Toyota 1 MZ–FE Manual page 218

EG2–218
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 SFI injectors by an electric fuel pump. The
injectors inject a metered quantity of fuel into the intake manifold 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 1 MZ–FE engine is equipped with a TOYOTA Computer Controlled System (TCCS) which
centrally controls the SFI, ESA, IAC, diagnosis systems etc. by means of ECM–formerly SFI
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 operation 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, A/C (air conditioning) ON/OFF, etc.). Sensors transmit signals to the ECM which control the
flow of air through the throttle valve bypass and adjust idle speed to the target value.
4. Diagnosis
The ECM detects any malfunctions and abnormalities in the sensor network and lights a
malfunction indicator lamp (MIL) on the combination meter. At the same time, the trouble is
identified and a diagnostic trouble code is recorded by the ECM. The diagnostic trouble codes are
referred in the Engine Troubleshooting. (See page EG2–404)
5. Fail–Safe Function
In the event of the sensor malfunctioning, a back–up circuit will take over to provide minimal
driveability, and the malfunction indicator lamp will illuminate.
1MZ–FE ENGINE – SFI SYSTEM