<VV> RE: Fuel injection (long)

[Craig Nicol]

Cash said:
One  thing I did find out today was that If I were to buy a new ECU  
from  an parts store, and they do sell them, it would not work until I   
installed it and then took the car (get it towed) to a chevy dealer   
to 'flash' the ECU. Apparently they come blank from the  manufacturer.  
The charge for flashing the ECU I assume would be over  $100.00. I  
can't imagine that it would be any less. If I'm going to  put that  
much money into the ECU, I'll be buying a MegaSquirt unit.  

Cash also said:
The other option if I were to use a Cavalier ECU would be to purchase it
from a salvage yard. That's a possibility. I went to uneedapart.com. This is
a nationwide network of salvage yards. They will give you a price including
shipping. I'm getting prices from $50 bucks up to $100 for the Z24 unit
which was the 2.4 liter engine. I believe. There is of course no way to test
and make sure the unit  is good until it is installed. I'm leaning towards
the MegaSquirt unit.

Joel Said
All this talk about the Cavalier/Fiero ECUs kinda leaves me scratching my
head.  Five years ago those might have been viable choices, but not today,
in my eyes.  MegaSquirt has the advantage (a HUGE one) of having mega
support to go along with it.  For a DIY'er on the budget, there is just no
other better option. www.msefi.com

Regards,
Joel

Scotty Said:
Why not use the Fiero system if you can find one.  Craig Nicol has  them on 
his rigs and appears very satisfied with it.
 
Craig Replies:
The Megasqirt unit appears to be very good, with lots of options.  My
neighbor is putting one into a turbocharged 300-6 powered 50 GMC cabover. He
relies on me for many things and I expect to be on point for its
programming. (Megasquirt supplies a program that will get it running, but
from there YOYO (with lots of advice available online and directly). I think
his Megasquirt ECM (Assembled) was in the $300 range not counting sensors.
If you are willing to learn all about how fuel maps work and have a laptop
with a serial port you can probably get the map close in a day. One of the
odd things about Megasquirt is that whenever there's a magazine shootout of
the various aftermarket ECU options, Megasquirt is never included.  Perhaps
their advertising budget (none AFIK) doesn't put them on the magazine's
radar screen.  

Taking a fresh ECU to the dealer to be flashed is not a viable option. What
program would you have them flash in?  They usually go by VIN; what VIN
would you give them? The ecu must be in a car that's similar to the source
vehicle to program correctly, and all kinds of systems (that Corvairs don't
have) would throw all sorts of codes. Also, isn't the Cavalier Z24 a
4-cylinder engine?

Pre-flash ecus (with programming chips, about '93 and older) are much more
viable.  You talk to a chip vendor (Like TPIS) and they'll make you a chip
that's close.  Once installed in your ECM and running, you tell them what
the numbers are (like LTFT and STFT and so on) in various modes and they'll
make a second chip that's really close - the ECU dials it in from there.

Support (like Megasquirt's or Street & Performance) is great, but whenever
you go down this road, it still boils down to you.  You ask intelligent (or
dumb) questions, you learn, you change, and you evaluate whether or not it
worked. It might take two questions or two hundred depending on where you're
your starting from.  When I started on my Fiero-based car, I first bought
half a dozen GM training manuals and learned all I could about how EFI
worked. After a bunch of reading, it finally "clicked" and I understood what
was going on in those tiny little brains (the car's not mine).  I'd suggest
that anyone who wants to do an EFI conversion learn ALL about them before
buying anything.

As for the Fiero no longer being viable... SAE looked at all the available
EFI systems in the early '90s in a effort to develop a standard EFI
interface.  They picked the GM system and beginning in '96, all vehicles had
to use GM parts nomenclature, signal names, and interface - this GM based
standard is known as OBD-II.  EVERY mechanic out there knows the GM system
and it's foibles because it's the basis for OBD-II. Also, every aftermarket
system that I've seen uses GM sensors.  It's pretty hard to beat a GM-based
system that's basically "plug and play".  OTOH, if you are dealing with
something that's radically different than a stock 110 or 140, you probably
would want to consider something else that has a MAF or wide-band O2
capability - GM OE or Megasquirt.
Craig