[Diy_efi] O2 says rich, car runs lean..

[Arby]

Where can you find an O2 sensor like this?  I would need it to work with a
1227747 computer and something inexpensive would be best (obviously).

Thank you,
Arby


----- Original Message ----- 
From: "Michael Richards" <michael at fastmail.ca>
To: <diy_efi at diy-efi.org>
Sent: Sunday, June 11, 2006 8:43 PM
Subject: Re: [Diy_efi] O2 says rich, car runs lean..


> On Sun, 11 Jun 2006 15:45:28 -0700 (PDT), David Rowley wrote...
>
> First of all I have to say that tuning with a narrow band O2 sensor is
> useless. I've been tuning for almost 7 years not and have to constantly
> educate people about the inaccuracies of narrowband sensors.
>
> Second, your readings may be related to the position of the O2 sensor.
> If you overheat a narrowband they will frequently read rich when in fact
> you're running lean. This too can sometimes be caused by an ignition
> timing issue too much retard will over heat the sensor as well. If you
> accidentally put it after a cat then that too will cause incorrect 
> readings.
>
> My suggestion is to replace the narrow band with a wideband that also
> has a narrow output. This way you can have a proper temp-compensated and
> accurate O2 reading converted to narrow band plus have a proper mixture
> display on the dash. The 383 should like somewhere in the 13:1 under
> power and should run just fine in the low 15's under cruise. If you
> properly balance all 8 cylinders with a pyrometer you can run it leaner
> without any ill effects for fuel economy.
>
> -Michael
>
>> I have a chevy 383 motor with Vortec Heads, GMPP hot cam (218-228
>> duration, roller), Edelbrock RPM Air gap manifold and a Holley 670
>> throttle body injection unit.
>>
>> I have a problem where the car runs and idles great, until it goes to
>> closed loop mode.  When this happens, the ECM starts leaning out the
>> AFR (the block learn goes down the minimum, 108 in this case) to the
>> point where it will barely run.  Why is the O2 seeing a rich mixture
>> when it appears it is not?  I have tried two O2 sensors with the same
>> result.  Does it have to do the the cam duration and manifold type?
>>
>> I have tuned a few vehicles and I have always been able to rely on the
>> O2 sensor ( with the Integrator and BLM numbers) to get them to run
>> right, until now.
>>
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