TBI with TPI ecm???

[Ludis Langens]

Bruce Plecan wrote:
> 
> > Lets assume the 2.5 L4 single injector TBI engine.
> > Further, lets assume
> > the ECM is firing the injector in middle of each intake stroke:
> 
> Well, for openers, if the injector pulse is referenced to spark, then the
> injector will be firing at the beginning of the intake valve opening (but
> immaterial, IMO).

The 2.5 TBI ECM can control when the injector fires relative to the
distributor reference signal.  It uses a small table similar to the
ignition advance tables.  The table provides an angle which is then
converted to a time delay that is programmed into the hardware.

In the particular example I just looked at, the "injection angle" is
controlled by (just) the TPS (or rather, the processed TPS value).  From
0% to 50% throttle, the injector firing is delayed by 25 degrees.  From
50% to 88%, the delay drops from 25 degrees to zero.  The 25 degree
delay (50 cam degrees) should clear most airflow to a closing intake valve.

I don't know if the dual-injector V6/V8 TBIs can have this delay.  This
feature may be lost in order to support the dual injectors.


More later...

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

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