air condition HONDA CIVIC 2003 7.G User Guide

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
\.,
ra

Fuel and Emissions Systems
System Descriptions (cont'd)
PGM-FI System
The Programmed Fuel Injection (PGM-Fl) system is a
sequential multiport fuel injection system.
Air Conditioning {A/C) Compressor Glutch Relay
When the ECfM receives a demand for cooling from the
Ay'C system, it delays the compressor from being
energized, and enriches the mixture to assure smooth
transition to the AVC mode.
Air Fuel Ratio lA/Fl Sensor
The Ay'F Sensor operates over a wide airlfuel range. The
Ay'F Sensor is installed upstream of the TWC, and sends
signals to the ECM which varies the duration of fuel
injection accordingly.
SENSORTERMINALS
HEATERTERMINALS
Barometric Pressure {BAROI Sensor
The BARO sensor is inside the ECM. lt convens
atmospheric pressure into a voltage signal that the ECM
uses to modify the basic duration of the fuel injection
discharge.
ztRcoNtaELEMENT
HEATER
11-26
\,
Camshaft Position (CMPI Sensor B (Top Dead Center(TDCI Sensor)
The CMP sensor B (TDC sensor) detects the position of
the No. 1 cylinder as a reference for sequential fuel
injection to each cylinder.
Crankshaft Position (CKPI Sensor
The CKP sensor detects crankshaft soeed and
determines ignition timing and timing for fuel injection
of each cylinder as well as detecting engine misfire.
Engine Coolant Temperature (ECT) Sensor
The ECT sensor is a temperature dependent resistor(thermistor). The resistance of the thermistor decreases
as the engine coolant temperature increases.
MAGNET
TERMINAL

wEc/wc
The i-WEC has a VTC (Variable Valve Timing Control) mechanism on the intake camshaft in addition to the usual
VTEC.
This mechanism improves fuel efficiency and reduces exhaust emissions at all Ievels of engine speed, vehicle speed.
and engine load.
The VTEC mechanism changes the valve lift and timing by using more than one cam profile.
The VTC changes the phase of the intake camshaft via oil pressure. lt changes the intake valve timing continuously.
HIGH
i
LOW <-ENGINE SPEED
Drivino ConditionVTC ControlDescriDtion
Qr Light-loadBase PositionCam angle is retarded to reduce the entry of exhaust
gas into the intake port and to achieve stable fuel
consumDtion durinq lean bu rn.
?l M ed iu m/h ig h-loadAdvance ControlCam angle is advanced for EGR effect and to reduce
this pumping loss. The intake valve is closed quickly
to help reduce the entry of airlfuel mixture into the
intake port and improve the charging effect.
€) High speedAdvance-Base PositionCam phase angle is controlled for optimum valve
timinq and maximum enoine oower.
{cont'd)
11-29

Fuel and Emissions Systems
(System Descriptions (cont'dl
VTC system. The VTC system makes continuous intake valve timing changes based on operating conditions.. Intake valve timing is optimized to allow the engine to produce maximum power.'CamangleisadvancedtoobtaintheEGReffectandreducethepumpingloss.Theintakevalveisclosedquicklyto
reduce the entry of the airlfuel mixture into the intake port and improve the charging effect.. Cam angle is reduced at idle to stabilize combustion and reduces engine speed.'lfamalfunctionoccurs,theVTCsystemcontrol is disabled and the valve timing is fixed at the fully retarded position.
MAXIMUM VTC ADVANCE 50'
i l(-4 sHoRT oVERLAP
'+-|l LoNG oVERLAP
VTEC system' The VTEC system changes the cam profile to correspond to engine speed. lt maximizes torque at low engine speedand output at high engine speed.. The low lift cam is used at low engine speeds, and the high lift cam is used at high engine speeds.
LOW SPEED VALVE TIMINGHIGH SPEED VALVE TIMING
TDC
MAXIMUM VTC ADVANCE 50'
11-30

Fuel and Emissions Systems
How to Set Readiness Codes
Malfunction lndicator Lamp (MlL) Indication
(ln relation to Readiness Codesl
The vehicle has certain "readiness codes" that are part
of the on-board diagnostics for the emissions systems.
lf the vehicle's battery 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 emission testing is to make su re these
codes are set to complete. lf all of them are not set to
complete, the vehicle may fail the emission test, or the
test cannot be finished.
To check ifthe readiness codes are complete, turn the
ignition switch ON (ll), but do not start the engine. The
MIL will come on for 15 20 seconds. lf it then goes off,
the readiness codes are complete. lf it blinks several
times, one or more readiness codes are not complete.
To set readlness codes from incomplete to complete.
do the procedure for the appropriate code.
11-46
L
Catalytic Converter Monitor and Readiness
Code
NOTE:. Do not turn the ignition switch off during the
procedure.
. All readiness codes are cleared when the battery is
disconnected or when the ECM is cleared with the
OBD ll scan tool or Honda PG lvl Tester.. Low ambient temperatures or excessive slop-and-go
traffic may increase the drive time needed to switch
the readiness code from incomplete to complete.' The readiness code will not switch to com Dlete until
all the enable criteria are met.. lf a fault in the secondary HO2S system caused the
MIL to come on. the readiness code cannot be set to
comDlete until vou correct the fault.
Enable Criteria. ECT at 158"F (70'C) or higher.. Intake air temperature (lAT) at 20"F (-7'C) or higher.. Vehicle speed is steady, and vehicle speed sensor
(VSS) reads more then 25 mph (13km/h).
Procedure
1. Connect the scan tool to the vehicle's data link \
connector (DLCi, and bring up the tool's generic \"
OBD ll mode.
Start the engine.
Test-drive the vehicle under stop-and-go conditions
with short periods of steady cruise. After about
5 miles (3 km), the readiness code should switch
from incomplete to complete.
lf the readiness code is still set to incomplete, check
for a temporary DTC. lf there is no DTC, one or
more of the enable crlteria were probably not met;
2.
3.

Evaporative Emissions (EVAP) Control
System Monitor and Readiness code
NOTE:
All readiness code are cleared when the batterV is
disconnected or when the ECM is cleared with the
OBD ll scan tool or Honda PGM Tester.
The enable criteria must be repeated if the intake air
temperature (lAT) drops lower than 36'F (20"C) from
its value at engine $an up.
Enable Criteria
At engine start up, ECT and IAT are higher than 32'F(0"C) , but lower than 95'F (35"C).
At engine start up, the ECT and IAT are within 12'F(7'C) of each other.
Procedure
1. Connect the scan tool to the vehicle's data link
connector (DLC), and bring up the tool's generic
OBD ll mode.
2. Start the engine.
3. Test-drive the vehicle under stop-and-go conditions
with short periods of steady cruise. After about
2.5 miles (1.6 km), the readiness code should
switch f rom incomplete to complete.
4. lf the readinesscode isstill setto incomplete, check
for a temporary DTC. lf there is no DTC, one or
more of the enable criteria were probably not met;
repeat the procedure.
Air Fuel Ratio (A/Fl Sensor Monitor and
Readiness Code
NOTE:. Do not turn the ignition switch off during the
orocedure.. All readiness codes are cleared when the baftery is
disconnected or when the ECM is cleared with the
OBD ll scan tool or Honda PGM Tester.
Enable Criteria
ECT at 140'F (60"C) or higher.
Procedure
1. Connect the scan toolto the vehicle's data link
connector (DLC), and bring up the tool's generic
OBD ll mode.
2. Start the engine.
3. Test-drive the vehicle under stop-and-go conditions
with short periods of steady cruise. During the
drive, decelerate (wirh the throttle fully closed) for
5 seconds. After about 3.5 miles (2.2 km). the
readiness code should switch from incomDlete to
complete.
4. lfthereadinesscodeisstill set to incomplete, check
for a temporary DTC. lfthere is no DTC, the enable
criteria was probably not meU repeat the procedure.
Air/Fuel Ratio (A/Fl Sensor Heater Monitor
Readiness Code
NOTE; All readiness codes are cleared when the battery
is disconnected or when the ECM is cleared with the
OBD ll scan tool or Honda PGM Tester,
Procedure'1. Connect the scan tool to the vehicle's data link
connector {DLC), and bring up the tool's generic
OBD ll mode.
2. Start the engine, and let it idle for 1 minute. The
readiness code should switch from incomplete to
comDlete.
3. lf the readiness code is still set to incomplete, check
for a temporary DTC. lf there is no DTC, repeat theproceoure.
(cont'd)
11-47

DTC P0300: Random Misfire and Any Combination of the Following:
DTC P0301: No. 1 Cylinder Misfire
DTC P0302: No. 2 Cvlinder Misfire
DTC P0303: No, 3 Cvlinder Misfire
DTC P0304: No. 4 Cvlinder Misfire
NOTE:. lfthe misfiring is frequent enough to trigger detection of increased emissions during two consecutive driving cycles.
the MIL will come on, and DTC P0300 (and some comlrination of P0301 through P0304) will be stored.. lf the misfiring is frequent enough to damage the catalyst, the MIL will blink whenever the misfiring occurs, and OTC
P0300 (and some combination of P0301 through P0304) will be stored. When the misfirlng stops, the MIL will remain
on.
1. Troubleshoot the following DTCs first if any of them were stored along with the random misfire DTC(s):
P0'107, P0108, P1128, P1129r N4anifold absolute pressure (MAP) sensor
P0111. P0'172t Fuel svstem
P0335. P0336: Crankshaft position (CKP) sensor
P0505: ldle control system
P1 149, Pl 162, P1 163, P1 164, P 1 165: Air fuel ratio (Ay'F) sensor
P1259: VTEC system
P1361, P1362: Camshaft position (CMP) sensor B {Top dead center (TDC) sensor)
P1519: ldle air control (lAC) valve
2. Test-drive the vehicle to verify the symptom.
3. Findthesymptom inthechart below, and dothe related procedures in the order listed until you find the cause.
SymptomProcedure(slAlso check foi:
Random misfire only
at low RPM and
under load
Check fuel pressure (see page 1 1-145).. Low compressron.. Low quality fuel.
Random misfire only
du ring acceleration
Check fuel pressure (see page 11-145).Malfunction in the
VTEC system (see page
1't-123).
Random misfire at
high RPM, under
load, or under
random conditions
Check fuel pressure (see page 11-145).Correct engine valve
clearances (see page 6-
91.
11-71

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

ldle Control System
DTC Troubleshooting
DTC P0505: ldle Control System Malfunction
NOTE: lf DTC P1519 is stored atthe same time as DTC
P0505, troubleshoot DTC P1519 first, then recheck for
DTC P0505.
1. Start the engine. Hold the engine at 3,000 rpm with
no load (in neutral) until the radiator fan comes on,
then let it idle,
2. Checkthe engine speed at idle with no,load
conditions: headlights, blower fan, rear defogger,
radiator fan, and air conditioner off.
Is the engine running at 750t50 rpm?
YES - Intermittent failure, system is OK at this
trme.I
NO lf the idle speed is less than 700 rpm, go to
step 3; if it's 800 rpm or higher, go to step 4.
3. Disconnect the idle air control {lAC) valve3P
connector.
Does the engine speed increase or fluctuate?
YES- Check the idle speed {see page 1 1-138). lf the
idle will not adjust properly, clean the passage in
the throttle body, and then adjust the idle. I
NO- Replace the IAC valve.I
4. Turn the ignition switch OFF.
5. Remove the intake air duct from the throttle body.
6. Start the engine, and let it idle.
11-130
(
7. Put your fingers on the lower pon (A) inthethrottle
oooy.
Does the engine stall?
YES Checkthe idle speed (see page 11-138). lfit's
out of specification, replace the IAC valve.l
NO With the throttle valve completely closed,
check for vacuum leaks, and repair as necessary.l

A/G Signal Circuit Troubleshooting
Turn the ignition switch ON (ll).
Momentarily connect ECM connector terminals 424
and E18 with a jumper wire several times.
1.
2.
5.
Wire side of female terminals
ls there a clicking noise I rom the NC compressor
clutch?
YES Go to step 3.
NO-Go to step 6.
Sta rt the engine.
Turn the blower switch ON.
Turn the Ay'C switch ON.
Does the NC operate?
YES-The air conditioning signal is OK.I
NO 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 €CM.l
6. Momentarily connect under-hood tuse/relay box
14P connector terminal No. 10 to body ground with
a jumper wire several times.
UNDER.HOOD FUSE/RELAY BOXI4P CONNECTOR
12356
1891011IJ14
ACC (RED)
JUMPER WIRE
Wire side of female terminals
ls there a clicking noise f rom the NC compressor
clutch?
YES- Repair open in the wire between the ECM(E'18) and the Ay'C clutch relay.l
NO- Check the A/C system for other symptoms.l
11-133