Date:         Tue, 13 Feb 2007 10:20:11 -0800
Reply-To:     Mike Frost <wasserleaker@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Mike Frost <wasserleaker@GMAIL.COM>
Subject:      ECU reset, O2 voltage stability
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Greetings all,

It's time for smog testing on my 86 2.1L and I am failing for HC and CO. So
I am looking closely at the O2 sensor which was very recently replaced.

My first question is about the Digifant I ECU. I have read many differing
statements about resetting or clearing the memory of the ECU. Does the ECU
have any kind of static RAM (memory that does not lose its contents on
power-down)? Does the computer reset completely when the ignition is turned
off? Some things I have read talk about entering 'service mode' by
disconnecting the temp II sensor and then 'blip' the throttle 3 times up to
3000RPM (or 4 times up to 2500). I can believe that there is a service mode,
but I'm having trouble believing that the ECU can 'remember' the state of
the ignition system after the engine is shut down.

Second question involves the voltage from the O2 sensor. Under idle
conditions (no change in RPM) I am seeing the voltage swing down to zero and
then back up again to some value above 0.5V when the O2 is connected to the
ECU. Is this normal? I'm guessing that I should see a fairly stable voltage
unless the speed of the engine changes.

Thanks in advance,

Mike
wasserleaker@gmail.com