1995 ACURA TL Service Repair Manual

Testing
Intake Ai r Bypas s (IAB ) Lo w Contro l Valv e
1 . Disconnec t th e No . 2 vacuu m hos e fro m th e vacu -
u m hos e manifold , an d attac h a vacuu m pum p to th e
vacuu m hos e manifold .
IAB LO WCONTRO L SOLENOI D VALV E
No. 2 VACUUM HOSE
2.
VACUU M PUMP /GAUG EA973X - 04 1 - XXXX X
Apply vacuu m an d verif y tha t th e IA B contro l dia -
phrag m valv e hold s vacuu m an d tha t a s th e vacuu m
i s applie d an d release d th e IA B contro l diaphrag m
valv e ro d move s i n an d out .
I f th e IA B contro l diaphrag m valv e doe s no t hol d
vacuu m o r th e IA B contro l diaphrag m valv e ro d
doe s no t mov e i n an d out , replac e th e IA B con -
tro l valv e an d retest . Intak
e Ai r Bypas s (IAB ) Hig h Contro l Valv e
1.Disconnec t th e No . 8 vacuu m hos e fro m th e vacu -
u m hos e manifold , an d attac h a vacuu m pum p t o
th e vacuu m hos e manifold .
IAB HIG H
CONTRO L SOLENOI D VALV E
No. 8 VACUU M HOS E
2.Appl y vacuu m an d verif y tha t th e IA B contro l
diaphrag m valv e hold s vacuu m an d tha t a s th e vac -
uu m is applie d an d release d th e IA B contro l dia -
phrag m valv e ro d move s in an d out .
I f th e IA B contro l diaphrag m valv e doe s no t hol d
vacuu m o r th e IA B contro l diaphrag m valv e ro d
doe s no t mov e i n an d out , replac e th e IA B con -
tro l valv e an d retest .
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Emission Contro l Syste m
Three Wa y Catalyti c Converte r (TWC )
Descriptio n
The Thre e Wa y Catalyti c Converte r (TWC ) i s use d t o conver t hydrocarbon s (HC) , carbo n monoxid e (CO) , an d oxide s o f
nitroge n (NOx ) i n th e exhaus t ga s to carbo n dioxid e (CO
2), dinitroge n (N2) an d wate r vapor .
SECONDAR Y HEATE D OXYGEN SENSOR (SENSO R 2 )
HOUSIN G
THREE WA YCATALYST SFRONT O F
VEHICL E
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Emission Control System

Exhaust Gas Recirculation (EGR) System

Description

The EGR system is designed to reduce oxides of nitrogen emissions (NOx) by recirculating exhaust gas through the EGR

valve and the intake manifold into the combustion chambers. It is composed of the EGR valve, EGR vacuum control valve,

EGR control solenoid valve, PCM and various sensors.

The PCM contains memories for ideal EGR valve lifts for varying operating conditions. The EGR valve lift sensor detects

the amount of EGR valve lift and sends the information to the PCM. The PCM then compares it with the ideal EGR valve lift

which is determined by signals sent from the other sensors. If there is any difference between the two, the PCM cuts cur-

rent to the EGR control solenoid valve to reduce vacuum applied to the EGR valve.

EGR VALVE

LIFT SENSOR
INTAKE

MANIFOLD

From No. 4 ECU (PCM)

FUSE (15 A) or (20 A)

(in the under-dash

fuse/relay box)

EGR

CONTROL

SOLENOID

VALVE

EGR

VACUUM

CONTROL

VALVE
VARIOUS

SENSORS
EGR VALVEProCarManuals.com

Emission Control System

Positive Crankcase Ventilation (PCV) System

Description

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.

INTAKE

MANIFOLD
BREATHER PIPE

PCV HOSE

PCV VALVE

BLOW-BY VAPOR

FRESH AIR
Inspection

1. Check the PCV hoses and connections for leaks and

clogging.

PCV HOSE

BREATHER

PIPE

PCV VALVE

2.
At idle, make sure there is a clicking sound from the

PCV valve when the hose between the PCV valve

and intake manifold is lightly pinched with your fin-

gers or pliers.

Gently pinch here

If there is no clicking sound, check the PCV valve

grommet for cracks or damage. If the grommet is

OK, replace the PCV valve and recheck.ProCarManuals.com

Evaporative Emission (EVAP) Controls

Description

The evaporative emission controls are designed to minimize the amount of fuel vapor escaping to the atmosphere. The

system consists of the following components:

A. Evaporative Emission (EVAP) Control Canister

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 throttle body. The purging vacuum is controlled by the EVAP purge control solenoid valve.

'96 model:
'97 - 98 models:

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.

'96 model:

INTAKE MANIFOLD
THROTTLE

BODY

EVAP PURGE

CONTROL

SOLENOID VALVE

FUEL TANK

EVAP VALVE
EVAP TWO WAY VALVE
From

No. 4 ECU
(PCM) (15A)

FUSE (in the under-dash

fuse/relay box)

EVAP

CONTROL

CANISTER FRESH

AIR
EVAP PURGE

FLOW SWITCH

FUEL FILL CAP
PCM
VARIOUS

SENSORS

FUEL TANK
ENGINE COOLANT TEMPERATURE ABOVE 158°F (70°C)
ENGINE COOLANT TEMPERATURE ABOVE 99°F (37°C)
EVAP PURGE CONTROL SOLENOID VALVE DUTY CON-

TROLLED AFTER STARTING ENGINE
EVAP PURGE CONTROL SOLENOID VALVE OFF AFTER

STARTING ENGINEProCarManuals.com

Emission Contro l Syste m
Evaporativ e Emissio n (EVAP ) Control s (cont'd )
'97 - 9 8 models :
INTAKE
MANIFOL DTHROTTL EBODY
FromNo. 4 EC U (PCM )(20 A ) FUS E
(i n th e under-das h
fuse/rela y box )
EVAP CONTROL CANISTERVENT SHUT VALVE
EVAP TWO WAY VALVE
EVAPCONTROLCANISTER
VARIOU SSENSOR S
EVAP BYPAS SSOLENOI D VALV E
FUEL TAN K
FUE L TAN K
PRESSUR E
SENSO RFUE
L TAN K
EVA P VALV E FUE
L FIL L CA P
PCM
EVA P PURG ECONTRO LSOLENOI D VALV E
EVAP THRE EWAY VALV E
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Evaporative Emissio n (EVAP ) Contro l Caniste r an d EVA P
Contro l Caniste r Ven t Shu t Valv e Replacemen t
1 . Remov e th e fron t bumpe r (se e sectio n 20 ).
2 . Remov e th e EVA P contro l canister .
EVAPCONTRO L CANISTE R
COVER
3. Remov e th e EVA P contro l caniste r ven t shu t valve .
EVAPCONTRO LCANISTERVENTSHUTVALV E
O-RINGReplace .
Evaporativ e Emissio n (EVAP ) Tw o Wa y Valv e an d EVA P
Bypas s Solenoi d Valv e Replacemen t
O-RINGReplace .
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Special Tool s
14-176 , 14-19 4
14-185 , 14-18 8
14-14 3
14-12 8
14-19 7
14-185 , 14-18 8
14-14 3
14-168 , 14-169 , 14-192
14-21 3
14-114 , 14-11 8
14-114 , 14-11 8
14-65
14-66 , 14-10 8
14-114 , 14-11 8
14-114 , 14-11 8
14-198 , 14-19 9
14-176 , 14-19 1
14-198 , 14-19 9
14-193 , 14-197 , 14-198
14-20 7
14-191 , 14-193 , 14-194
14-197 , 14-198 , 14-199
14-141 , 14-20 8
14-19 8
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