Heated O2 sensor scehamtic

[Frank Parker]

> From: michael glidewell <glide at shore.net>
> To: diy_efi at coulomb.eng.ohio-state.edu
> Subject: Heated O2 sensor scehamtic
> 
> I'd like to repalce the non-heated o2 sensor on my 528i BMW with a heated
> one. Anyone know which 3 wire heated sensor would work and what is the
> heating logic I need to put in place?
> ----------------------------------------------

The data sheet for a heated special O2 sensor I am working with makes
special note to avoid applying heater current until after engine has
started and purged any water condensation etc from pipes. Thus should
also be mounted frpm 9am to 3 pm position on pipe and not at bottom where
it could get water. Sensor has a limit of temp delta of 300 deg K per sec
which if were heated to 650 degC and got hit by water, would exceed and
possibly cause cracking of ceramic substrate.
I am setting a 30 sec delay for mine control circuit.

I do believe that most production cars do not have delay, but have not 
looked at diagram to check.

frank parker
>