Edelbrock TBI Conversion 101

[Ludis Langens]

Shannen Durphey wrote:
> 
> I know that early 2.8 engines are double batch
> fire, 2 banks of 3 injectors.  These systems alternate banks with each
> reference pulse, front then rear.

Nope, both banks fire at the same time.  The injectors are fired every
third (on the V6) reference pulse.  The firing duration can be multiple
reference pulses long.  The position of the motor determines which
"third" pulse is used for firing.

Take a look at the '7170 schematics on my web pages.  The '6870 uses the
same PCB/circuit (different limp home chip and different harness
connections though.)  From the schematics, you'll be able to see that
both banks must fire at the same time.  You can also see how the ECM
counts reference pulses, and how you can switch the hardware between 4,
6, and 8 cylinder engines.


As to the dual injector TBI systems - I think even they fire both
injectors at the same time (with each reference pulse.)  The engine
control chip just doesn't quite have enough features to do anything
else.  Could someone with a '7747 handy check what pins 7 & 8 of the
16023263 (or just 23263) chip connect to?  Also check where pins 12 & 13
of the 16023264 chip connect.  And also, pin 1 of the two little 8 pin
P+H controllers (probably 3640).

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/