GAS CIRCUIT MULTI POINT INJECTION

Description 1058A

1.6 16v · BIPOWER, BLUPOWER

The Marelli IAW 4GF.2M system belongs to the category of systems integrated with:

• inductive discharge digital electronic ignition
• static distribution
• sequential, phased electronic injection (1-3-4-2).

1, Engine control unit

2, Injection system relay

3, Battery

4, Ignition switch

5, Engine coolant overheating warning light

6, Injection system failure warning light

7, Signal for rev counter

8, Fiat CODE connection

9, Diagnostic equipment connection

10, Climate control connection

11, Canister solenoid valve relay feed

12, Canister solenoid valves

13, Methane canisters

14, Inertia switch

15, Lambda probe

16, Methane pressure sensor

17, Methane pressure reduction unit

18, Engine timing sensor

19, Air temperature and pressure sensor

20, Engine rpm and TDC sensor

21, Methane supply manifold with injectors

22, Injector relay feed

23, Detonation sensor

24, Radiator fan

25, Engine coolant temperature sensor

26, Radiator fan high speed relay feed

27, Radiator fan low speed relay feed

28, Ignition coils

29, Vehicle speed sensor

30, Engine idle speed actuator

31, Butterfly valve position sensor

The system operates in the same way as described for the bipower version, with the exception of the functions relating the operation of the electric fuel pump and the management of the fuel vapour recirculation which are peculiar to the petrol system.

There follows a description of the specific components for the methane injection injection: for anything not dealt with, refer to chapter 1056B.

DIAGRAM OF INPUT/OUTPUT INFORMATION FROM THE CONTROL UNIT

1, Engine control unit

2, Battery

3, Ignition switch

4, Injection system relay

5, Canister solenoid valves relay feed

6, Canister solenoid valves

7, Methane pressure reduction solenoid valve

8, Radiator fan relay feed

9, Radiator fan

10, Fiat CODE connection

11, Climate control connection

12, Methane pressure sensor

13, Lambda sensor

14, Diagnostic equipment connection

15, Injection system failure warning light

16, Engine coolant overheating warning light

17, Signal for rev counter

18, Ignition coil

19, Spark plugs

20, Injector relay feed

21, Methane injectors

22, Vehicle speed sensor

23, Engine coolant temperature sensor

24, Detonation sensor

25, Butterfly valve position sensor

26, Engine idle speed actuator

27, Air temperature and pressure sensor

28, Engine rpm and TDC sensor

29, Engine timing sensor

CONTROL UNIT PIN OUT

1, N.c.

2, N.c.

3, N.c.

4, Rev counter signal

5, N.c.

6, N.c.

7, N.c.

8, N.c.

9, Lambda sensor (negative)

10, N.c.

11, N.c.

12, N.c.

13, Fiat CODE two-way line

14, Fan high speed relay operation

15, Low relay operation

16, N.c.

17, Engine coolant overheating warning light

18, N.c.

19, N.c.

20, Lambda sensor (positive)

21, N.c.

22, N.c.

23, N.c.

24, N.c.

25, Diagnostic socket (line k)

26, Injection system failure warning light

27, Power control unit earth

28, Power control unit earth

29, Control unit supply (+12V Batt.)

30, Methane pressure sensor supply 5V

31, N.c.

32, N.c.

33, Methane pressure sensor earth

34, N.c.

35, Request to engage fan low speed

36, N.c.

37, N.c.

38, N.c.

39, N.c.

40, Fan low speed relay operation

41, Air conditioning compressor relay

42, N.c.

43, N.c.

44, Lambda sensor cable screening

45, N.c.

46, Gas pressure signal

47, Key on signal

48, Air conditioning engagement request

49, N.c.

50, Vehicle speed signal

51, N.c.

52, N.c.

53, Rpm sensor (positive)

54, Sensor earth

55, Intake air temperature signal

56, Detonation sensor (positive)

57, Stepper phase C operation

58, Stepper phase D operatoin

59, Ignition coils (cylinders 1-4)

60, Butterfly valve position sensor supply +5V

61, N.c.

62, Engine coolant temperature sensor (positive)

63, Detonation sensor cable screening

64, Stepper phase B operation

65, Stepper phase A operation

66, Ignition coils (cylinders 2-3)

67, Rpm sensor (negative)

68, Absolute pressure and timing sensor supply

69, Timing sensor signal

70, Detonation sensor (negative)

71, Injector for cylinder no. 1

72, Injector for cylinder no. 4

73, N.c.

74, N.c.

75, Pressure sensor signal

76, Butterfly valve position signal

77, Rpm sensor cables screening

78, Injector for cylinder no. 3

79, Injector for cylinder no. 2

80, N.c.

METHANE INJECTORS

Construction features

The specific methane injectors are the sonic type.

The main difference between these injectors and those which operate on petrol lies in the fact that they have a larger nozzle for the exit of the methane and they receive a considerably higher pressure (9 ± 1 bar). As a result, the quantity of methane injected only depends on the opening time of the injector (injection time) which is established by the electronic control unit.

The injectors are fixed by the methane distribution manifold, which presses them into their seats in the inlet ducts.

They are also secured to the methane distribution manifold by means of safety clips. Two rubber seals (1) and (2) ensure the sealat the inlet manifold and the methane distribution manifold.

The methane is supplied at the top (3) of the injector (top feed); the connector for the operation of the injector engages in the seat (4).

Operation

The control logic for the injectors is the sequential, phased type, in other words the four injectors are operated individually according to the engine cylinder inlet sequence, whilst the supply for each cylinder can already start when the inlet stroke has already started.

METHANE MANIFOLD

Construction features

The methane distribution manifold (1) is fixed at the top part of the intake manifold. It receives methane at low pressure from the flexible pipe (2) which acts as a connection with the pressure reduction unit and distributes it to the four injectors (3).

METHANE PRESSURE SENSOR

The pressure sensor (1) is fitted on the pressure reduction unit (2), at the high pressure line (3) intake.

Construction features

It is a capacitive type sensor (where the sensitive element is made from two gold-plated ceramic discs) which contains the signal conditioning circuit.

It receives a supply of 5V.

The measurement of the methane pressure at the high pressure line is designed to:

• indicate the quantity of methane in the canister (fuel gauge)
• provide an indication to the control unit for automatically switching the supply from methane to petrol if the methane pressure is too low (below 15 bar)

Supply: pin 30

Earth: pin 33

Signal: pin 46

PETROL/METHANE SWITCH

The system has a petrol-methane selector button which operates in the following way:

• button pressed, petrol operation
• button not pressed, methane operation, with the exception of certain particular situations (initial starting after methane supply, methane has run out, faults which require a switch to petrol).