I was about to clarify that myself as a result of further reading this
evening...
On Thu, 6 Aug 1998, Joe Grubbs wrote:
> Jim Lill wrote:
> >
> > It is very significant that the EZ200K ignition ECU is tied to the
> > L-Jetronic and controls injection duration. This suggests that a ROM
> > change in the EZK can control the FI in addition to the timing.
> >
>
> Jim,
>
> According to 505 Turbo Electrical Service Manual:
>
> "...The basic amount of time for the injectors to operate
> is determined by the signals that the INJECTION ECU receives
> from the altitude sensor, the air flow sensor, the microswitch,
> and the engine RPM signal from the IGNITION ECU and the Start
> signal from the ignition switch. This calculated Basic Injection
> Duration signal is sent to the IGNITION ECU.
>
> The Basic Injection Duration signal is modified by the following
> signals: (1) the battery voltage; (2) the exhaust oxygen content
> measured by the lambda sensor; (3) the engine temperature sensor;
> and (4) the Full Load Data signal from the IGNITION ECU. The INJECTION
> ECU provides a ground for the injectors for a period to last
> for the modified Basic Injection Duration time..."
>
> ---
>
> In other words--the IGNITION ECU does not affect injector duration,
> in fact, injector duration affects the ignition according to the
> above paragraphs. And that makes sense--injector duration decisions
> are made solely by the INJECTION ECU, as they are on any Lx-Jet
> system.
>
> BTW, the "full load data signal" generated by the IGNITION ECU
> and sent to the INJECTION ECU combined with the closed throttle
> microswitch takes the place of the integrated throttle switch
> found on most other Lx-Jet applications. The word "data" is
> confusing because it is simply an on-off signal. The ignition
> ECU decides when the engine is under full-load and tells the
> injection ECU to go extra-rich.
>
> Joe
>