Nissan PULSAR N13 Series / ASTRA LD Series. Manual — part 29

117

EMISSION CONTROL

INTRODUCTION

To reduce the output level of the three primary

automotive emissions, carbon monoxide (CO), hydro-
carbons (HC) and oxides of nitrogen (NOx), and thus
comply with legislation on the maintenance of clean
air, several different emission control systems are used
in the Pulsar range of vehicles covered by this manual.

The systems will be discussed under the headings

(1) Crankcase Ventilation System, (2) Evaporative
Control System, (3) Air Preheat System — 1.6 Liter
Engine and (4) Exhaust Control System.

1. CRANKCASE VENTILATION SYSTEM

DESCRIPTION

The crankcase ventilation system is of the closed

type and is designed to prevent crankcase vapors
being emitted into the atmosphere. Crankcase
vapors are caused by gases escaping past the piston
rings into the crankcase during the combustion pro-
cess.

The crankcase vapors are collected in the cam-

shaft housing from the crankcase via the various oil
drain passages and the pipe from the side of the
crankcase.

The crankcase vapors are then drawn into the

engine via a branched hose connected to the camshaft
housing oil baffle and the throttle body (1.8 liter
engines) or inlet manifold (1.6 liter engines).

At idle speed, vapors are drawn through the

small branch of the hose and into the engine.

As the engine speed increases, vapors are also

drawn into the engine via the main hose.

TO SERVICE THE SYSTEM

(1) At intervals of 40 000 km, disconnect the

small engine ventilation hose from the throttle body
or inlet manifold and check that the metering orifice
is not blocked.

If necessary, clean the orifice using compressed air

and solvent.

(2) Disconnect all the engine ventilation hoses

and check for blocking, collapsing and deterioration.
Renew the hoses as necessary.

2. EVAPORATIVE CONTROL SYSTEM

Special Equipment Required:

To Test Purge Valve — Hand vacuum pump

DESCRIPTION

The evaporative control system reduces the

amount of hydrocarbons emitted to the atmosphere
through fuel evaporation.

The vehicles covered by this manual use an

absorption regeneration system to reduce vapor loss.
The system utilizes a canister of activated charcoal to
trap and hold the fuel vapors until they can be fed
into the induction system for burning in the combus-
tion chambers.

The basic components of the evaporative control

system are a fuel tank with a sealed filler cap, a
charcoal canister with a purge control valve, a fuel
check valve and pipes and hoses to connect the
various components.

NOTE: The fuel tank filler cap is not vented
to the atmosphere but is equipped with a one
way relief valve to prevent a vacuum form-
ing in the fuel tank.

View of the engine ventilation hoses and pipe. 1.8 liter

engine.

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Emission Control

Installed view of the charcoal canister.

When the engine is at rest, fuel vapor through

evaporation gradually fills the air space in the fuel
tank. The sealed filler cap prevents the escape of this
vapor and pressure builds up within the system,
forcing the vapor to flow into the charcoal canister
which is located in the engine compartment beneath
the windscreen wiper motor.

The fuel check valve prevents liquid fuel entering

the charcoal canister when the fuel tank is full or the
vehicle is parked on a steep incline. When the engine
is running, the vapor is drawn via a hose from the
charcoal canister to the throttle body and burnt in the
combustion chambers.

TO RENEW CHARCOAL CANISTER

(1) Suitably mark and disconnect the hoses from

the canister.

(2) Release the retaining spring and remove the

canister from the engine compartment.

Installation is a reversal of the removal procedure.

TO RENEW FUEL CHECK VALVE

(1) Disconnect the negative battery terminal.

(2) Raise the rear of the vehicle and support it

on chassis stands. Remove the left hand rear wheel.

(3) Drain the fuel from the fuel tank using a

hand pump or a suitable siphon. Do not siphon fuel
using the mouth.

(4) Remove the hoses from the check valve.
(5) Squeeze the retaining clip and remove the

check valve from the mounting bracket.

Installation is a reversal of the removal procedure.

TO SERVICE THE SYSTEM

(1) Inspect the vacuum lines and connectors for

signs of leakage, cracks and deterioration and renew
as necessary.

(2) Remove the fuel tank cap and check that a

slight resistance is felt, when vacuum is applied to the
one-way relief valve in the centre of the cap.

Renew the fuel tank cap if no resistance is felt or

if the valve is blocked.

(3) Inspect the fuel tank cap seal for deteriora-

tion. Renew as necessary.

Installed view of the fuel check valve as seen with the

left hand rear wheel removed.

Check the fuel filler cap seal for damage.

23Q/LDZ GAUGE

Line drawing showing a hand vacuum pump.

Emission Control

119

(4) Remove the charcoal canister as previously

described under the heading To Renew Charcoal
Canister.

(5) Shake the canister, there should no audible

carbon movement. If there is, renew the canister.

(6) Check the purge valve by applying 20-35

kPa of vacuum with a hand pump to the control port.

Using a piece of hose, blow through the purge

hose connection. If this is not possible, renew the
canister.

Remove the vacuum source and blow air through

the purge hose connection. If this is possible, renew
the canister.

(7) Apply 20-35 kPa air pressure into the fuel

tank connector. Air should flow freely from all the
other connectors.

If poor air flow through the drain tube exists,

block off the fuel tank tube and blow compressed air
at approximately 300 kPa through the purge port.
Check the air flow and if still poor, renew the canister.

(8) Apply 20-35 kPa air pressure to any one of

the canister ports except the purge valve control port
and with the other ports blocked, ensure that there are
no leaks from the canister. If leaks exist, renew the
canister.

(9) Remove the fuel check valve as previously

described under the heading To Renew Fuel Check
Valve.

(10) Blow through the check valve from the side

that is connected to the fuel tank hose. Considerable
resistance should be felt with only a small amount of
air passing through the valve. If no resistance is felt or
if the valve is blocked renew the fuel check valve.

(11) Blow air through the fuel check valve from

the opposite end. There should be a smooth flow of air
through the valve. If the valve is blocked, renew the
fuel check valve.

3. AIR PREHEAT SYSTEM — 1.6 LITRE

ENGINE

DESCRIPTION

To reduce emissions and improve drivability

when the engine is cold, hot air is drawn into the air
cleaner from a heat shield which partially surrounds
the exhaust manifold.

When the ambient temperature is below 30°C, the

thermal vacuum valve, which is located inside the air
cleaner housing, allows vacuum to operate a servo
actuated flap in the air cleaner intake duct. When the
flap closes, hot air is drawn from the exhaust heat
shield, through the hot air inlet tube into the air
cleaner intake duct.

When the ambient temperature is above 30°C,

the flap in the air cleaner intake duct opens allowing
cool air to enter the air cleaner.

View of the air preheat system components. 1.6 liter

engine.

TO CHECK OPERATION

(1) When the engine is cold, use a mirror to

check that the passage from the hot air inlet tube is
closed by the flap.

(2) Start and run the engine at approximately

1 200 rpm. The hot air inlet passage should now be
open, allowing hot air from the exhaust heat shield to
be drawn into the air cleaner.

(3) Allow the engine to idle for fifteen minutes

and inspect the position of the air cleaner intake flap.
The flap should now be in the open position allowing
cool air to be drawn into the air cleaner and shutting
oft' air from the exhaust manifold heat shield.

TO CHECK COMPONENTS

(1) Disconnect the vacuum hose from the servo

unit and connect a vacuum pump to the unit.

When the vacuum is applied to the servo unit, the

flap in the air cleaner intake duct should close.

When the vacuum is removed, the flap should

open.

View of the air cleaner raised showing the engine

ventilation hose and the thermal vacuum valve supply

hose connection. 1.6 liter engine.

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Emission Control

If the flap does not operate as described, renew

the air cleaner housing.

(2) Disconnect the vacuum hose from the servo

unit and connect it to a vacuum gauge.

(3) Start and run the engine at approximately

1 200 rpm. If the engine is cold there should be
vacuum.

(4) As the engine temperature increases the

vacuum should decrease to zero.

If the vacuum gauge does not read as described,

check that the vacuum supply hose is connected to the
thermal vacuum valve and the throttle body.

If no fault is found, renew the thermal vacuum

valve.

4. EXHAUST CONTROL SYSTEM

DESCRIPTION

The exhaust system is the greatest source of

pollutant emission from the internal combustion
engine.

On the Pulsar range of vehicles covered by this

manual, the exhaust control system consists of a
catalytic converter and the engine management sys-
tem. The engine management system constantly mon-
itors the exhaust gases via an oxygen sensor located in
the exhaust system. Fuel injection is then adjusted
accordingly to give the minimum amount of exhaust
emissions. Refer to the Fuel and Engine Management
section for further information.

CATALYTIC CONVERTER

The catalytic converter, which is located in the

exhaust system, converts hydrocarbons, oxides of
nitrogen and carbon monoxide present in the exhaust
gases into carbon dioxide, nitrogen, water and heat.

The catalytic converter does not require periodic

maintenance or replacement under normal circum-
stances. However, it can be damaged or poisoned by
excessively high exhaust gas temperatures, raw fuel
and the use of leaded fuel.

Installed view of the catalytic converter.

To prevent the use of leaded fuel, a small diam-

eter fuel filler neck with a spring loaded trap door is
used.

To prevent damage to the catalytic converter, the

following precautions should be observed.

(1) Do not operate the vehicle on leaded fuel.
(2) Do not push or tow start the vehicle.
(3) Do not allow the engine to idle for prolonged

periods.

(4) Do not operate the vehicle if the engine is

misfiring.

(5) Avoid running the vehicle out of fuel.
(6) Ensure that the engine oil is formulated to

contain low phosphorous levels.

To Inspect Catalytic Converter

(1) Inspect the converter for dents and damage.

If the converter is damaged, it should be renewed.

(2) Inspect the converter heat shield for damage

and ensure that it is positioned correctly. Renew the
converter heat shield if necessary.

To Remove and Install

To remove and install the catalytic converter,

refer
to the Exhaust System heading in the Engine section.