbo2_calibration value). Don't forget that wbo2_calibration value is sensor dependent.
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