1999 HONDA CIVIC ect

IThrottle BodY
Description
The throttle bodY is either a single-barrel side-draft type
(D16Y5, D16Y8, 816A2 engine) or a down-draft type
(D16Y/ engine). The lower portion ot the throttle valve is
heated by engine coolant from the cylinder head' The
idle adjusting screw which regulates the bypass air is
located on the top of the throttle body
THROTTLEPOS|T|ON lTPlSENSOR
IDLE AD.'USTINGSCREW
t
In3pection
1. Check that the throttle cable operates smoothly
without binding or sticking.
lf there are any abnormalities, check for:
. Excessive wear or play in the throttle valve shaft'
. StickY or binding throttle lever at the fully closed
Position.. Clearance between throttle stop screw and throt-
tle lever at the fully closed position'
D16Y5, Dl6Y8 engine:
THROTTLE STOP SCREW
{Do not adjust.)
Dl6Y7 ongine:
816A2 engins:
THROTTLE LINK
STOP SCREW
THROTTTE STOP SCREW(Do not adjust.)
Replace the throftle body if thsre is excessive play in the
throttle valve shaft or iJ the shaft is binding or sticking'
(cont'd)
11-247
{Do not adjust.)

Intake Air System
Fuel Injection Air (FlA) Controt System I'99 - 00 Dl6yg enginel
Dsscription
When the engine running lengine coolant below 149oF (6S"C)], the fuel Injection Air (FtA) Control Valve sends intake air tothe fuel iniectors.
E> : INTAKEAIR
FUELINJECTOB
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\J
Fuol Iniection Air {FlA) Contlol Valve T$ting
1. Start the engine.
2. Remove the vacuum hose from the fitting on the
intake air duct, and connect a vacuum gauge to the
nose.
NOTE: Engine coolant temperature must be below
149"F (65"C).
VACUUM PUMP/GAUGE,
0-30 in.Hg.A973X - 041 -XXXXX
Raise and lower the engine speed, and make sure
the vacuum gauge reading changes as the engine
speed changes.
lf vacuum reading does not change check these
rtems:
. The vacuum lines of FIA system for misrouting,
leakage, breakage and clogging.
. The FIA controt valve for cracks or damage
. The cooling system (see section 10).
Hold the engine at 3,OOO rpm with no load (in Park
or neutral) until the radiator fan comes on, th€n let
it idle and recheck.
lf vacuum reading changes check these items:
a The FIA control valve for cracks or damage.
. The cooling system (see section 10).
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Emission Gontrol System
System Description
The emission control system includes a Three Way Cata-lytic Convener (TWC), Exhaust Gas Recirculation (EGR)
system,. Positive Crankcase Ventilation (pCV) system andEvaporative Emission (EVAP) Control system. The emis-sion control system is designed to meet federal and stateemission standards.*: D16Y5 engine
Tailpipe Emission
Inspestion
@@ Do not smoke during ihis procedure. Keepany open flame away from your work area.
1. Start the engine. Hold the engine at 3,000 rpm withno load (in Park or neutral) until the radiator fancomes on. then let it idle.
2. Connect a tachometer.
Check and, if necessary, adjust the idle speed (see
page 11-220 - 223).
Warm up and calibrate the CO meter according to themeter manufacturer's instructions.
Check idle CO with the headlights, heater blower,rear window defogger, cooling fan, and air condition-er off.
NOTE: (Canada) Pull the parking brake lever up.Start the engine, then check that the headlights areoff.
CO mete. should indicate 0.1% maximum.
NOTE: '98 Dl6Y5 engine - lf the idle speed incress-es to 8101 50 rpm, this means the EVAp system ispurging the canister. To stop the purging temporari-ly. raise the engine speed above 1,000 rpm with theaccelerator pedal, then slowly release the pedal.
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eFORWARD -
Three Way Catalytic Converter
(TWCI
Doscription
The Three Way Catalytic Converter (TWC) is used toconven hydrocarbons (HC), carbon monoxide (CO), andoxides of nitrogen (NOx) in the exhaust gas to carbondioxide (COr), dinitrogen (N,) and water vapor.
D15Y5, D16
, engine:
'99 - 00 D16Y8, 81642 engine:
ENGINE SIDE
t

\
lTo420l Th" """n toot indicates Diagnostic Troubte code (DTc) p0420: catatyst sysrem efficiency below threshold.
Description
This system evaluates the catalyst's capacity by means of the Ho2s {Primary and secondary) output during stable driving
conditions. ll deterioration has been detected during two consecutive driving cycles. the MIL comes on and DTC P0420 will
be stored.
NOTE: lf some of the DTCS tisted below are stored at the same time as DTC P0420, troubleshoot those DTCS first. then
recheck for DTC P0420
P0137, P0138: Secondary HO2S (Sensor 2)
Po14'1:Secondary H02S {Sensor 2) Heater
Possibl€ Cause
. TWC Deterioration
. Exhaust system leakage
Troubleshooting Flowchart
I
The MIL has been reported on.
DTC P0420 is stored
Problem verilication:1. Do the ECM/PCM Reset Proce
dure.2. Start the engine Hold the
engine at 3,000 rpm wath no
load {in Park or neutral) until
the radiator fan comes on.
3. Connect the SCS service con
4. Test drive 40 - 55 mph for
approx, two minutes Then
decelerate for at least 3 sec_
onds with the throttle com'pletely closed- Then reduce
the vehicle speed to 35 mph,
and try to hold it until the
readiness code comes on
Intermittent Iailure, system is OK
at this time.ls DTC P0420 indicated?
Check the TWC {see section 9l
lf necessary, replace the TwC

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
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4
The scan tool indicates Dlagnostic Trouble cod€ {DTc} Po4ol: lnsufficient flow in the Exhaust Gas Recirculation
(EGR) svstem.
Doscription
Deterioration (clogging, leakage, etc.) in the EGR line or EGR valve is detected by means of the changes in MAP before
and after the operation of the EGR valve.
lf deterioration has been detected during two cons€cutive driving cycles, the MIL will come on and DTC P0401 will be
stored.
Po$ible Causeg
. Clogging. leakage in the EGR line
. Faulty EGR valve
Troubleshooting Flowchart
\
- Tho MIL ht! bacn rgportod on.- DTC m40l is 3torod.
Problom vorification:
1. Do the ECM/PCM Reset Proce-
dure.2. Connect the SCS service con-
nector,3. Tost-drive under the following
conditions.- Without any electrical load- Decelerate lrom 55 mPh(88 km/h)lor at least 5 sec-
onos
lntormiftam f!ilu.a, ayltam ia OK
.t thb time,
- Clo.n tho inttkc mlnifold EGRport wittr carbursto. clotner.- Cl.an the pa$lgo insido tho
EGR valvo with crrburator
cloanol or aoglaca tha vllvo.

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)
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