DIY_EFI Digest V5 #39,toyota o2

[Scott_Hay at toyota.com]

Date: Tue, 25 Jan 2000 13:08:37 -0700
From: bearbvd at cmn.net (Greg Hermann)
Subject: Re: Greddy air-fuel ratio meter

>Almost looks good, anyone have any details about the 4 wire Toyota O2
>sensor, the tech guy at greddy's said it can read 18-8:1, but not to be used
>for initial tuning????.
>They want $300, for theirs.
>Grumpy

Sounds like it must be the Bosch sensor--that one uses four wires--anybody
know for sure??


Grumpy/Greg

The Toyota sensor can in fact measure a broad range of a/f ratios but so far,
there is little information we have in the US as to how it actually works.

The sensor does have 4 wires, B+ for heater, ground for heater - controlled by
ecm (pwm), afr+ which supplies +3.3v from the ecm to one side of the sensor, and
afr- which the ecm supplies +3.0v to the other side of the sensor.

We do see a variable voltage when using a scanner tool but when you measure the
sensor itself, voltage is not moving with major shifts in afr????  The general
thought is that it  monitors the amperage and the direction of current flow to
determine the afr. The scan tool voltage is a calculated # to give diagnostic
functions.

Very good and incredibly accurate sensor which operates in a linear fashion to
afr.

This will probably add more questions than it answers but it is a start.

Scott
>


----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org