nice writeup, Warwick. I hope you don`t mind that I add something for the guys who might be interested but are on a budget or don`t see the benefit of getting an LC-2 or the more expensive LM-2 if they only plan to do some adjustments on the Paso once or twice.
There are cheaper solutions that are of course not that sophisticated, but that`ll do the job.
But it can be done even cheaper and all you need is the weld-in bung, a sensor and a voltmeter.
If it`s in working order a used sensor will do fine. It should be one with 4 wires. Two are for the heating, two for the sensor. The manufacturer is not relevant. (the one I`m using is either from my old Fiat Tipo or Audi)
Find yourself a shop that does emission tests, who have an LM-2 or similar equipment.
Set your voltmeter to a low voltage range (i.e. max. 5VDC) and connect it to your sensor. (in parallel to the equipment the shop is using to read the sensor output).
With the engine at operating temperature and at idle adjust the mixture adjusting screw to first 11.8 (0,8La) and write down the voltage from the voltmeter or make a mark if you use an analog instrument. Then do the same for 12.5 (0,85La), then 13.2 (0,9La), then 14 (0,95La). More values are not need, but of course you can write down a few more.
Now you have your own AFR meter.
"La" means Lambda, which is the value we`re mostly using here. For a theoretical full coming burn you need one part of gasoline and 14.7 parts of air. Lambda is the value of supplied air in relation to the theoretically required amount of air. (hence La=AFR/14,7) See table below.
Just forget this info if it`s not relevant for you. I don`t intend to cause any confusion.
The global-tuning takes place basically in driving, because on a test stand only the full load (full power) area is tuned.
An engine has it`s max. performance with approx. 0,88La to 0,90La (rich mixture). The engine has smallest consumption with still acceptable running culture (smoothness) with approx. 0,90La to 0,95La. When accelerating it should be 0,8La, in order to receive a spontaneous acceleration.
With Lambda 1.0 to 1.1 the engine has the smallest pollutant proportions with smallest gasoline consumption, but also a smaller performance with increased gasoline consumption, with increased engine temperature and particularly with miserable runnig culture. At values under 0,7La (very rich) or over 1,2La (very lean) usually the ignition boundary is achieved; the engine stutters.
I do recommend to put some ceramic paste on the sensor plugs to prevent them from seizing.
It doesn`t happen that often but a few guys already lost one so it`s not a bad idea to have them drilled or just saw a small groove in the head and secure them with safety wire.
About the jumpy indicator. Doesn`t the LC-2 or LM-2 have a sensivity adjustment ?
G.