Re: [DML] Re: Megasquirt Fuel Maps

[Nick Kemp <nkemp@xxxxxxxx>]

I suspect the difference we are talking about is similar to Feasible" 
versus "Optimal". Even though a carburator has been set up, tuned, to 
one engine does not mean that it will run equally well on another. In 
fact it could run better or worse on the customer's engine. The same is 
true for the MS. The map from one engine (with identical mechanical 
configuration) will likely run on other engines but tuning it may help 
it run better (or not). The tuning compensates for the condition of the 
engine, sensors and components.

I had a neighbor that was into Ferrari cars and was a strong advocate 
that points could run as well as electronic ignition. For the most part 
he was right given one important caveat. That is that you had to keep 
them tuned for wear and environmental conditions. And grandma is not 
going to be tuning her points each day to compensate for wear and weather.

Electronic engine controls (including EFI) automates the tuning process 
(micro tuning process) to adjust for temperature, air pressure, fuel 
quality, ping, throttle position, engine characteristics, etc. Can a 
well tuned carb work well? Absolutely. In all & varying conditions 
(weather, altitude, wear, usage) without customer involvement? This is 
where EFI & Electronic ignition shine since they can compensate for more 
environmental and mechanical variables.

Nick

content22207 wrote , ----On 4/20/2012 1:48 PM ---------------------------:
>
> The challenge is making a turn key EFI conversion that an owner can 
> simply bolt on then start using -- is such a "kit" realistically possible?
>
> In all fairness, I set up each carburetor while test driving its 
> manifold (for vacuum tightness) on my own car. Some things, like 
> venturi and jet sizes, are fixed, but I do set the choke and idle 
> mixture screws. That allows the end user to simply bolt it on out of 
> the box then start driving it. Unfortunately there seems to be no way 
> to do the same with EFI.
>
> David made the comment that one user can set up a fuel map, then other 
> users just download it and start using it. That has not been Owen's 
> experience on virtually identical installations. I think Megasquirt at 
> least will require a lot more setup on end users' part than simply 
> bolting fuel rails on. Hopefully anyone contemplating EFI realizes 
> that -- it is much more than a Saturday afternoon project.
>
> Bill Robertson
> #5939
>
> --- In dmcnews@xxxxxxxxxxxxxxx <mailto:dmcnews%40yahoogroups.com>, 
> "Matthew" <drivestainless@...> wrote:
> >
> > Hi Richard, and everyone else,
> >
> > Bill saw my car yesterday, which has a 3.0L PRV with a B280F throttle
> > body, running Megasquirt II and the Ford EDIS ignition.
> >
> > Bill mentioned to me during his visit that K-Jet owners have idle
> > oscillation. What I explained to him was that Megasquirt users can have
> > idle oscillation as well. One reason being a relatively "large"
> > discrepancy between adjacent cells in the fuel or spark tables at idle
> > which causes the mixture, and thus the idle, to oscillate. Yes, the
> > system does interpolate between cells, usually several at a time, but
> > having just one value out of range can create an oscillation.
> > Ironically an idle valve can sometimes make the problem worse as it
> > attempts to counter the oscillation. Using the tuning software, I can
> > force my engine to oscillate the idle and post a video as an academic
> > gesture if there is disagreement over this.
> >
> > Someone mentioned about EFI using a closed loop system with feedback
> > from the oxygen sensor. I believe by default, in Megasquirt, the oxygen
> > sensor doesn't become active until > 1500 RPMs, so this is a moot point
> > with respect to idle. There are many other reasons for idle oscillation
> > which a Google search will quickly reveal (megasquirt idle
> > hunting/oscillation).
> >
> > I did not mean to imply that idle oscillation was commonplace among EFI
> > systems, but wanted to show Bill that the mere fact that you're using
> > EFI doesn't preclude having some of the same problems you would have on
> > an antiquated fuel delivery system.
> >
> > I do think that a universal kit could be made, but providing support for
> > it would be practically impossible. Additionally, some owners may not
> > be willing to make the drastic changes to the car which provide (in my
> > opinion) the best cosmetic and practical results (i.e., removing the
> > fuel accumulator, cutting and splicing wire harnesses, modifying
> > brackets to hold new components, removing and adding new circuits to the
> > stock fuse box, etc).
> >
> > I did many of these things because I did not want the car to look like a
> > DeLorean where EFI was added - I wanted it to look like a stock EFI 3.0L
> > DeLorean. Even Bill shares this view in part of his carbureted car
> > because he's added updated vacuum routing diagrams, removed unnecessary
> > wiring, and sealed off holes in the fiberglass where components no
> > longer are in place.
> >
> > Matt
> > #1604
> >
> >
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
> 



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