2003 HONDA CIVIC Intake manifold

Fuel and Emissions Systems
System Descriptions (cont'd)
ECM Data (cont'd)
w
DataDescriptionOpera'ting ValueFreeze Data
Fuel System
Status
Fuel system status is indicated as "open" or "closed".
Closed: Based on the A,/F Sensor output, the ECM
determines the airlfuel ratio and controls the amount of
injected fuel.
Open: lgnoring Ay'F Sensor output, the ECM refers to
signals from the throttle position {TP), manifold absolute
pressure (MAP), intake air temperature (lAT), barometric
pressure (BARO), and engine coolant temperature (ECT))
sensors to control the amount of iniected fuel.
At idle speed: closedYES
Short Term
FuelTrim
The airlfuel ratio correction coefficient for correcting the
amount of injected fuel when the fuel system status
is "closed." When the ratio is leaner than the
sloichiometric ratio, the ECM increases short term fuel
trim gradually, and the amount of iniected fuel increases.
The airlfuel ratio gradually gets richer, causing a lower
oxygen content in the exhaust gas. Consequently, the
short term fuel trim is lowered, and the ECM reduces the
amount of injected fuel.
This cvcle keeps the airlfuel ratio close to the
stoichiometric ratio when in closed loop status.
o.7 1.5YES
Long Term
Fuel Trim
Long term fuel trim is computed from short term fuel trim
and indicates changes occurring in the fuel supply system
over a long period.
lf long term fuel trlm is higher than 1.00, the amounl of
injected fuel must be increased. lf it is lower than 1.00, the
amount of injected fuel must be reduced.
0.8 1.2YES
Intake Air
Temperature
{IAT)
The IAT sensor converts intake air temperature into
voltage and signals the ECM. When intake air
temperature is low, the internal resistance ofthe sensor
increases, and the voltage signal is higher.
With cold engine:
Same as ambient
temperature and ECT
YES
Throttle
Position
Based on the accelerator pedal position, the opening
anole of the throttle valve is indicated.
At idle speed:
about 10 %
YES
lgnition
Timing
lgnition timing is the ignition advance angle set by the
ECM. The ECM matches ignition timing to driving
conditions.
At idle speed: 8" t 5"
|' tuL wnen rne >L)
service signal line is
jumped with the Honda
PGM Tester
NO
Calculated
Load Value
(cLV)
cLV is the enoine load calculated from IMAP data.At idle speed:
12 34%
At 2.500 rpm with no
toao:'t4- 34%
YES
11-14
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ra

Vacuum Hose Routing
I
O AIR FUEL RATIO IA/F) SENSOR {SENSOR 1}O SECONDARY HEATED OXYGEN SENSORISECONDARY HO2S} {SENSOR 2}
O MANIFOLD ABSOLUTE PRESSURE (MAPI SENSORO ENGINE COOLANT TEMPERATURE {ECT) SENSORO INTAKE AIR TEMPERATURE (IAT) SENSORO CRANKSHAFT POSITION (CKP) SENSORO KNOCK SENSORO CAMSHAFT POSITION (CMPI SENSOR BITOP DEAD CENTER ITDC) SENSOR)
O CAMSHAFT POSITION ICMPI SENSOR A@ IDLE AIR CONTROL (IACI VALVEO THRONLE BODY.O INJECTOR@ FUEL PULSATION OAMPER[I FUEL FILTER@ FUEL PRESSURE REGULATOR@ FUEL PUMP@ FUEL TANK
@ RESONATOR(9 AIR CLEANER@ POSITIVE CRANKCASE VENTILATION {PCVI VALVE@ THREE WAY CATALYTIC CONVERTER@ EVAPORATIVE EMISSION {EVAPI CANISTER@ EVAPORATIVE EMISSION {EVAP) CANISTERPURGE VALVE{} EVAPORATIVE EMISSION (EVAPI CANISTERVENT SHUT VALVE{' EVAPORATIVE EMISSION {EVAP) TWO WAY VALVE@ EVAPORATIVE EMISSION IEVAPI BYPASSSOLENOID VALVE@ FUEL TANK PRESSURE (FTP) SENSOR@ EVAPORATIVE EMISSION IEVAP} VALVE@ FUEL TANK VAPOR CONTROL VALVE60) FUEL TANK VAPOR RECIRCULATION VALVEO INTAKE AIR BYPASS CONTROL THERMAL VALVE
(cont'd)
11-25

lgnition Timing Control
The ECM contains the memory for basic ignition timing
at various engine speeds and manifold absolute
pressure. lt also adjusts the timing according to engine
coolant temperature.
Iniector Timing and Duration
The ECM contains the memory for basic discharge
duration at various engine speeds and manifold
pressures. The basic discharge duration, after being
read out from the memory, is further modified by
signals sent from various sensors to obtain the final
discharge duration.
By monitoring long term fuel trim, the ECM detects long
term malfunctions in the fuel system and sets a
Diagnostic Trouble Code {DTC).
Intake Air Temperature (lAT) Sensor
The IAT sensor is a temperature dependent resistor
{thermistor). The resistance of the thermistor decreases
as the intake air temDerature increases.
Knock Sensor
The knock control system adjusts the ignition timing to
minimize knock.
PIEZOCERAMIC
Malfunction Indicator Lamp lMlLl Indication {ln relation
to Readiness Codes)
The vehicle has certain "readiness codes" that are part
of the on-board diagnostics for the emissions systems.
lf the vehicle's baftery has been disconnected or gone
dead. if the DTCS have been cleared, or if the ECM has
been reset. these codes are set to incomplete. In some
states, part of the emissions testing is to make sure
these codes are set to comDlete. lf all of them are not
set to complete, the vehicle may fail the test and the
test cannot be finished.
To check if the readiness codes are set to complete,
turn the ignition switch ON (ll). but do not start the
engine.TheMILwill comeonforlS 20seconds. lf it
then goes off, the readiness codes are set to complete,
lf it blinks severaltimes, one or more readiness codes
are not set to comolete. To set each code, drive the
vehicle or run the engine as described in the
procedures to set them in this section (see page 1 1-46).
Manifold Absolute Pressure {MAP) Senso]
The MAP sensor converts manifold absolute pressure
into electrical signals to the ECM.
SENSOR UNIT
(cont'd)
11-27

Fuel and Emissions Systems
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{
System Descriptions (cont'd)
ldle Control System
When the engine is cold, the Ay'C compressor is on, the
transmission is in gear, the brake pedal is pressed. thepower steering load is high, or the alternator is
charging, the ECIM controls current to the ldle Air
Control (lAC) valve to maintain the correct idle speed.
Refer to the System Diagram to see the functional
layout of the system.
Brake Pedal Position Switch
The brake pedal position switch signals the ECM when
the brake pedal is oressed.
Electrical Power Steering (EPS) Senser
The EPS sensor signals the ECM when the power
steering load is high.
ldle Air Control llACl Valve
To maintain the proper idle speed, the IAC valve
changes the amount of air bypassing the throttle body
in response to an electrical signal from the ECM.
From AIR To INTAKECLEANER MANIFOLD
IAC VALVE
11-32
Fuel Supply System
Fuel Cut-off Control
During deceleration with the throttle valve closed,
current to the injectors is cut off to improve fuel
economy at engine speeds over 1,030 rpm. Fuel cut-off
action also occurs when engine speed exceeds
6,900 rpm, regardless of the position of the throttle
valve, to protect the engine from over-rewing. When
the vehicle is stopped. the ECM cuts the fuel at engine
speeds over 6,500 rpm.
Fuel Pump Control
When the ignition is turned on, the ECM grounds the
PGM-Fl main relay which feeds current to the fuel pump
for 2 seconds to pressurize the fuel system, With the
engine running. the ECM grounds the PGM-Fl main
relay and feeds current to the fuel pump. When the
engine is not running and the ignition is on, the ECI\4
cuts ground to the PGM-Fl main relay which cuts
current to the fuel pump.
PGM-FI Main Relay 1 and 2
The PGM-Fl main relay consists of two separate relays.
Relay 1 is energized whenever the ignition switch is ON(ll) to supply battery voltage to the ECM power to the
injectors, and power for relay, Relay 2 is energized to
supply power to the fuel pump for 2 seconds when the
ignition switch is turned ON (ll), and when the engine is
runnrng.

Fuel and Emissions Systems
System Descriptions (cont'dl
ldle Control System Diagram
The idle speed of the engine is controlled by the ldle Air Control (lAC) varve:
'Aftertheenginestarts,theIACvalveopensforacertainamountoftime.Theamountofairisincreasedtoraisethe
idle sDeed.. When the engine coolant temperature is low, the IAC valve is opened to obtain the proper fast idle speed. Theamount of bypassed air is controlled in relation to engine coolant temperature.
INTAKE MANIFOLDIAC VALVEAKE AIR DUCT
CLEANER
\
BLK/REO
YEL/BLK ---< FromPGM.FIMAINRELAY
THROTTLE AODY
Intake Air System Diagram
This system supplies air for engine needs. A resonator in the intake air
drawn into the svstem.
VARIOUSSENSOnS
pipe provides additional silencing as air is
THROTTLE AODYVARIOUSSENSORS
BLK
BLK
I
11-36
{

Evaporative Emission (EVAPI Control Diagram
The EVAP controls minimize the amount of fuel vapor escaping to the atmosphere. Vapor from the fuel tanK rstemporarily stored in the EVAP canister until it can be purged from the canister into the engine and burneo.
. The EVAP canister is purged by drawing fresh air through it and into a port on the intake manifold.The purging vacuum is controlled by the EVAP canister purge valve, which operates whenever engine cootanttemperature is above 149'F (65"C).
'WhenvaporpressureinthefueltankishigherthanthesetvalueoftheEVAPtwowayvalve,thevalveopensano
regulates the flow of fuel vapor to the EVAP canister.'Duringrefueling,thefueltankvaporcontrol valve opens with the pressure in the fuel tank, and feeds the fuel vaDorto the EVAP canister.
FUEL TANKVAPORRECIRCULATIONVALVE
FUEL TANKVAPORSIGNAL TUBE
BLU/RED
FUEL FILL CAP
BLK
+EVAPCANISTER
FUEL TANKVENT SHUTVALVE
BLK/YELFrom-- FUEL TANKVAPORRECIRCULATIONTUBE
EVAPCANISTER
EVAP TWO WAYVALVE
(cont'd)
11-37

PGM-FI System
Component Location Index
CAMSHAFT POS]TION {CMP) SENSOR B(TOP DEAD CENTER (TDC}SENSORITroubleshootina. oaoe 1 1-95Replacement, p;ge 1-1.1 14
ELECTRICAL LOADDETECTOR {ELDITroubleshooting,page 1'l -92
INTAKE AIR TEMPERATURE{IATI SENSORTroubleshooting,page 'l'l-55
Replacement, page 11-'l 15
f- \
rl
KNOCK SENSORTroubleshooting, page 1 1-77Beplacement, page 11 115
ENGINE COOLANT TEMPERATURE(ECTI SENSORTroubleshooting, page 1 1-57Replacement, page 11 114
MANIFOLD ABSOLUTE PRESSURE(MAP) SENSORTroubleshooting, page 1 1-52
THROTTLE POSITIONITP} SENSORTroubleshooting, page 11-60CRANKSHAFT POSITIONICKPISENSORTroubleshooting, page'l 1-78Beplacement, page 1 1-'l 16
AIR FUEL RATIO {A/F)SENSOR ISENSOR 1}Trorrbleshooting, page 1 1-84Replacement, page 11- 1 13
{cont'd)
ii'- r'1
.I11 ---:,I''.!,i(..,.?:fir-J-
.....,..:--.
11-49

PGM-FI System
Injector Replacement (cont'd)
7. Coatthenewo-rings(A)withcleanengineoll,andinserttheinjectors(B) intothefuel rail (C).
8, lnstall the injector clip {D).
9. Coat the injector o-rings (E)with clean engine oil.
10. Installthe injectors intothefuel rail, then install the fuel rail intotheintakemanifold(G).
1 '1. Install the fuel rail mounting nuts, ground cable. and bracket.
12. Connect the connectors to the injectors.
13. Connect the quick-connect fittings.
14. Turnthe ignition switch ON (ll), butdo notoperatethe starter. Afterthefuel pump runs for about 2 seconds, the
fuel pressure in the fuel line rises. Repeat this two or three times. then check for fuel leakage.
\
11-112