Description

SYSTEM SCHEMATIC - CALIFORNIA EMISSION





SYSTEM SCHEMATIC - EXCEPT CALIFORNIA EMISSION

The SFI (Sequential Multiport Fuel Injection) system is composed of 3 basic sub-systems: Fuel, Air Induction and Electronic Control Systems.

FUEL SYSTEM:
Fuel is supplied under constant pressure to the SF1 injectors by an electric fuel pump. The injectors inject a metered quantity of fuel into the intake port in accordance with signals from the ECM (Engine Control Module).

AIR INDUCTION SYSTEM:
The air induction system provides sufficient air for engine operation.

ELECTRONIC CONTROL SYSTEM:
The 2JZ-GE engine is equipped with Total Computer Controlled System which centrally controls the SF1, ESA, IAC diagnosis systems etc. by means of an ECM -formerly SF1 computer employing a microcomputer. The ECM controls the following functions:
1. Sequential Multiport Fuel Injection (SFI):
- The ECM receives signals from various sensors indicating changing engine operating conditions such as:
- Intake air volume.
- Intake air temperature (IAT).
- Engine coolant temperature (ECT).
- Engine speed (RPM).
- Acceleration/deceleration.
- Exhaust oxygen content etc.
The signals are utilized by the ECM to determine the injection duration necessary for an optimum air-fuel ratio.
2. Electronic Spark Advance (ESA):
The ECM is programmed with data for optimum ignition timing under all operating conditions. Using data provided by sensors which monitor various engine functions (RPM, ECT, etc.), the ECM triggers the spark at precisely the right instant.
3. Idle Air Control (IAC):
The ECM is programmed with target idling speed values to respond to different engine conditions (ECT, air conditioning (A/C) ON/OFF, etc.). Sensors transmit signals to the ECM which controls the flow of air through the throttle valve bypass and adjust idle speed to the target value.
4. Diagnosis Function:
The ECM detects any malfunctions and abnormalties in the sensor network and lights a malfunction indicator lamp (MIL) in the combination meter. At the same time, trouble is identified and a diagnostic trouble
code (DTC) is recorded by the ECM. The DTC can be read by the number of blinks of the MIL when terminals TE1 and E1 are connected. The DTC are referred to in the Engine Troubleshooting.
5. Self-Correction Function:
If any sensor malfunctions, an average value recorded in the back-up circuit is substituted to make driving possible.
If danger is predicted, the engine is stopped and the MIL will light up.
6. Fail-Safe Function:
In the event of the sensor malfunction, a back-up circuit will take over to provide minimal driveablity, and the MIL will illuminate.