1990 HONDA PRELUDE fuel

Evaporative Emission Control System
The Evaporative Emission Control System is designed to prevent
fuel vapors from escaping into the atmosphere.

(2.0 Si,Si)

Fuel vapors from the fuel tank are directed into the charcoal
canister where they are adsorbed and stored while the engine is
stopped or idling. When the coolant temperature rises to a certain
value, the vapors are drawn into the engine through the throttle body and the intake manifold during normal engine operation.
(2.0 S)Fuel vapors from the fuel tank and carburetor are directed into the
charcoal canister where they are adsorbed and stored while the
engine is stopped.
When the engine is running and engine coolant temperature is above
the set temperature of the thermo sensor, the purge control diaphragm valve is open so that fuel vapors in the charcoal canister may be drawn into the engine through the carburetor and the intake
manifold.
Engine Exhaust Controls
The engine exhaust emission control systems are designed to
control combustion during idle, acceleration, cruise, and deceleration.
These systems are entirely separate from the crankcase and evaporative emission control systems described previously. HONDA PGM-FI System (2.0 Si,Si)
The PGM-FI system consists of three independent sub-systems; Air intake, Electronic Control and Fuel Control, thus allowing moreaccurate control of air/fuel ratios under all operating conditions.
The Electronic Control Unit (ECU) detects the amount of air
drawn into the cylinders and determines the amount of fuel to be injected to provide the optimum air/fuel ratio for all engine needs.

(cont'd)ProCarManuals.comMain Menu t s

Emission Controls (cont'd)
Intake Air Temperature Control System (2.0 S)The air control valve mounted inside the air cleaner snorkel
automatically opens and closes according to the intake air
temperature. The carburetor then receives air of constant
temperature which results in lower exhaust emissions.
Carburetor Controls (2.0 S)—Throttle controller — This system controls the throttle during
gear shifting, reducing the amount of HC caused by unburned

fuel mixture.

— Choke opener — When starting a cold engine, this device
opens the choke slightly. This reduces the amount of HC and

CO.

— Altitude Compensation devices — The Air Jet Controller (AJC)
has an atmospheric pressure sensing bellows. The AJC is
designed to control the amount of additional air fed to the
carburetor jets to maintain good driveability at any altitude. Ignition Timing Control System
This system automatically controls the ignition timing to reduce

the amount of HC and NOx.

Exhaust Gas Recirculation (EGR) [Except California 2.0 S models]
The EGR system is designed to control the formation of oxides of nitrogen (NOx) caused when fuel mixture burns at high
temperature. It works by recirculating exhaust gas through the EGR valve and intake manifold into the combustion chambers
where it reduces peak temperature by diluting the air/fuel mixture.
Catalytic Converter
The catalyst is used to convert hydrocarbons (HC), carbon monoxide (CO) and oxides of nitrogen (NOx) in the exhaust gas,
to carbon dioxide (CO 2
), dinitrogen (N 2
) and water vapor.
ProCarManuals.comMain Menu t s

Air Supply System (2.0 S)
A secondary air supply system helps improve emission
performance by promoting more complete combustion during

deceleration.

Air injection with Feedback System (2.0 S)
This system maintains the proper air/fuel ratio for the most
efficient use of the three way catalytic converter by controlling
the amount of air injection in response to the oxygen concentration in the exhaust manifold.ProCarManuals.comMain Menu t s

Catalytic Converter
A catalytic converter is installed in the exhaust system to help
clean-up the exhaust gases that can cause air pollution.
To be effective, the converter must work at high temperature, so don't park your car over dry grass, leaves or anything else that

could burn easily.

To stay effective, the converter must not be contaminated by
leaded gasoline; use only unleaded gas as explained on page 55.

CAUTION:

The converter can be overheated and damaged if it's fed too much unburned fuel mixture from the engine, so:
— Don't push or tow the car to start it; if the battery is dead. jump start the car as shown on page 119.
— Don't turn the key off while the engine is running above idle
speed.

— Don't change the ignition timing, or remove any emission control parts.
— Use only the spark plugs specified in this manual.
— Don't keep driving your car if it isn't running properly, or if its Check Engine warning light comes on; have It checked byyour Honda dealer. CATALYTIC CONVERTERProCarManuals.comMain Menu t s

Index (cont'd)

Emission Controls.........................130

Engine
Coolant.......................................88
Coolant Temperature
Gauge....................................20
Identification Number .............127
Oil and Filter...............................83
Oil Pressure
Warning

Light .......................................22

Specification ...........................125

Exhaust Controls....................131
Engine Exhaust Ga
s Warning

....................................................64

Evaporative Emission Control
System ....................................131
Exhaust Gas Recirculation...........132
Exterior Care.................................110
Filters

Air...........................................94
Engine Oil ...................................84

Fuel.............................................96

Fluid .....................................See "Oil"

Foreign Countries, Operation in ...............................56
Four Wheel Steering.......................59 Front Seat
Adjustment..................................5

Fuel

Filter Door and Cap...................56
Fuel Reserve
Warning

Light .......................................22

Gauge.........................................20

Gasohol......................................55

Gasoline ......................................55

Requirement..............................55

Filter...........................................96
Fuse

Checking and Replacing .........101

Specification...........................126 Gasoline............................See"Fuel"
Gas Station Information
...........................................back cover

Gauges............................................20
Glove Box ........................................39
Hazard Warning

Indicator Light ...........................21
Hazard Warning System................33

Headlights

Flasher.......................................31
Headlight Motor
Switch ...........32

High Beam Indicator..................21
High Beam/Low

Beam

Switch...................................31
If the

Retractable Headlights
do not operate ...................123

Reminder Chime

.......................30

Retractable Headlight Motor Warning Light .......................25

Switch.......................................30
Headlight High
Beam Indicator

Light ...........................................21

Head Restraints.................................8

Heating.............................................45

High Bea
m

Switch .......................................31
Indicator Light ...........................21

Hood Latch.....................................39
Identification Numbers.................127
Ignition
Keys.............................................3

Switch........................................58

Indicator Lights ...............................20
Inflation Pressures, Tire..............105
Instrument Panel....................19
Instrument Panel
Brightness

Control.......................................33

Interior light .....................................33
Interior Trim Care .........................110 Jack .............................................116
Jump Starting ...............................119ProCarManuals.comMain Menu t s

Keys
Door Locks ..................................3
Glove box ..................................39
Trunk Lid Lock ............................4
Ignition ........................................58

Key Reminder Beeper...............58Keys.............................................3
Lap/Shoulder Belts
................................Se
e "Seat Belts"

Light

Bulb Replacement...................103
Fuse Replacement ..................101
Light Reminder
Chime ..............30

Operation.................................30

Warning and Indicator Light
......................................................21
Locks

Fuel Filler Door ..........................56
Doors..........................................3

Glove Bo
x ..................................39

Trunk Lid......................................4

Anti-theft Steering

Column

Lock.......................................58

Lumbar Support,Driver's .................7
Maintenace Schedule
and

Records......................................76

Manual Transmission Maximum Allowable Speeds
....................................................66

Oil........................................86
Recommended Shift
Speeds

....................................................66

Shifting.....................................65

Meters Gauges.......See
"Gauges"
Mirrors Power Mirrors ...........................29
Rear View Mirrors ....................29 Numbers, Identification................ 127

Octane Rating,
Gasoline

.......................................... See "Fuel"
Odometer ........................................20Oil

Engine Oil ...................................83

Fluid Locations ..........................82Transmission Oil/Fluid ..............86Oil Pressure Warning Light.......22
Power Steering Fluid ................97
Operation In
Foreign Countries

..........................................................56

Panel Brightness Control ...............33
Parking Brake.................................
39

Power

Mirrors .......................................29
Steering .....................................
97

Windows................................40

PGM-FI System............................131
Pressures, Tire Inflation...............105
Preventive Service.......................

112
(cont'd)
Radiator Coolant .............................88

Radio ................................................47

Rear View Mirrors ..........................29
Rear Window Defogger ..................28
Reminder Lights
..........................See "Warning lights"ProCarManuals.comMain Menu t s

Index (cont'd)

Replacement

Air Filter .....................................94
Bulbs........................................ 103

Engine Oil ...................................84

Fuel Filter ...................................96
Fuses .......................................101Oil Filter
......................................84

Radiator Coolant .......................90
Spark Plugs...............................92

Tires.........................................107
Wiper Blades .............................93Retractable Headlights I
f the Retractable Headlights
do not operate ...................123
Rust Prevention.........................111
Safety Items ...................................63
Seat Belt Reminder Light and
Beeper ..................................... .21

Seat Belts
Anchor Points ...........................16
Buckling the FrontSeat Belts .............................10
Buckling the Rear Seat Belts............................12
Child Restraint......................14

Cleaning .....................................17

Warning Light and Warning Beeper ...................13
Inspection ..................................17
Lap/Shoulder Belts ...................10
Pregnant Women ......................16
Reminder Light ..........................20
Replacement .............................17
Seats
Driver's Lumbar Support ...........7
Driver's Side Support..............7
Front Seat ....................................5

Head Restraints ...........................8

Shift Lever Position Indicator........20
Shifting

Automatic..................................67
5-Speed......................................65

Spare Tire

Changing a Flat Tire................116

COMPACT Spare Tire ...........114
Specifications .........................125
Spark Plugs...................................92
Specifications...............................125Speedometer ..................................
20

Starting the Engine .........................61

Steering Anti-theft Column Lock ...........
58Four Wheel Steering............59
Power Steerin g
.........................97
Tilt Steering ........................26
Stereo Sound System
Operation...................................47

Stuck Car ..............................122
Sunroof

If the Sunroof Won't

Close .....................................54

Maintenance...........................54
Operation ........................ 53

Sunshade.......................................
53

Tachometer.............................20

Temperature Gauge
,
Coolant

....................................................20

Thermostat...................................90
Tilt Steering.....................................26
Tire
Air Pressure ............................105

Balancing ................................106

Chains...................................106
Changing a Fla
t Tire................118

COMPACT Spare .................114
DOT Tir
e
Quality Grades........128
Inflation Pressures ..................105

Requirement ..................................128

Rotation ...................................
106

Snow Tires ........................ 105

Spare Tire................................114

Specification ....................... .
126

To Get In/Out of Rear Seat..............6
Tools ..............................................
116

Towing...........................................121
Towing a Traile
r ..............................
71
Transmission

Identification
Number............127

Oil/Fluid......................................86

Shifting the Automatic.............67

Shifting the Manual...................65

Capacity ...................................125ProCarManuals.comMain Menu t s