[Diy_efi] A/F mixture, EGT and engine damage

[Tim Marsteiner]

No, the bike is equipped from the factory with a NB
sensor. I was just stating that the first set of EGT
data I had posted was with a tune that ran closed loop
at cruise loads with this sensor. And the highest EGT
recorded was when the ECU was running closed loop with
the narrow band sensor.

I am in fact capturing wideband O2 data with the DIY
WBO2 kit using the NTK sensor. And any Afrs I was
referring to in previous posts were wideband AFRs.
Sorry for the confusion.

Thanks,
Tim


--- gary <gas- at charter.net> wrote:
> > The table I posted was running with a narrow band
> O2 sensor.
> > I am pretty sure this is the worst case EGT as
> 1663 F is the
> > highest I have ever seen on this bike.
> 
> Are you stating you are using a NB O2 sensor to do
> your tuning
> with?  *IF* that is the case, you can forget about
> obtaining
> reasonably accurate info, as far as AFR is
> concerned.  Figuring
> you are using the more common 'Nernst' cell sensor,
> whether it
> is of the single or multi wire variety, (single
> being worse) the sensor
> will be too temperature dependant/influenced, to
> depend on for
> worthwhile data.  The NB sensor is designed to be
> accurate,
> (as a glorified switch only), around .45 volts,
> which is the
> stochiometric ratio of 14.7.  The further (either
> direction) from
> 14.7, the more error prone (and unreliable) the
> sensor becomes.
> If you at all serious in regards to achieving
> accurate data to use
> for diagnosing, a WB sensor and controller is a
> necessity.
> 
> > As far as cruise I have experimented with running
> LOP 15.6:1
> > or so. I get some surging at lower speeds and some
> pretty high
> > EGTs. A/F seem to be all over the place(~14.5:1 -
> ~17:1).
> 
> Again, *IF* this is with a NB, I wouldn't give ya 3?
> for the accuracy
> of that data.  Accuracy aside, even for the use of
> comparison, as
> that sensor is too influenced by temp, I
> couldn't/wouldn't rely on it.
> :shrug:
> 
> GAS
> 
> 
> ----- Original Message ----- 
> From: "Tim Marsteiner" <tmarstei at yahoo.com>
> To: <diy_efi at diy-efi.org>
> Sent: Monday, May 16, 2005 9:50 PM
> Subject: Re: [Diy_efi] A/F mixture, EGT and engine
> damage
> 
> 
> > Yes, for this engine the 13.2:1 is a good deal
> leaner
> > than need be at wot. I have run as low as 11.5:1
> at
> > wot with good power and EGTs below 1400. That's a
> no
> > brainer.
> >
> > At cruise it gets a bit more complicated. The
> table I
> > posted was running with a narrow band O2 sensor. I
> am
> > pretty sure this is the worst case EGT as 1663 F
> is
> > the highest I have ever seen on this bike.
> >
> > I guess my question was not so much if either of
> these
> > is ok, but rather which might be causing the most
> > problems. What I am hearing is that to optimize
> engine
> > life I ought to eliminate both and as long as I
> stay
> > above 10:1 or so I should be ok in terms of wall
> wash.
> >
> > Here are the results of my fix (pretty fast
> huh!?:). I
> > attacked both issues. WOT stays below 1400 F and
> > cruise stays below 1450 F.
> >
> >
> http://www.superxtune.com/images/EGT0505Cyl2_egt.jpg
> >
> > I will be honest though I have not seen a huge
> > reduction in cylinder head temps. Perhaps 10-15 F
> > reduction. It does take longer to heat up though.
> This
> > agrees with John Deakin's article "Mixture Magic".
> >
> > http://tinyurl.com/cb287
> >
> > So I think the WOT part of the above tune is good
> > except for maybe some fine tuning on a dyno and
> maybe
> > some more ignition advance.
> >
> > As far as cruise I have experimented with running
> LOP
> > 15.6:1 or so. I get some surging at lower speeds
> and
> > some pretty high EGTs. A/F seem to be all over the
> > place(~14.5:1 - ~17:1). Probably due to the ECU
> using
> > alpha-N control or perhaps that pesky IAT heat
> soak
> > problem. I will keep working on this to see if I
> can
> > stabilize the mixture LOP and lower CHT a bit as
> Mr.
> > Deakin's results indicate.
> >
> > Thanks,
> > Tim
> 
> 
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