9-5 Sport Wagon (9600) V6-3.0L Turbo (B308) (2003)
/v6-3.0l_turbo_(b308)/Page-1121002.png)
The Trionic T7 has no camshaft position sensor as normally required for sequential knock control and fuel injection.
As the firing order of the engine is 1-2-3-4-5-6 while cylinders 1-3-5 are in bank 1 and cylinders 2-4-6 in bank 2, combustion will take place alternately
in the two banks.
On starting, the control module does not know which of cylinder 1 and 4 is in the compression position, so ignition takes place in both cylinder 1 and
cylinder 4 simultaneously. Ignition takes place in cylinders 2 and 5, and 3 and 6 respectively in the same way.
The control module determines whether combustion is taking place in bank 1 or bank 2 in the following way:
One pole of the secondary windings of the 3 ignition coils is normally connected to the relevant spark plug. The other pole is not grounded direct but
connected to 80 V. This means that a voltage of 80 V is always present across the spark plug gap except just as the spark is produced.
When combustion takes place, the temperature in the combustion chamber is very high. The gases are ionized and begin to conduct current. This means
that current passes between the spark plug electrodes without producing a spark.
As the circuit is completed between the spark plug electrodes, the current (80 V) flowing across the gap drops sharply. The voltage drop will be
proportional to the pressure and temperature in the combustion chamber.
A detector measures the voltage drop over the three spark electrodes in each discharge module. If combustion is taking place in cylinders 1-3-5 (bank 1),
the discharge module sends a B+ pulse to control module pin 53. In the same way, the discharge module for bank 2 sends a B+ pulse to control module
pin 6 if combustion is taking place in cylinders 2-4-6.
If cylinders No. 1 and No. 4 are triggered and a B+ pulse is received on control module pin 53 at the same time, the control module knows that cylinder
No. 1 has fired.
As soon as combustion signals are received on control module pins 53 and 6, both ignition and fuel injection are synchronized to the engine firing order.
