1996 HONDA CIVIC Engine control

Emission Control System
Exhaust Gas Recirculation (EGR) System (D16yS engine)
Doscription
The EGR system is designed to reduce oxides of nitrogen emissions (NOx) by recirculating exhaust gas through the EGRvalve and the intake manifold into the combustion chambers. lt is composed of the EGR valve. EGR vacuum conrrot vatve.EGR control solenoid valve. ECM and various sensors.The EcM contains memories for ideal EGR valve lifts for varying operating conditions, The EGR valve lift sensor detectsthe amount of EGR valve lift and sends the information to the ECM. The ECM then compares it with the ideat EGR valve liftwhich is determined by signals sent from the other sensors. lf there is any difference between the two. the EcM cuts cur-rent to the EGR control solenoid valve to reduce vacuum applied to the EGR valve.
EGR CONTROLCVT: SOLENoID vALvE
EGN VALVE LIFT SENSOR
BLK
I
I
11-254

Emission Control System
Exhaust Gas Recirculation (EGR) System (D16Y5 engine with GWI (cont'dl
lTl49il T_he scan tool indicates Diagnostic Trouble Code (OTC) P1491: A malfunction in the Exhaust Gas Recirculation- lEgh) svstem.
CvT lM/T see page 1l-2611:
J
EGR VALVELIFT SENSOR#16 HOSE
PUMP/GAUGE,0- 30 in.HsA973X-041-XXXXX
EGRVALVE
The MIL has been reoorted on.DTC P1491 is stoled.
Problem verification:1. Do the ECM/PCM Reset Proce-du re.2. Connect the SCS service con'
3. Start the engine. Hold theengine at 3,000 rpm with noload {in Park or neutral) untilthe radiator fan comes on,4. Drive the vehicle on the roadfor approx. 10 minutes. Try tokeep the engine speed in the1,700 - 2,500 rpm range.
Intermittonl failure, system is OKat this time. Check for Door con-nections or loose wires at, C144{EGR velve} and ECM/PCM.
ls DTC P l49l indicated?
Check fo. vacuum to ihe EGR
1. Disconnect the No. 16 hose fromthe EGR valve.2. Connect a vacuum pump/gauge to the hose.3. Start the engine and let it idle.
ls there any vacuum?
Check tor a malfunction in theEGR control solenoid valve:'1. Disconnect the EGR controlsolenoid valve 2P connector,2. Becheck the No. 16 hose for
Check vacuum hose routing o,the entire EGR svstem. lf hoserouting is OK, replac€ the EGRcontrol solenoidvalv6.
ls there any vacuum?
Substitute a known-good ECM/PCM and recheck. It symptom/indicalion goes away, replacethe original ECM/PCM.
(To page 11 257)
11-256

I
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Wire side of lemale terminals
PCM CONNECTORS C (31P)*
ECM CONNECTOR O {I5PI
Wire side of temale terminals
t
(From page 11-258)
Check for a 3hort in the wire
{EGRL linel:Check for continuity betweenECM/PCM connector terminal Dg
Repair op€n in the wire betweenth6 EGR valve and the ECM/PCM(D9 tc6trt.
ReDair short in the wirc batweonthe EGR valve and ECM/PCM {Og(c5t*).
(From page 11-258)
11,260)
Check ths vacuum routing:'1. Recon nect the vacuumpump/gauge to the No. 16hose.2. Start the engine and let it idle.3. At the EGR control solenoidvalve side, connect the bat-tery positive terminal to theEGR control solenoid valveconnectot terminal No. 1.4. While watching the vacuumgauge, connect the batterynegative terminal to the EGRcontrol solenoid valve 2P con-nector terminal No. 2,
ls there approx.26.7 kPa
1200 mmHg,8.0 in.Hg) ofvacuum within 'l second?Chock the vlcuum hos6s:1. Turn the ignition switch OFF.2. Inspect the No. 16 and No. 10hoses for leaks, restrictions ormtsrouUng.
EGR CONTROL SOLENOID VALVE
2P CONNECTOR
Terminal side oImale lerminals
(cont'd)
11-259

Emission Control System
Exhaust Gas Recirculation (EGR) System (Dl6Y5 engine with CW) (cont'dl
tJ
(From page 11-259)EGR CONTROL SOLENOIDVALVE 2P CONNECTOR {C142}
Wire sideof lemaleterminals
ECMCONNECTORa t32Pl
Chock lor an open in the wire (E
SOL linsl:1. Turn the ignition switch OFF.2. Disconnect the 2P connectorIrom the EGR control solenoid
3. Disconnect the ECN4/PCM con-nector A (32P) (B (25P))* fromthe EcM/PCM.4. Check tor continuity betweenECM/PCl, connector terminal47 (86)* and the EGR controlsolenoid valve 2P connectorterminal No.2.
Repair opon in th. wir. bstwocntha EGR control 3ol€noid valvoand tho ECM/PCM (A7 186l'1.
ls there continuity?
Check for . rhort in the wire(ESOL linel:Check for continuity between theEGR controlsolenoid valve 2P con-nector terminal No. 2 and bodyground,
R.p.ir ahort in tha wi.c b.twecnthe EGR control iolonoid vllyeand th. ECM/FCM {A7 (46}rl.
Check for an opon in the wiroIGND linel:Check for continuity between theEGR controlsolenoid vaive 2P con-nector terminal No. I and bodyground,
Rcpai. op€n in the wir6 b6'twoenthe EGR control rol.noid valveand G101.
Sub3titule a known-good ECM/PCM and rechock. lf symptom/indication goes away, replac€the original ECM/PCM.
ESOL
IRED)
ESOLIRED)
Wire sideof femaleterminals--_-]
I
EGR CONTROL SOLENOIDVALVE 2P CONNECTOR ICl'2}
Wire sideof femaleilterminals
ECMCONNECTORB l25P)ESOL(REDI
Wire sideof femalerermtnats
*: '99 - 00 models
11-260

Emission Control System
(From page 11-261)
Check tor open in the wire (SG2
linel:Measure voltage between theECM connector terminals D10and D11.
Repsir open in lhe wire beiweenECM lOllland EGR valve.ls there approx. 5 V?
Check the EGR valve:1. Turn the ignition switch OFF.2, At the sensor side, measureresistance between the EGRvalve 6P connector terminalsNo. 1 and No. 2.
ls there continuity or resis-tance of 100 k0 or higher?
Check the EGR valve:Measure resistance between theEGR valve 6P connector terminals No. 1 and No.3.
ls there 100 k0 or higher?
Exhaust Gas Recirculation System (D16Y5 engine with M/T) (cont'dl
ECM CONNECTOR D {16P)
vcc2(YEL/BLU)
\v
sG2IGRN/BLK)
Wire side of female term;nals
EGR VALVE 6P CONNECTOR
EGR L(WHT/
BLK}
SG2 (GRN/BLK)
Termanal side of male terminals'l'
EGR L{WHT/BLK}
vcc2
{YEL/BLU}
(To pase 11 263)
1-262

Emission Gontrol System
Exhaust Gas Recirculation System (Dl6Y5 engine with M/Tl (cont'dl
lFrom page 11 263)EGR VALVE6P CONNECTOR {C144}
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Wire sideof femaletermtnals
J
Check lor an op€n in the wire (E-
EGR line):1. Turn the ignition switch OFF.2. Disconnect the ECM connector,A (32P)trom the ECM.3. Check lor continuity betweenECM connector terminal A7and the EGR valve 6P connec-torterminal No. 6.
Repair open in the wiro botweenthe EGR valv6.nd th€ ECM {A71.
Check tor a short in the wire {E-EGR lin6l:Check for continuity betweenECM connector terminal A7 andbody ground.
Reoair shorl in tho wiro belwe€nthe EGn vake rnd the ECM lA7l.ls there continuity?
Check fo. an open in tho wiro
IGND line):Check for continuity between theEGR valve 6P connector terminalNo.4 and body ground.
R6pai. open in th€ wir. betweenth6 EGF control solenoid v6lveand G101.
Substitute 8 known-good ECMand recheck. It symptom/indica-tion goes away, roplace the origi-nalECM.
CONNECTORA l32P)
2
a
I G101
Q) raur
-264

Emission Control System
Positive Crankcase Ventilation IPCVI System
Descripiion
The Positive Crankcase Ventilation (PCV) system is
designed to prevent blow-by gas from escaping to the
atmosphere. The PCV valve contains a spring-loaded
plunger. When the engine starts, the plunger in the PCV
valve is lifted in proportion to intake manifold vacuum
and the blow-by gas is drawn directly into the intake
manifold.
D15Y5, D16Y8, 816A2 ongins:
BREATHERHOSE
Dl6'|11 6ngin6:
-: aLOW-BY VAPOR-: FnESH AIF
11-266
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lrcpection
1. Check the PCV hoses and connections for leaks and
clogging.
2. At idle, make sure there is a clicking sound from the
PCV valve when the hose between the PCV valve
and the intake manifold is lightly pinched with your
fingers or pliers,
D16Y5, D16Y8 ongins:
BREATHERHOSE
PCV VALVE
Gently pinch here.
Bl6A2 engins:VALVE
lf there is no clicking sound, check the PCV valve
grommet for cracks and damage. If the grommet is
OK, replace the PCV valve and recheck.
PCV

1\
Evaporative Emission (EVAPI Controls
Description
The evaporative emission controls are designed to minimize the amount of fuel vapor escaping to the atmosphere. The
system consists of the foliowing components:
A. Evaporative Emission (EVAP) Control Canisto]
An EVAP control canister is used for the temporary storage of fuel vapor until the fuel vapor can be purged from the
EVAP control canister into the engine and burned.
B. Vapor Purge Control System
EVAP control canister purging is accomplished by drawing fresh air through the EVAP control canister and into a port
on the intake manifold. The purging vacuum is controlled by the EVAP purge control solenoid valve.
I'96 D16Y5 engine,'96 Dl6Y7 engine,'96 D16Y8
engine (sedan),'97 D16Y5 engine,'97 D16Y7
engine (couper KA, KC models, sedan: KA, Kc'
KL iDX) models, hatchback: all models), '97
D 16Y8 engine (sedan: KA, KC models)l
I'96 D16Y8 engine (coupe),'97 D16Y7 engine
(coupe: KL model, sedan: KL (LX) model)"97
D16Y8 engine (coupe: all models, sedan: KL model)'98-all models,'99-all models,'00-all modelsl
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c.
D.
or
l'lc COMPRESSOR CLUTCH ON
and
INTAKE AIR TEMPERATURE ABOVE 160"F (41'C)
Fuel Tank Vapor Control System
When fuel vapor pressure in the fuel tank is higher than the set value of the EVAP two way valve, the valve opens and
regulates the flow of fuel vapor to the EVAP control canister.
Onboard Refueling Vapor Recovery (ORVRI System {'99 - 00 models}
During refueling. the oRVR {onboard Refueling Vapor Recovery) vent shut valve opens with the pressure in the fuel
tank. and feeds the fuel vapor to the EVAP control canister.
t(cont'd)
11-267
EVAP PURGE CONTROL SOLENOID VALVE DUTY CON-
TROLLED AFTER STARTING ENGINE
ENGINE COOLANT TEMPERATURE ABOVE 154'F {68"C)
INTAKE AIR TEMPERATURE ABOVE 32'F (O'C)
and
VEHICLE SPEED ABOVE O MILE (O KM/h}
ENGINE COOLANT TEMPERATURE ABOVE 154'F (68'C)