Subaru Impreza 2003, Service Manual

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EN(H4SO)-8
ENGINE (DIAGNOSTICS)
GENERAL DESCRIPTION
• The OBD-II diagnostics procedure is different
from the usual diagnostics procedure. When trou-
bleshooting the models with OBD-II, connect Sub-
aru Select Monitor or the OBD-II general scan tool
to the vehicle.
2. ENGINE AND EMISSION CONTROL SYS-
TEM
• The Multipoint Fuel Injection (MFI) system is a
system that supplies the optimum air-fuel mixture
to the engine for all the various operating condi-
tions through the use of the latest electronic tech-
nology.
With this system fuel, which is pressurized at a con-
stant pressure, is injected into the intake air pas-
sage of the cylinder head. The injection quantity of
fuel is controlled by an intermittent injection system
where the electro-magnetic injection valve (fuel in-
jector) opens only for a short period of time, de-
pending on the quantity of air required for one cycle
of operation. In actual operation, the injection quan-
tity is determined by the duration of an electric
pulse applied to the fuel injector and this permits
simple, yet highly precise metering of the fuel.
• Further, all the operating conditions of the engine
are converted into electric signals, and this results
in additional features of the system, such as large
improved adaptability, easier addition of compen-
sating element, etc.
The MFI system also has the following features:
• Reduced emission of harmful exhaust gases.
• Reduction in fuel consumption.
• Increased engine output.
• Superior acceleration and deceleration.
• Superior startability and warm-up perfor-
mance in cold weather since compensation is
made for coolant and intake air temperature.
3. AUTOMATIC TRANSMISSION AND
ELECTRONIC-HYDRAULIC CONTROL SYS-
TEM
The electronic-hydraulic control system consists of
various sensors and switches, the TCM and the hy-
draulic controller including solenoid valves. The
system controls the transmission proper including
shift control, lock-up control, overrunning clutch
control, line pressure control and shift timing con-
trol. It also controls the AWD transfer clutch. In oth-
er words, the system detects various operating
conditions from various input signals and sends
output signals to shift solenoids 1, 2 and low clutch
timing solenoid and 2-4 brake timing solenoid, line
pressure duty solenoid, lock-up duty solenoid,
transfer duty solenoid and 2-4 brake duty solenoid
(a total of eight solenoids).
D: PREPARATION TOOL
ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS
24082AA210 CARTRIDGE Troubleshooting for electrical systems.
22771AA030 SUBARU SELECT
MONITOR KIT
Troubleshooting for electrical systems.
• English: 22771AA030 (Without printer)
• German: 22771AA070 (Without printer)
• French: 22771AA080 (Without printer)
• Spanish: 22771AA090 (Without printer)
ST24082AA210
ST22771AA030