Toyota 22R-E Service Manual page 436

FUEL SYSTEM
An electric fuel pump supplies sufficient fuel, under a constant pressure, to the MFI injectors.
In accordance with signals from the ECM, these injectors inject the most appropriate quantity of
fuel for the engine condition into the intake manifold.
AIR INDUCTION SYSTEM
The air induction system provides just the right amount of air for the engine operating condition.
ELECTRONIC CONTROL SYSTEM
The 3VZ–E engine is equipped with a Toyota Computer Controlled System (TCCS) which
centrally controls the MFI, ESA, Diagnosis systems, etc. by means of an Engine Control Module
(ECM, formerly the MFI computer) employing a microcomputer. By means of the ECM, the TCCS
controls the following functions.:
1. Multiport Fuel Injection (MFI)
The ECM receives signals from various sensors indicating changing engine operating conditions
such as:
Intake air volume
Intake air temperature
Engine coolant temperature
Engine speed
Acceleration/deceleration
Exhaust oxygen content etc.
These 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, intake air volume,
engine coolant temperature, etc.), the microcomputer (ECM) triggers the spark at precisely the
right instant.
3. Diagnosis Function .
When the ECM detects malfunction or abnormalities in the sensor network, it lights the mal–
function indicator lamp in the combination meter. At the same time, the trouble is identified and
a diagnostic trouble code is recorded by the ECM. The diagnostic trouble code can be read by the
number of blinks of the malfunction indicator lamp when terminals TE1 and E1 are connected.
The diagnostic trouble codes are explained on pages EG2–17S and 177.
Fail–Safe Function
In the event of a sensor malfunction, a backup circuit will take over to provide minimal
driveability, and the malfunction indicator lamp will light up.
ENGINE – MFI SYSTEM
EG2–159