Randy, thanks for the kind words. When it comes to fuel injection, I
started out with pure mechanical systems, like the Rochester system on
early Corvettes, and Volkswagen Bosch as used on Rabbits, Audi Foxes,
Squareback and Fastback VW, and Aftermarket systems like Stu Hilborn made.
Then, EPA stuck its nose in, and electricity slowly crept in to
control mechanical systems. An improvement, but just a baby step.
Evolution being what it is, computers made their debut. No longer baby
steps, but "a giant leap for mankind".
My understanding of computers at that time was Commodore 64's. You
remember them, Great harmony, bell bottom pants, boogie shoes. I learned
radio theory around vacuum tubes, not transistors.
Then came GM CCC. Stood for computer command control. Flashed out
trouble codes on the dash display on the heater/a/c controls. Had to push
the "on" and "warmer" buttons and hold them in for 5 seconds. Then count
the flashes and read the manual to interpret the stored codes. Simply
Amazin'. That system morphed into the current 747 GM computer models. Cost
GM BILLIONS OF 1985 DOLLARS to develop. They got it right the first time.
That's where I started out.
Jim Hupy
> > Jim, that is a good point. I always forget about the 403. a EFI that
> was originally on a 454 engine, a person would think it pretty close to a
> > 455. but a 403 is different.
>
> Not a tremendous amount of difference between a 455 and 403. There is
> enough room for the ECM to learn the difference so a 455 program will run a
> 403. That being said, there are a few things that can be done to make the
> 403 run much better. Primary difference is in fueling. The 403 does not need
> quite as much fuel. When I set up a base 455 and 403, there is a parameter
> that sets the starting point for fuel. It defines the base pulse width,
> e.g., how long the injector stays open on each pulse cycle. A bunch of
> other stuff is added/subtracted from that base to get the final injector
> open
> time. It is not important to know what these numbers mean for this
> discussion, but for the 455 I start with a number of 148 and for the 403
> the number
> is 119. Just looking at the relative difference, you can see that the 455
> needs to keep the injectors open longer than a 403. The other area where I
> make changes for the 403 is for spark advance. The 403 can tolerate and is
> happier with more spark advance than the 455. So, will both run off the
> same program - yes, because the ECM can compensate (learn) but would I
> advocate the same program for both - absolutely not.
>
> Jim says you need more smarts to run a EFI system. I don't agree with
> that. It is a different set of skills but no more or less difficult than
> learning a carb. If you have grown up messing with carbs all your life,
> then you will always think that is a piece of cake. Same can be said of EFI.
> For me, I do not have the skill set to understand and tinker with a carb.
> I can mess one up quicker than you can say carburetor. But I can work on an
> EFI system. Just different skill sets. I've known jimH for quite a while
> now and I can definitely say he knows far more about our engines than I will
> ever know. But we all have skill set that we understand better. That is
> the value of our community. We can each lean on the other for information in
> skill set areas we are not as versed in.
>
> Oh, Jon, I think you meant to say the EBL is an optional upgrade. Yes, it
> is an optional upgrade. The base GM system will run in our environment very
> well. The problem is associated more with the starting chip for our
> engines and doing some fine tuning when and if that is needed. The OEM efi
> system
> is difficult to determine what is needed (data is not easily retrieved)
> and the process to burn a new chip is cumbersome. The EBL upgrade, in
> addition
> to a noticeable difference in how the engine runs, provides data easily
> and allows changes to the programs quickly. In addition, some of the fine
> tuning can be accomplished automatically with it's ability to update the
> Volumetric Efficiency tables. So, with the OEM designed self learning as
> well
> as the enhanced learning provided by the EBL, you can quickly get the
> system fine tuned. The EBL upgrade makes the EFI system act like a modern
> day
> factory system with avg mpg, instantaneous mpg, moles traveled as well as
> gallons used. Having said all of that, many have installed the EFI system
> (both kits and DIY), loaded the default program and run great without ever
> touching the system again. I probably have been running my 403 with the EBL
> for nearly six years without touching the system. And I "touch" the system
> not because I have to, but because I want to see what a specific change
> might do. I know several who have never touched the system since it was
> installed.
>
> --
> Randy & Margie
> '77 Eleganza II '403'
> Battlefield, MO
>
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