Electronic Control System - Toyota 22R-E Service Manual

EG1–102
The MFI system is composed of three basic subsystems: Fuel, Air Induction and Electronic
Control Systems.
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.
Each injector injects, at the same time, one half of the fuel required for ideal combustion with
each engine revolution.
AIR INDUCTION SYSTEM
The air induction system provides just the right amount of air for the engine operating condition.

ELECTRONIC CONTROL SYSTEM

The 22R–E engine is equipped with a Toyota Computer Controlled System (TCCS) which
centrally controls the MFI, ESA, A/T (4WD), 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 receives signals from various sensors indicating changing engine operating conditions such
as: Intake air volume
Intake air temperature
Coolant temperature
Engine rpm
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
various engine functions (RPM, intake air volume, 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 EG1–114,115.
4. Fail–Safe Function
In the event of a sensor malfunction, a backup circuit will take over to provide minimal drivability,
and the Malfunction Indicator Lamp will light up.
ENGINE – MFI SYSTEM