ECM fault?

[Programmer]

A slow rolling idle can be caused by an O2 that doesn't react fast anymore
or has become "poisoned". Have you replaced the O2 with a GM one ??--stay
away from the generic O2 sensors. Remember--in "closed" loop, the O2 sensor
is directly responsible for fuel control. The PCM just responds to what the
O2 sends--a biased lean O2 will also command a PCM "rich"--as well as a
biased rich O2 will command a lean condition overall.

Lyndon
-----Original Message-----
From: Akselrud, Boris <AkselruB at moodys.com>
To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
Date: November 8, 1999 10:11 AM
Subject: ECM fault?


>Unfortunately no one answered my first post regarding what I think is ECM
>related problem in 5.7 TBI in my 1993 Cadillac Fleetwood.
>The problem is erratic or I would say unstable idle. Looks like ECM is
>leaning the mixture (don't know for sure) causing idle to go below
>comfortable level for 2..3 seconds followed by 2..3 seconds of smooth
>operation.
>I've gone trough repeated sensors and parameters check on the engine during
>the last two years. I am confident that all the sensors working within spec
>and I scoped the output from all of them. Mechanical condition of the
engine
>is also good - no noices or knocks, compression tests like new, ignition
>system checked repeatedly and spark plugs replaced, no vaacum leaks.
Another
>words the mechanical condition is not at fault. However the output of O2
>sensor at idle is somewhat slow with a period of 2 seconds. I don't know if
>this is normal for that engine.
>Could anyone tell me if you have experienced similar behavior of the engine
>at idle and if you got it corrected. Can it be ECM induced?
>Please, share with me what you can, I have exausted all other sources.
>