Sunday 27 January 2013

Lambda sensor

There is plenty of opinion on Lambda sensors & prevailing knowledge from both GBS and the forums is they are not necessary once the engine has been mapped on a rolling road.

GBS also rekon the stock Power & Emissions maps are good enough to get through the IVA - although might need a little tweaking during the test.

I didn't want to invest in a wideband sensor, but like the idea of developing an emissions/economy map which 'knows' what is going down the exhaust. My ultimate plan is two maps:

  1. Emissions & economy running the narrow band lambda at 14.7 AFR
  2. Power map - initially the GBS one and maybe a rolling road tuned one later
The narrow band setup is much more reasonable & apparently longer lived than wideband, but much more limited in how it can be used - it really only measures 14.7 AFR.

Challenge #1 was to identify the Lambda plug on the GBS stock loom - its a Deutsch DTM & I found one being sold on Ebay for less than a tenner. The pins are meant to be crimped with a proprietary Deutsch tool which sells for £200 ! -  instead I crimped with pliers and added a small solder end for good measure - being careful not to let the solder wick back up the cable:


Screws into the manifold & then just needs a hole & grommet through the side panel back into the engine bay. I attached the pins to the cables on the bench then passed through the side panel for the socket assembly:

For IVA the sensor and sharp edges will need a little exhaust wrap.

Connections are thus:

Belt & braces working out the wiring - I traced & tested the loom cabling back to the ECU and as expected it was correctly terminated on the default pins.

     Lambda Signal - Sensor: Black  - Plug: Red                   - ECU: pin 7
     Signal Ground  - Sensor: Grey   - Plug: Blue                   - ECU: pin 18
     Heater Control  - Sensor: White - Plug: Green & White - ECU: pin 36
     Heater 12v        - Sensor: White - Plug Black                 - 12v switched feed


The loom routing: