[Diy_efi] Making a fake O2

[Bernd Felsche]

On Saturday 28 May 2005 12:31, Marcello A. Belloli wrote:
> I have been trying to figure out how to make a computer run on its
> base fuel map, and not use the O2 sensor.  I was wondering if it
> might be possible to send a signal that looks like perfect mixture
> all the time?  

First; the "base" fuel map will tend to be slightly rich to avoid
excursions into lean that can rapidly damage an engine not built for
it. Read that as a warning.

> A signal that looks like no adjustment need to be made.  You could
> put this in place of the O2, so you could see the fuel map output
> without correction.  Is this possible?  

It depends on the "computer". What it believes as requiring no
adjustment may be somewhat different to stoichiometric AFR. Some
deliberately run a touch lean at cruise, for example.

If all you want is for the computer to "see" a stoichiometric AFR
using a "normal" narrow-band sensor, then a constant-voltage source
may be sufficient. Some computers expect however to see a continuous
fluctuation between lean and rich; else they believe the O2 sensor
to be faulty. Simulating such is technically not very difficult.

Figuring out which your computer expects is another matter.

-- 
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