1998 HONDA CIVIC vacuum system

3.
5.
6.
1.
Fuel Cut-off Control
. During deceleration with the throttle valve closed, current to the fuel injectors is cut off to improve fuel economy at
speeds over the following rpm:. D16Y5 engine (M/T):850 rpm. D]6Y5 engine (CVT), D'16Y8 engine (USA M/T): 920 rpm
. Dl6Y8 engine (USA A,/I), D16Y7 engine (USA A,/T);910 rpm
. D16Y8 engine (Canada M/T), D16Y7 engine (canada): 990 rpm
' D16Y8 engine (Canada M/T): 1,000 rpm
. 816A2 engine: 970 rpm
. Fuel cut-off action also takes place when engine speed exceeds 6,900 rpm (D16Y5, D16Y7 engine; D'16Y8 engine:
7,000 rpm. 816A2 engine: 8.100 rpm), regardless of the position of the throttle valve, to protect the engine from
over-rewing. With '99 Dl6Y7 engine (A,/T) and '99 D16Y8 engine (A./T), the PCM cuts the fuel at engine speeds over
5,000 rpm when the vehicle is not moving.
IVC Compressor Clutch Relay
When the ECM/PCM receives a demand for cooling from the air conditioning system, it delays the compressor from
being energized, and enriches the mixture to assure smooth transition to the A,/C mode
Evaporative Emission (EVAP) Purge Control Solenoid Valve*'
When the engine coolant temperature is above 154'F (68'C). the ECM/PCM controls the EVAP purge control solenoid
valve which controls vacuum to the EVAP purge control canister.
Evaporative Emission (EVAP) Purge Control Solenoid Valve*a
When the engine coolant temperature above 154"F (68"C), intake air temperature above 32"F (0'C) and vehicle speed
above 0 mile (0 km/h) or [Ay'C compressor clutch on and intake air temperature above 160"F (41'C)], the ECM/PCM
controls the EVAP purge control solenoid valve which controls vacuum to the EVAP purge control canister.
Exhaust Gas Recirculation (EGR) Control Solenoid Valve*?
When EGR is required for control of oxides of nitrogen (NOx) emissions. the ECM controls the EGR control solenoid
valve which supplies regulated vacuum to the EGR valve
Alternator Control
The system controls the voltage generated at the alternator in accordance with the electrical load and driving mode,
which reduces the engine load to improve the fuel economy.
ECM/PCM Fail-safe/Back-up Functions
1. Fail safe Function
When an abnormality occurs in a signal from a sensor, the ECM/PCM ignores that signal and assumes a pre-pro-
grammed value for that sensor that allows the engine to continue to run.
2. Back-uD Function
When an abnormality occurs in the ECM/PCM itself, the fuel injectors are controlled by a back-up circuit independent
of the system in order to permit minimal driving.
3. Self diagnosis Function lMalfunction Indicator Lamp (MlL)l
When an abnormality occurs in a signal from a sensor, the ECM/PCM supplies ground for the lvllL and stores the DTC
in erasable memory. When the ignition is initially turned on, the ECM/PCM supplies ground for the MIL for two sec-
onds to check the MIL bulb condition.
4. Two Trip Detection Method
To prevent false indications, the Two Trip Detection Method is used for the HO2S, fuel metering-related. idle control
system, ECT sensor, EGR system and EVAP control system self-diagnostic functions. When an abnormality occurs,
the ECM/PCM stores it in its memory. When the same abnormality recurs after the ignition switch is turned OFF and
ON 0l) again, the ECM/PCM informs the driver by lighting the MlL. However, to ease troubleshooting, this function is
cancelled when you jump the service check connector. The MIL will then blink immediately when an abnormality
occurs,
5. Two (or Three) Driving Cycle Detection Method
A "Driving Cycle" consists ot starting the engine. beginning closed loop operation, and stopping the engine. lf misfir-
ing that increases emissions is detected during two consecutive driving cycles, or TWC deterioration is detected dur-
ing three consecutive driving cycles, the ECM/PCM turns the MIL on. However, to ease troubleshooting, this function
is cancelled when you jump the service check connector. The MIL will then blink immediately when an abnormality
occurs.
(cont'd)
1 1-1 05
.1.

Manifold Absolute Pressure (MAP) Sensor ('96 Models)
The scan tool indicates Diagnostic Trouble Code (DTC) P0106: A mechanical problem (vacuum leak) in the
Manifold Absolute Pressure (MAP) Sensor system'
TheMAPsensorconvertsmanifoIdabsoIutepressureintoeiectricaIsigna|sandinpUtstheEcM/PcM'
OUTPUTVOLTAGE
(v13.5
3.0
2.5
2.0
1.5
1.0
0.5
0lin. Hgl GAUGE
- The MIL has been reported on- OTC P0106 is storod.- Or from Ptobable Cause Lisl.
Problom verificetion:1. Do the ECM/PCM Reset Pro-
cedure.2. Start the engine and keep
engine speed at 1,000 rpm for
one minute with the transmis'
sion in @ or I Position {Mff
in neutral).
ls DTC P0106 indicated?
Check tor vacuum leakage or
blockage between the MAP sen'
sor and throftle bodyCheck the MAP sensor outPut:
1. Turn the ignition switch OFF
2. Turn the ignition switch ON (ll).
3. Check the MAP with the scan
tool.ls there leakage or blockage?
Chock the MAP s€nsol output:
1. Stop the engane.2. Turn the ignition switch ON (ll).
3. Check the MAP with the scan
tool.
READING300(mm Hgl
(To page 11 116)
{cont'd)ll,(To page 11-116)
1 1-1 15

PGM-FI System
Manifold Absolute Pressure (MAPI Sensor
11-122
('99 - 00 Models except D16YS engine with M/T) (contd)
The scan tool indicates Diagnostic Trouble Code (DTC) P0108: A high voltage flow vacuum) problem in theManifold Absolute Pfessure (MAp) sensor,
MAP SENSOR 3P CONNECTOR (C111I
MAPIRED/GRNI
Wire side of female terminals
vcclIYEL/RED)
ECM/PCM CONNECTOR C (31PI
JUMPER WIRE
Wire side of female terminals
Tho MIL has boon rcDortod on.DTC ml 08 b stolod.
Problem verification:'1. Start the engine. Hold theengine at 3,000 rpm with noload (in Park or neutral) untilthe radiator fan comes on, thenlet it idle.2. Check the MAP with the scantoot,
Intormittent f.ilu.e, rystom is OXat thi! time. Chock tor poor con-n6ction3 or looso wirea at C111(MAP 3en.or) and tho ECM/PC-M.
ls 101 kPa (760 mmHg.30in.Hg) or higher indicated?
Check for an open in the MAPaon5('r:1. Turn the ignalion switch OFF.2. Disconnect the MAP sensor3P connector.3. Install a jumper wire betwesnthe MAP sensor 3P conn6ctorterminals No.3 and No.2.4. Turn the ignition switch ON {ll).5. Check the MAP with the scantool.
ls 101 kPa (760 mmHg, 30in.Hg) or higher indicated?
Check fo. an opcn in wiro (SGlline):1. Removo the jumper wire.2. Measure voltage between theMAP sonsor 3P connector terminals No. 1 and No.2.
Roprir opon in tha wiJo bctwoenthc ECM/FCM (C7l rnd the MApsonln t.
ls there approx. 5 V?
Chsck for an open in tho wi.e{MAP lino}:1. Turn the ignition switch OFF.2. Install a jumper wire on theECM/PCM connectors betweenC7 and C17.3. Turn the ignition switch ON (ll).4. Check the MAP with the scantool,
Repair op€n in the wir6a bstwoontho ECM/FCM (C171 and rh6 MApscnltoa.
ls 101 kPa (760 mmHg, 30in.Hg) or higher indicated?
Substituto a known-good ECM/PCM and rechcck, It normal MAPis indiceted. r.place tho originalECM/PCM.
JUMPER WIRE
--

Fuel Supply System
System Description
The fuel supply system consists of a fuel tank, in-tank
high pressure fuel pump, PGM-FI main relay, fuelfilter,
fuel pressure regulator, fuel injectors. and fuel delivery
and return lines. This system delivers pressure-regu-
lated fuel to the fuel injectors and cuts the fuel delivery
when the engine is not running.
Fuel Pressure l'96 Modelsl
Relieving
Before disconnecting fuel pipes or hoses, release pres-
sure from the system by loosening the 6 mm service
bolt on top of the fuel filter.
. Do not smoke whil6 working on the fuel system.
Kgsp opon flames or sparks away from youl work
area.
. Be sure to relieve fuel pressure while the ignition
switch is off.
1. Write down the frequencies for the radio's preset
buttons.
2. Disconnect the battery negative cable from the bat-
tery negative terminal.
3. Remove the fuelfill cap,
4. Use a box end wrench on the 6 mm service bolt at
the fuel filter while holding the special banjo bolt
with another wrench,
5. Place a rag or shop towel over the 6 mm service bolt.
6, Slowly loosen the 6 mm service bolt one complete
rurn.
. A fuel pressure gauge can be attached at the 6 mm
service bolt hole.
. Always reDlace the washer between the service
bolt and the special banjo bolt whenever the ser-
vice bolt is loosened.
. Replace all washers whenever the bolts are
removeo.
11-230
Inspoction
1. Relieve fuel pressure.
2. Remove the service bolt on the fuel filter while hold-
ing the banjo bolt with another wrench. Attach the
special tool.
FUELPRESSUREGAUGE07406 - 00ir0(x)1
Start the engine. Measure the fuel pressure with the
engine idling and the vacuum hose of the fuel pres-
sure regulator disconnected from the fuel pressure
regulator and pinched. lf the engine will not start,
turn the ignition switch ON (ll), wait for two sec-
onds, turn it off, then back on again and read the
fuel pressure.
Pr€3sure should bo:
260 - 310 kPa (2.7 - 3.2 kgt/cmr, 38 - 46 psi)
Reconnect vacuum hose to the fuel pressure regulator,
Pressure should bo:
200 - 25O kPa l2.O - 2.5 kgf/cm', 28 - 36 psil
lf the fuel pressure is not as specified, first check the
fuel pump {see page 11-2361. lf the fuel pump is OK,
check the following:
. lf the fuel pressure is higher than specified,
inspect for;- Pinched or clogged fuel return hose or line.- Faulty fuel pressure regulator (see page 11-234).. lf the fuel pressure is lower than specified, inspect
for:- Clogged fuelfilter.- Faulty fuel pressure regulator {see page 11-234).- Fuel line leakage.
REGULATOB

tJFuel Pressure {'97 and later Models)
ReliGving
Before disconnecting tuel pipes or hoses, release pres-
sure from the system by loosening the 12 mm banjo
bolt on top of the fuel filter.
@o Do not smoke whilo working on the fuel sy3lom.
Ksgp op€n flames or sparks away tlom Your work
arga.
. Be sure to relieve fuel pressule while the ignition
swhch is off.
1. Write down the frequencies for the radio's preset
buttons,
2. Disconnect the battery negative cable from the bat-
tery negative terminal.
3. Remove the fuel fill cap.
Use a box end wrench on the 12 mm banjo bolt at
the fuel filter while holding the fuel filter with anoth-
er wrench.
Place a rag or shop towel over the 12 mm banio bolt.
Slowly loosen the 12 mm banjo bolt one complete
turn.
4.
I
12 mm BAtt OBOLT33 N.m (3.i1 kgf m,25 tbf.f0
NOTE: Replace all the washers whenever the 12
mm banio bolt is loosened or removed.
Inspaqtion
1. Relieve fuel pressure.
2. Remove the 12 mm banjo bolt from the fuel filter
while holding the fuel Jilter with another wrench
Attach the special tools.
3. Start the enginethe fuel Pressure with the
engine idling and the vacuum hose of the fuel pres-
sure regulator disconnected from the fuel pressure
regulator and pinched lfthe engine will not start, turn
the ignition switch ON {ll), wait for two seconds, turn
it off, then back on again and read the fuel pressure'
Pr$3uro ehould be:
excepi 816A2 sngine:
260 - 310 kPa {2'7 - 3.2 kgf/cm" 38 - {6 Fi}
B16A2 engine:
27O -32O kPa P.8 - 3'3 kgf/cm', '10 - 47 psi)
4. Reconnect vacuum hoso to the fuel pressure regulator'
Pre33ure 3hould be:
except B16A2 engin€:
2OO - 250 kPa {2.0 - 2'5 kgf/cm', 28 - 36 psi)
B16A2 engino:
210 - 260 kPa 121 - 2.6 ksf/cm', 30 - 37 psi)
lf the fuel pressure is not as specified, first check the
fuel pump (see page 11-236) lfthetuel pumpisoK,
check tho following:
. lf the fuel pressure is higher than specified,
inspect for:- Pinched or clogged fuel return hose or line.
- Faulty fuel pressure regulator (see page 11-
2341.
. lf the fuel pressure is lower than specified, inspect
for:- Clogged fuel filter.
- Faulty fuel pressure regulator (see page l1-
2341.- Fuel line leakage.
FUEL PRESSUREADAPTER BOLT, 12 mm
tguxt8-PD6-0101
CLAMP
REGULATOR
11-231

Fuel Supply System
Fuel Injectors
Replacement
@ Do not smoke when working on the tuel systgm, Keep gp6n flames away from your work area
'f. Relieve the fuel pressure (see pages 11-230,231J.
2. Disconnect the connectors from thefuel injectors (D16Y7 engine: Remove the air cleaner).
3. Disconnect the vacuum hoses from thefuel pressure regulator. Placeashoptowel overthefuel return hose, then dis-connect it from the fuel pressure regulator. Disconnect the vacuum hoses and 2P connector from the EVAp purgecontrol solenoid valve.
4. Remove the retainer nuts on the fuel rail.
5. Disconnect the fuel rail.
6. Removethefuel injectors from the intake manifold.
D16Y5, D16Y8 engine:
NOTE: lllustration shows D16Y8 engine.
D16Y5 engine is similar.
12 N.m11.2 kgl.m,8.7 rbt.ft)
12 N.m11.2 lgl.m,8.7 rbt.ftl
.q
wE4
Y
Ve
ffi}Yg
E
O.RINGReplace.
CUSHIONRINGReplace.
O.RINGReplace.
cusl{toNRINGReplace.
SEALRINGReplace.
ffi
E
EV
R
w
t
YEVAPPURGE CONTNOLSOLENOID VALVE
FUEL
11-232

Fuel Supply System
Fuel Pressure Regulator
Te3ting
@ Do not smoke during the tast. Keep open
flamcs away from your work arsa.
1. Attach the special tool(s) to the service port on the
fuel filter (see pages 1 1-230, 231).
Pressure should bo:
except 81642 engine
260 - 310 kPa |'2.7 - 3.2 kgllcrn2,38 - /t6 psil
816A2 engine:
27O - 320 kPa 12.8 - 3.3 kgf/cm,, 40 - 47 psi)
{with the tuel pressure regulator vacuum hose
disconnested and pinched)
Reconnect the vacuum hose to the fuel pressure
regulator.
Check that the fuel pressure rises when the vacuum
hose from the fuel pressure regulator is disconnected
again.
lf the fuel pressure did not rise, replace the fuel
pressure regutalor.
CLAMP
REGULATOR
11-234
Reolacement
@@ Do not smoke while working on luel sys-
tem. Keep open flame away from your work area,
1. Place a shop towel under the fuel pressure regulator,
then relieve fuel pressure (see pages 11-230,231l..
2. Disconnect the vacuum hose and fuel return hose.
3. Remove the two 6 mm retainer bolts and the fuel
pressure regurator.
Apply clean engine oil to a new O-ring. and carefully
install it into its proper position.
Install the fuel pressure regulator in the reverse
order of removal.

I
FuelFilter
Replacement
r@. Do not smoke whilc working on fuel system. Keep
open flame away from your work arsa.
. While replacing the tuel filter, be catelul to koep a
sale distance betwoen battery torminals and any
tools.
The fuel filter should be replaced whenever the fuel
pressure drops below the specified value [260 - 310 kPa
12.7 - 3.2 ksl/cm',38 - 46 psi), |270 - 320 kPa (2.8 - 3 3
kgf/cm,, 40 - 47 psi))* with the fuel pressure regulator
vacuum hose disconnected and pinchedl after making
sure that the fuel pump and the fuel pressure regulator
are OK. *: 81642 engine
1. Place a shop towel under and around the fuelfilter.
2. Relieve fuel pressure (see pages 11-230,231]-
Remove the 12 mm banjo bolt and the fuel feed
pipe from the fuel filter, while supporting it with the
another wrench, as shown.
Remove the fuel filter ciamp and fuel filter'
lnstall the new fuel filter in the reverse order
removal, and note these items:
a When assembling, use new washers as shown
. Clean the flared joint of high pressure hoses
thoroughly before reconnecting them.
I
,96 MODELS:
(3.4 kgl.m,25 rbf.ftl
,97 AND LATER MODELS:
12 mmBANJOBOLT33 N.m
12 mmBANJOBOLT33 N.mt3.4 kgf m,25 lbf.fr)
\i(o-r
)
11-235