7747 TBI/TPI Conversion 101

[Jason Weir]

Shannen Durphey wrote:

> Maybe your confusion stems from the different types of port
> injection.  I'm sure there are variations that I don't know of, but GM
> batch fire systems fire multiple injectors at once.  During
> synchronous mode operation, one ignition reference pulse into the ecm=
> one injector pulse out.  For simplicity, think of synchronous mode as
> happening during cruise.

Thanks Shannen

here we go again.  Get out your red markers and mark any mistakes......

6 cylinder batch fired setup, 2 groups of three injectors

I understand that I have no reference pulse to tell the ECM exactly what
cylinder is firing so it will not always work out as I have showed here
are far as ignition pulses firing which injector group.

firing order 1,5,3,6,2,4..  Injectors are group (1) cylinders 1,2,3 and
group (2) cylinders 4,5,6


Ignition Ref Pulse (cylinder)	Injector Group Fires

	1				1
	5				2
	3				1
	6				2
	2				1
	4				2


is this right?  Is this what I should be aiming for? 

Assuming so:
So with 2 complete revolution of the motor to get all cylinders to fire
I end up having 6 injectors firing 3 times each. On the original TBI I
had 2 injectors firing 3 times each so as Ward had mentioned I have to
adjust fuel pressure and injector size so each injector is providing 1/3
the fuel the original TBI injector did, or get it close and work with
the VE tables.

Is it really that elementary I have 3 times as many injectors so I have
to have 1/3 the injector output per injector as compared to the original
injector? Elementary in theory but not so in implementation.

So given the firing order I used above might there be a better way to
group the injectors that the way I did?


More food for thought

Jason Weir
-- 
88 Wrangler - 157K miles and counting
258 I6, 4.0 head, Cherokee header, 2 1/2 exhaust with high flow cat &
Flowmaster
GM TBI(soon MPI hopefully), Crane 260H Cam
TJ Fender Flares
http://home.att.net/~jweir
CNC 4X4 Member - http://cnc.4x4.org/