Lambda Value

[Andy Wyatt]

Regarding Gareth's question about O2 sensors..

I know a very little about EGO sensors, which I learnt from an article in
Silicon Chip electronics magazine (in Oz), November 1995. It show a graph of
voltage against Lambda for a "typical" sensor. It says with a lambda of
0.94, it will develop a voltage of a bit over 0.9V. The graph isn't very
well calibrated, so it ain't very useful, but from what I can tell your
typical EGO sensor is only really accurate around stoic. Even then there is
hysteresis, which means that the curve you trace out is a different shape
when going from rich to lean from the curve going from lean to rich. The
graph is VERY steep around stoic point, then it becomes quite flat at lambda
values below 0.96 and above 1.05.

This is only for a typical EGO sensor, which is only designed to work around
stoic, so that EFI cars can keep their emissions down. You can get wideband
EGO sensors, which are fairly expensive, from what I hear.

If it's any encouragement, though, I've just tuned my ECU by using an EGO
sensor which I got from a wrecker (actually it was free, it was on the
exhaust manifold of an engine I bought), and though I have no idea of how
accurate it is, it seemed to work OK.

Have a good one
Andy W :-D