[Diy_efi] Re: Diy_efi Digest, Vol 3, Issue 24

[Gianmarco Rizzo BE/EAS]

Hi Nikola

nice to see u again, remember we had a discussion about starting strategies. the ECU is running much better now, but still way to go :-)

gm

> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org 
> [mailto:diy_efi-bounces at diy-efi.org]On Behalf Of Nikola Radenkovic
> Sent: Dienstag, 31. Mai 2005 14:02
> To: diy_efi at diy-efi.org
> Subject: [Diy_efi] Re: Diy_efi Digest, Vol 3, Issue 24
> 
> 
> Gianmarco,
> 
> I completely agree with your post. The only thing that you
> underestimated is the percentage of fueling alteration that
> an O2 sensor signal can introduce. You said that you have a
> fine italian turbocharged car: well if it uses Weber
> Marelli IAW management the limit for fueling alterations by
> O2 sensor is +/- 20%!
> 
> But the strategy to detect faulty sensor is usually good,
> so ECU will "know" the things went wrong with the O2 sensor
> and ignore it.
> 
> And yes, there is a way to damage the engine by
> manipulating the O2 signal. First you have to make strategy
> intelligent enough to avoid ECU to detect a faulty sensor.
> Then you should signal the lean condition to the ECU (you
> should turn it rich when the ECU is approaching 20% fueling
> decrease limit, otherwise it will recognize the O2 signal
> is bad). So ECU will enrich to compensate by max 20%. On
> long term this would cause more engine wear due to the bore
> washing extensively by excessive fuel. However, this will
> take thousands of miles to be noticed.
> 
> With regards,
> Nick
> 
> > 
> > Message: 4
> > Date: Tue, 31 May 2005 12:35:13 +0200
> > From: "Gianmarco Rizzo (BE/EAS)"
> > <gianmarco.rizzo at ericsson.com>
> > 
> > David, i am no engineer, but in my limited experience
> > with EFI's, damaging an engine just by use or misuse of a
> > O2 sensor can be achieved only by dropping the sensor in
> > the inlet manifold while the engine is running.
> > 
> > those who design EFI's and those who integrate them on
> > engines know their business. O2 sensors can only correct
> > fueling by a few % and maps are usually conservatively
> > designed, so that any sensor failure won't damage the
> > engine. i have a high performance turbocharged italian
> > sportcar, which would be the perfect candidate for your
> > theory. and i can assure you, there is NO way of damaging
> > the engine by manipulating the O2 signal.
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