1990 HONDA PRELUDE Owners Manual

Temperature

The temperature grades are A (the highest), B and C representing
the tire's resistance to the generation of heat and its ability to
dissipate heat when tested under controlled conditions on aspecified indoor laboratory test wheel. Sustained high temperature
can cause the material of the tire to degenerate and reduce tire life, and excessive temperature can lead to sudden tire failure. The grade
C corresponds to a level of performance which all passenger car
tires must meet under the Federal Motor Vehicle Safety Standard No. 109. Grades B and A represent higher levels of performance on
the laboratory test wheel than the minimum required by law.

The tire temperature grade is established for a tire that is properly
inflated and not overloaded. Excessive speed, underinflation, or

excessive loading, either separately or in combination, can cause

heat buildup and possible tire failure.ProCarManuals.comMain Menu t s

Emission Controls
Sources of Emissions
The combustion process produces carbon monoxide, oxides of nitrogen and hydrocarbons. The evaporation of fuel in the fuel tank
also produces hydrocarbons. Control of oxides of nitrogen and
hydrocarbons is very important since, under certain conditions,
when subjected to sunlight, they react to form photochemical smog. Carbon monoxide does not react to form smog, but it is toxic.
Honda Motor Co., Ltd. has developed a number of systems which
are highly effective in reducing carbon monoxide, oxides of nitrogen
and hydrocarbons.
The Clean Air Act
The Clean Air Act requires all vehicle manufacturers to explain in writing, the operation and maintenance of their emission control

systems.
Maintenance instructions are included on pages 76—81 ; the
operation of each system is explained on the following.

Replacement Parts

The emission control systems on your new Honda were designed, built and certified to conform with the Federal regulations
implementing the Clean Air Act. Honda recommends only the use of
new, genuine Honda parts or their equivalent. The use of other
replacement parts which are not of equivalent quality may impair
the effectiveness of your car's emission control systems.

Crankcase Emission Control System

To prevent crankcase emissions, your car is equipped with a Positive Crankcase Ventilation (PCV) System which routes blowby
gases from the crankcase, through the PCV valve and intake manifold, into the combustion chamber.ProCarManuals.comMain Menu t s

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

Warranty Service
Warranty The following warranties are provided with every new vehicle: 1. New Car Limited Warranty
2. Emission Control Systems Defects Warranty
3. Emissions Performance Warranty
4. Battery Limited Warranty 5. Rust Perforation Limited Warranty
6. Accessory Limited Warranty 7. Replacement Parts Limited Warranty
8. Replacement Muffler Lifetime Limited Warranty
9. Seat Belt Limited Warranty.
All warranties pertaining to your car can be found in the warranty
booklet provided with your new car except the required
maintenance schedule which is contained here in the Owner's
Manual.

If you are unable to obtain warranty service or are dissatisfied with
the warranty decision or service you received at an authorized Honda dealership, you should review the matter with that
dealership's Service Manager. This will normally resolve your problem. If it does not resolve your problem you should appeal the
decision with the owner of the dealership. Please bear in mind that
your problem will likely be resolved at the dealership, using the
dealer's facilities, equipment and personnel. So it is very important
that your initial contact be with the dealer or his management. After following these steps, if you wish to have the matterreviewed by American Honda you should contact the Automobile
Zone Office serving your area, as shown on the map on the inside of
the back cover. When contacting American Honda, please provide
the Automobile Zone Office with the following information:
Vehicle Identification Number
Servicing Dealer Name and Address
Date of Purchase
Mileage on your Car

Your Name, Address, and Phone Number
Nature of Problem

Selling Dealer

After a review of the facts, you will be advised of what can be done.ProCarManuals.comMain Menu t s

Service Manuals
A Honda Service Manual is
available for your car. It is written
for the Journeyman mechanic,
but it is simple enough for most mechanically-inclined owners to
understand.

An Electrical Troubleshooting
Manual is also available for your
car. This manual complements
the Service Manual by providing
in-depth troubleshooting

information for each electrical
circuit in your car.
You can purchase these manuals through your Honda dealer's Parts Department.ProCarManuals.comMain Menu t s