MembersPage/DavidBlades/SenTest (2006-04-30 19:47:06)

Fitting sensors


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)

sensor_cal_sml.jpg

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.

iat.jpg

Coolant and IAT sensor tables have been calibrated manually.

For some reason EasyTherm always produced the wrong answers

AREF for my Genboard is wrong - Fixing it

The value for AREF was wrong, so I fixed it using instructions on BuildProcedures/SectionThree.

However in doing so I clumsily disturbed capacitor C5, so had to replace it. What value should it have been (is it simply a decoupler??) I can't find a list of values anywhere!

At least I can believe the EasyTherm answers now.

The Steinhart-Hart equations were solved (by hand in one case!) and they give the correct temperature for the resistance according to my measurements.

S-H CLT IAT
A 1.22E-036.12E-04
B 2.76E-043.90E-04
C 7.26E-08-4.99E-07

I recorded the temperature reported by the ECU for a selection of known resistances with the original GM curves compiled into the firmware. This let me know what A to D bin each resistance fitted in, so I could then build correction tables using an excel workbook for my sensors and compiled these into the firmware.

[To add: Excel workbooks for calibration]

Recently, I found that the IAT sensor was getting heat soaked. It has been moved from the plenum to the drainpipe where the MAF sensor used to be. The car is much happier with this - and it doesn't get heat soaked as much now.


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.

[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)

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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