Bob - normally I would just point you at the FAQ as this question is
answered there but there has been lots of info lately re: this subject so I
will elaborate. First here's the FAQ answers:
Q: Can MegaSquirt handle throttle-body injection?
A: Yes.
Q: Can MegaSquirt control individual port injectors?
A: Yes. There are two separate injector drivers, but high-impedance
injectors can be wired in parallel (i.e. for an 8 cylinder setup, wire four
injectors in parallel and hook to bank one, and the other four to bank
two), so any setup can be handled.
Q: Is MegaSquirt a sequential-injection controller?
A: No - it is a batch injection system. With the two banks, one can fire
simultaneously or alternate between the two banks, but there are only two
banks. Sequential injection requires separate drivers for each injector, as
well as the reference pulses to determine engine cycle.
Q: Isn't a sequential injection "better" than a batch injection setup?
A: Define "better". Many OEM systems use batch injection, even the Camaro
with the Tuned Port Intake setup uses bank injection methods. Like anything
else, one's requirements or biases determine what is better. My goal was to
replace carburetors with FI with a simple system. MegaSquirt works orders
of magnitude better than any carburetor setup, the vehicle is more
responsive, gets better gas mileage, starts right up in the cold, etc. If
one really needs a sequential injection setup, look elsewhere.
Q: Can MegaSquirt be converted to a sequential setup?
A: Yes, quite easily with additional hardware. Something for the end-user
to design - go for it!
Now - the posts as of late re:this subject concerns what is best for each
application. Some people use intake manifolds w/a common plenum and some
w/individual runners. Some need extra fuel injected under certain
conditions (boosted) and some need extra fuel dispensed in certain
locations. The hardware limitation is that there are only 2 seperate
injector-controller circuits in MegaSquirt. Since injectors can be wired
in parallel - this basically means that you can have pretty much any
combination of injectors and two seperate control circuits. The cool thing
is that the control circuits are the most generic possible. It is PWM
controlled for current and duration. This means that you could use
peak-and-hold or saturated injectors, any size, any flavor
(TBI,TPI,large,small,disc,pintle,etc) and the control circuits will let you
dial in the amount of opening current, how long to send this opening
current, etc. You can modulate the injectors any way required. I'm not
aware of ANY aftermarket EFI controller that has this capability.
The short answer is no - you won't be firing each injector on an 8-cyl
engine directly at the back of an open valve in sequence. But the experts
say that this doesn't matter when you have full control because you now
have the flexibility to give your engine exactly what IT prefers instead of
what works on EVERY ones ride. For example, one guy says that his
application which has 8 injectors aimed at the backs of the 8 intake valves
AND 2 TBI injectors mounted above the throttle blades runs much better than
any combination of 8 sequential-firing injectors by themselves due to the
better atomization. His situation was that he could never find a size for
the 8 sequential-firing injectors that would not result in too much fuel at
idle or not enough at top-end. The port + TB injection setup gave him the
flexibility he needed for his application.
Another guy is running a 4+3+2 injector setup. Full source code is
provided for everything in case you still need to go outside what the base
(relatively trivial) setup provides.
This project is meant to be an extremely cheap building block approach to
full control.
Hope this helps!
Latr,
Shane
Bob Tom wrote:
> At 11:10 AM 12/18/01 -0600, you wrote:
> >--snip-- I'll be running MegaSquirt on my '93 Dak 318, my '74
> >Challenger 360 and my '96 IndyRam 360. Not sure what ignition system
> >I'll use at first. Am thinking stock Mopar Electronic on the '74, MSD
> >on the '93, and Crane on the '96. Shane
>
> Shane
>
> Has the MegaSquirt been updated to control sequential fuel injection?
> My understanding was that it could up to bank to bank (looking at it
> for the Shelby Turbo 2.2L Charger). Thanks.
>
> Bob
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:03:42 EDT