[Diy_efi] tuning question

[Tim Marsteiner]

Yes. The engine and the IAT sensor get pretty hot when
idling. It's the steepness of the curve from ~68 to
~90 that may be causing some variation. Pretty tough
to control IAT on the road.

On top of this I think I am getting some heat soak. I
have an aftermarket air kit with a thick aluminum
backing plate which bolts to the cylinder heads with
some good size aluminum standoffs and guess what, the
IAT sensor is mounted through this plate, and only
sticks out less than 1/2". I have noticed that on a
given ride over time as the engine heats up, the IAT
also goes up several degrees. This is happening at
road speeds greater then 50 mph. One would think at
these speeds with good air flow it shouldn't go up
much. I think I've got another IAT sensor. I will try
just clipping it on a better spot.

Thanks,
Tim




--- Michael Richards <michael at fastmail.ca> wrote:
> I would say that the sagem graph is conservative.
> They want it running 
> extra rich in cold weather and to run a little
> richer when the intake 
> temps are unrealistically hot. I think th motec and
> hydra lines are 
> similar enough that there won't be a measurable
> difference. Off the top 
> of my head the hydra is probably more techically
> accurate.
> 
> -Michael
> 
> > Interesting that you mention IAT.
> > 
> > I just finished a little excel graph comparing my
> > bikes factory setting for fuel correction for air
> temp
> > against a standard Motec curve and the Hydra EMS
> curve
> >
>
(http://www.mrcontrols.com/installs/nemesis/tuning.htm)
> > 
> > You can view the graph here:
> > 
> > http://superxtune.com/AirTempCorrGraph.jpg
> > 
> > My bikes curve(sagem) seems to be pretty whacked.
> > 
> > Anybody ever seen anything like this?
> > 
> > Thanks,
> > Tim
> > 
> > 
> > --- Michael Richards <michael at fastmail.ca> wrote:
> >> Some of your results will depend upon the
> accuracy
> >> of your WBO2. On my
> >> Techedge I typically see within 0.1-0.2 points of
> >> repeatability given a
> >> specific load site and provided that all the
> >> corrections are working
> >> properly. If you don't have an accurate IAT
> signal
> >> or CLT for example
> >> it could account for the variation you see. Also
> be
> >> aware that ignition
> >> advance will have an effect on the measured AFR.
> >> 
> >> -Michael
> >> 
> >>> Is +/- 5% variation within the realm of
> acceptable
> >> for
> >>> a engine of this type?
> >>> 
> >>> I have heard that the wideband O2(NTK) reading
> can
> >> be
> >>> made more accurrate by correcting for EGT. Does
> >> anyone
> >>> have an idea of what AFR correction I might
> apply
> >>> based on EGT?
> >>> 
> >>> 
> >>> Thanks,
> >>> Tim
> >>> 
> >>> 
> >>> 		
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