2003 HONDA CIVIC injector

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.

Intake Air System
Refer to the System Diagram to see the functional
layout of the system.
Intake Air Bypass Control Thermal Valve
When the engine is running, the intake air bypass
control thermal valve sends air to the iniectors,
INJECTOR
Throttle Body
The throttle body is a single-barrel side draft type. lt
houses the TP senser and the IAC valve. The lower
portion of the IAC valve is heated by engine coolant
from the cylinder head.
IAC VALVE
{cont'd)
11-33

PGM-FI System
DTC Troubleshooting (cont'dl
DTC P0171: Fuel System Too Lean
DTC P0172: Fuel System Too Rich
NOTE: lf some of the DTCS listed below are stored at
the same time as DfC PO17'l and/ot PO172,
troubleshoot those DTCS first, then recheck for P0171
andlot P0112.
P0107, P0108. P1 128. P1 129: Manifold absolute
pressure (MAP) sensor
P1 162. P1 166, P 1 167: 4,,/F sensor (Sensor 1 ) heater
P0137, P0138: Secondary HO2S (Sensor 2)
P014'l: Secondary HO2S (Sensor 2) heater
P1259: VTEC system
1. Check the fuel pressure (see page 11-'145).
ls luel pressure OK?
YES Go to step 2.
NO Check these items:
. lf the pressure is too high, replace the fuel
pressure regulator (see page 11-152).1. lf the pressure istoo low.checkthefuel pump,
the fuel feed pipe, the fuel filter, and replace the
fuel pressure regulator (see page 11-152).I
2. Start the engine. Hold the engine at 3,000 rpm with
no load (in neutral) until the radiator fan comes on.
11-70
3. Turn the ignition switch OFF.
4. With a vacuum pump, apply vacuum to the
evaporative emission (EVAP) canister purge valve
(A) from the evaporative emission (EVAP) canister
side.
' A973AX-041-XXXXX
Does it hold vacuum?
YES-Check the engine valve clearances and adjust
if necessary, lf the valve clearances are OK, replace
the injectors (see page 1 1-1 1 1).1
NO-Replace the EVAP canister purge valve.l

PGM-FI System
IDTC Troubleshooting (cont'dl
DTC P0301: No. 1 Cylinder Misfire
DTC P0302: No. 2 Cylinder Misfire
DTC P0303: No. 3 Cylinder Misfire
DTC P0304: No. 4 Cylinder Misfire
1. After checking and recording the freeze data, reset
the ECM (see page 1 1-4). lf there is no freeze data of
the misfire, just clear the DTC.
2. Start the engine, and listen for a clicking sound
from the injector at the problem cylinder.
Does the injector click?
YES-Go to step 3.
NO-Go to step 30.
3. Turn the ignition switch OFF.
4. Exchange the ignition coil from the problem
cylinder with one from another cylinder,
5. Test-drive the vehicle for several minutes in the
range of the freeze data or under va rious
conditions if there was no freeze data.
6. Check for a DTC or a Temporary DTC with the scan
root.
ls DTC or Tempotaty DTC P0301, P0302, P0303
or P0304 ind icated?
YES Go to step 7.
NO Intermittent misfire due to poor contact at the
ignition coil connectors {no misfire at this time).
Make sure the coil connections are secure.l
11-72
8.
9.
1.
11.
Determine which cylinder(s) had the misfire.
Does the misf ire occur in the cylinder where the
ignition coil was exchanged?
YES Replace the faulty ignition coil.!
NO-Go to step 8.
Turn the ignition switch OFF.
Exchange the spark plug from the problem cylinder
with one from another cylinder.
Test-drive the vehicle for several minutes in the
range of the freeze data or under various
conditions if there was no freeze data.
Check for a DTC or Temporary DTC with the scan
Tool.
ls DTC ot Tempotary DTC P0301, P0302, P0303
or P0304 ind icated?
YES Go to step 12.
NO Intermittent misfire due to spark plug fouling,
etc. (no misfire at this time).1
Determine which cylinder(s) had the misfire.
Does the misl ire occur in the cylinder where the
spark plug was exchanged?
YES Replace the faulty spark plug.l
NO Go to step 13.
Turn the ignition switch OFF.
Exchange the lnjector from the problem cylinder
with one from another cylinder.
Let the engine idle for 2 minutes.
10.
14.
t5.

16.Test-drive the vehicle for several minutes in the
range of the freeze data or under various
conditions if there was no freeze data.
Check for a DTC or a Temporary DTC with the scan
Tool.
ls DTC or Temporary DTC P0301, P0302, P0303
or P0304 indicated?
YES Go to step 18.
NO lntermittent misfire due to bad contact at the
injector connector (no misfire at this time). Make
sure the injector connection is secure. Check for
poor connections or loose terminals at the
injector.l
Determine which cylinder(s) had the misfire.
Does the misf ire occur in the cylinder where the
i njector w as exchanged ?
YES- Replace the faulty injector.I
NO-Go to step 19.
Turn the ignition switch OFF.
Disconnect the ignition coil 3P connector from the
problem cylinder.
Turn the ignition switch ON (ll).
't7 .
18.
19.
20.
22. Measure voltage between ignition coil 3P
connector terminal No. 3 and body ground.
IGNITION COIL 3P CONNECTOR
Wire side ol female terminals
ls there battery voltage?
YES-Go to step 23.
NO Repair open in the wire between the No. 1
IGN COIL (15A)fuse and the ignition coil.I
Turn the ignition switch OFF.
Check for continuity between ignition coil 3P
connector terminal No. 2 and body ground.
IGNITION COIL 3P CONNECTOR
Wire side ot female terminals
ls there continuity?
YES Go to step 25.
NO Repair open in the wire between the ignition
coiland G101.1
Disconnect ECM connector A {31P)
23.
24.
(cont'd)
11-73

32. fvleasure voltage between body ground and ECM
connector terminal (see table).
ECM CONNECTOR B (24P)
Wire side of female termrnals
ls there battery voltage?
YES-Go to step 33,
NO Go to step 41.
Turn the ignition switch OFF, and remove the
engine cover.
Disconnect the injector 2P connector from theproblem cylinder.
Measure the resistance between injector 2P
connector terminals No. 1 and No. 2.
INJECTOB 2P CONNECTOR
Terminal side of male terminals
ls there 10 Q 13A?
YES-Go to step 36.
NO Replace the injector (see page 1 1- 11 I ). t
33.
34.
35,
PROBLEM
CYLINDER
DTCEC t\4
TERMINAL
WIRE
COLOR
No. 1P0301B5BRN
No.2P0302B4RED
No.3P0303B3BLU
No.4P0304YEL
36.Exchange the injector from the problem cylinder
with one from another cylinder.
Letthe engine idle for 2 minutes.
Test-drive the vehicle for several minutes in the
range oI the lreeze data or under various
condilions if there was no freeze data.
Check for a DTC or Temporary DTC with the scan
tool.
ls DTC or Temporary DTC P0301, P0302, P0303,
or P0304 indicated?
YES Go to step 40.
NO Intermittent misfire due to injector
malfunction, etc. Make sure the injector
connections are secure. Check for poor connections
or loose terminals at the injector connector.l
Determine which cylinder{s} had the misfire.
Does the mislirc occur in the cylinder whete the
i nj ector w as exchanged ?
YES Replace the faulty injector.l
NO Update the ECM if it does not have the latest
software, or substitute a known-good ECM. then
recheck (see page 1 'l-6). lf the symptom/indication
goes away with a known-good EClvl, replace the
original ECM.I
Turn the ignition switch OFF.
Remove the engine cover.
Disconnect the injector 2P connector from the
problem cylinder.
44. Turn the ignition switch ON (ll)
37.
38.
39.
41.
42.
43.
(cont'd)
11-75

PGM-FI System
a
I
DTC Troubleshooting (cont'dl
45. Measure voltage between injector 2P connector
terminal No. 1 and body ground.
INJECTOR 2P CONNECTOR
tll-z]
,o, ,"=rrrr*, -lt-
oI
Wire side of female terminals
ls there battery voltage?
YES-Go to step 46.
NO-Repair open in the wire between the injector
and the PGM-Fl main relay l.l
Turn the ignition switch OFF.
Check for continuity between body ground and
ECM connector terminal (see table).
46.
47.
ECM CONNECTOR B {24P)
Wire side of female terminals
ls there continuity?
YES-Repair short in the wire between the ECM
and the ;njector.I
NO-Go to step 48.
PROBLEM
CYLINDER
DTCECM
TERMINAL
WIRE
COLOR
No. 1P030'1B5BRN
No.2P0302B4RED
No.3P0303B3BLU
No. 4P030482YEL
11-76
48. Connect injector 2P co nnector term inal No.2 to
body ground with a jumper wire {see table).
INJECTOR 2P CONNECTOR
Wire side of {emale terminals
49. Check for continuity between body ground and
ECM connector terminal (see table).
ECM CONNECTOR B I24P)
Wire side oJ temale terminals
ls therc continuity?
YES Replace the injector, then recheck.l
NO Repair open in the wire between the ECM and
the injector.I
tll-Z-l-]_r-l_rNJ
IJUMPER
IwrBE
PROBLEM
CYLINDER
DTCWIRE COLOR
No. 1P0301BRN
No.2P0302RED
No. 3P0303BLU
No. 4P0304YEL
PROBLEM
CYLINDER
DTCECM
TERMINAL
WIRE
COLOR
No. 1P0301B5BRN
No. 2P0302B4RED
No. 3P0303B3BLU
No. 4P030482YEL

19. Disconnect each of the components or the
connectors below, one at a time, and check for
continuity between PGM-FI main relay 1 4P
connector terminal No. 1 and body ground.
. PGfvl-Fl main relay 2. ECM connector A (31P)
. Each injector 2P connector. ldle air control (lAC)valve 3P connector. Camshaft Position (CMP) sensor B (Top dead
center (TDC) sensor) 3P connector. Crankshaft position (CKP) sensor 3P connector
PGM-FI MAIN RELAY 14P CONNECTOR
ls thete continuity?
YES Go to step 20.
NO- Replace the component that made continuity
to body ground go away when disconnected. lf the
item is the ECM, update the ECM if it does not have
the latest software. or substitute a known-good
ECM, then recheck (see page 11-6). lf the symptom/
indication goes away with a known'good ECM,
replace the original ECM.
Also replace the No. 6 ECU (ECM) (15 A) fuse,
Disconnect the connectors of all these components.
. PGM-Fl main relay 2. ECM connector A (31P)
. lnjectors. ldle air control (lAC)valve
. Camshaft Position {CMP) sensor B (Top dead
center (TDC) sensor). Crankshaft position (CKP) sensor
20.
Wire side of female terminals
22.
21. Check for continuity between PGM-FI main relay 1
4P connector termlnal No. 1 and body ground.
PGM-FI MAIN RELAY 14P CONNECTOR
ls there continuity?
YES Repair short in the wire between the PGM-Fl
main relay 1 and each item. Also replace the No. 6
ECU {ECM) (15A) fuse.l
NO-Replace the PGM-Fl main relay 1. Also replace
the No 6 ECU {ECIM) (15A) f use. I
Inspectthe No. 17 FUEL PUI\4P (15A)fuse in the
under-dash f use/relay box.
ls the tuse OK?
YES Go to step 34.
NO Go to step 23.
Remove the blown No, 17 FU EL PUMP (15A) fuse
from the under-dash fuse/relay box.
Disconnect ECfvl connector E (31P).
(conr'd)
23.
24.
Wire side of female terminals
11-99