1997 Acura TL Press Kit


1997 Acura TL Press Kit


The 1997 Acura TL sedan is designed to be a touring luxury automobile and offers a sporty and more youthful alternative to traditional luxury cars. A touring automobile is one that's conceived as a long-distance runner that has the power to take its occupants across the continent effortlessly and in great style. At the same time, it has the handling response, nimbleness and quick reaction to throttle of a sporting sedan. As such, the TL provides a very high degree of luxury, comfort and interior room. The 1997 TL Series competes against other mid-luxury cars such as the Lexus ES300, Mercedes C220 and C280 and BMW 3 and 5 Series.

With its combination of luxury, performance and quality, the TL Series further strengthens Acura's position as the number one-selling luxury nameplate in the U.S. market.

Concepts and Goals

The TL is designed to provide:

  • Outstanding luxury with a full complement of comfort and convenience items as standard equipment.
  • Powerful engines that give excellent performance and response but are also efficient, durable and reliable.
  • Refined and dynamic characteristics, including excellent high-speed directional stability and accurate response to steering input.
  • An uncommonly high level of safety in terms of both active and passive safety systems.
  • Sophisticated styling that retains a sporty and luxury-oriented image.
  • A spacious interior, with ergonomically designed controls, easy-to-read instrumentation and luxury amenities designed to enhance the driving experience.


The Acura TL Series, available exclusively in a 4-door body style, comes in two variations: the 3.2TL and 2.5TL. The TL Series has the highest feature content in its class, with Automatic Climate Control and an AM/FM/ cassette/CD player standard in all models. And each model is also offered with a Premium Package that features an even higher level of standard equipment.

The luxury-oriented 3.2TL is equipped with a 3.2-liter, single-overhead-camshaft, V-6 engine equipped with four valves per cylinder, a Variable Induction System and a direct ignition system. The engine produces 200 hp and 210 lbs-ft of torque. The 3.2TL Premium Package also includes a Traction Control System (TCS) as standard equipment.

The sporty, driver-oriented 2.5TL is powered by a 2.5-liter, inline S-cylinder engine equipped with a single overhead camshaft, four valves per cylinder, Programmed Fuel Injection (PGM-FI), a dual-stage intake manifold, electronic ignition and dual knock sensors. The engine produces 176 hp and 170 lbs-ft of torque. The 2.5TL also features an innovative, electronically controlled hydraulic engine mount system which helps to reduce noise and vibration.

In keeping with the luxury aspect of the TL Series, both models feature an electronically controlled 4-speed automatic transmission as standard equipment. The automatic transmission features a Grade Logic Control System that reduces gear hunting in up- and downhill driving and provides a more refined driving experience. It also enhances engine braking in downhill driving.

Both TL Series models feature a 4-wheel independent double-wishbone suspension, 4-wheel disc brakes, a standard Acura-designed Anti-Lock Braking System (ABS) and a standard driver and front passenger air bag Supplemental Restraint System (SRS). Both models also feature the advantage of front-wheel-drive technology for excellent directional stability, superior traction on slippery road surfaces and packaging efficiencies that contribute to lighter overall weight.

Structurally, the TL represents the latest advances in rigidity, impact strength and noise isolation. In designing the chassis, the engineers used the latest structural and finite element analysis to provide a tight, quiet interior that effectively damps out road and wind noise. This rigid platform also enhances handling and bump absorption by maintaining precise suspension geometry over all road surfaces.

1997 Acura TL - Accessories

1997 Acura TL Accessories
Trunk-mounted 6-disc CD changer
Splash guards (front/rear)
Keyless entry system
Full nose mask
Half nose mask
Carpeted floor mats
Carpeted cargomat
Moonroof visor
15-inch mesh-style alloy wheels
15-inch 3-spoke alloy wheels
Fenderwell trim
Rear wing spoiler
Car cover
Ski sleeve
Gold emblem kit
Simulated wood trim kit
Wood shift knob

X = Available; * = Standard equipment; - = Not available.

The Above Accessories Are Dealer-Installed Options.

1997 Acura TL - Interior


The TL features a spacious, luxury-oriented interior designed to enhance occupant comfort and convenience. Priorities included ergonomic design for all operating systems while providing ample space for all occupants.

New for 1997, the 3.2TL adds a power moonroof and a power 4-way passenger seat as standard equipment, while the sporty 2.5TL adds subtle accents, such as a tasteful wood grain garnish to its power window switches. A variable intermittent windshield wiper feature also becomes standard equipment on all TL models in 1997.

To maximize interior space, and provide the rear occupants with ample knee and foot room, the TL was designed with a long wheelbase. A longer wheelbase allows the creation of greater cargo room and also provides a smoother ride over rough pavement. To provide easier entry and exit for the backseat occupants, the rear seats were positioned further to the rear.

The designers enhanced the feeling of spaciousness by using a horizontal styling motif that includes a sweeping, curved instrument panel and a wide wood-patterned dashboard. The sense of spaciousness is further enhanced by the low cowl height and large glass area. For added peace of mind, the TL Series features a theft-deterrent system with sensors that detect unauthorized door, trunk or hood opening. A new door lock design also deters the use of a slim jim to operate the lock from above.

In keeping with the Acura tradition of balanced performance, the cockpit is also designed to enhance the driving experience. The steering wheel is thickly padded and designed to encourage proper driving. Adding to the ambience of a driver's car is the gated transmission shifter.


Both the 3.2TL and 2.5TL Premium Package models feature a standard leather-trimmed interior. The 2.5TL features a rich cloth material for the seats and door panels. A leather-wrapped steering wheel is standard in all TL models. A leather-wrapped shift knob is standard in both 3.2.TLmodels. All models also feature a standard wood-patterned instrument panel. Both 3.2TL models also add a wood-patterned switch panel and center console as standard equipment. New for 1997, the 2.5TL also adds a special wood-grained garnish to its power window switches.

Air Conditioning And Heating

All TL models feature an Automatic Climate Control System as standard equipment. This is an all-new unit that surpasses the efficiency of any previous Acura air conditioning unit. It features greater cooling capacity for quicker interior cooldown and operates more quietly than previous units. In addition, this unit can automatically maintain the preset interior temperature to within half of a degree. The cooling system uses an environmentally safe, non-CFC refrigerant.

Dual Air Bag Supplemental Restraint System (SRS)

All TL models feature a driver and front passenger air bag Supplemental Restraint System (SRS) as standard equipment. The air bags are intended to supplement the seat belts in the event of a severe frontal collision. To ensure durability and reliability, the electrical connectors for the system are gold-plated.

The front seat belts of the TL use a direct-clamping mechanism to grip the belt near its exit from the reel. With this system, the belts effectively stay tight on the occupants, helping to reduce forward movement in the event of an impact.


The seats were designed to provide excellent fit and comfort, proper anatomical support and appropriate form-fitting to keep the driver in place during transient maneuvers. The construction methods and materials used help ensure that the seats will remain firm over the life of the vehicle. All TL models feature an 8-way power driver's seat with manually adjustable lumbar support, and the 3.2TL adds a 4-way power passenger seat as standard equipment, new for 1997. The 3.2TL Premium Package also features heated front seats.

Audio System

The standard audio system in all TL models is an 8-speaker unit with AM/FM stereo/cassette and compact disc player. Speaker selection and location were determined on the basis of the best sound propagation and imaging. There are two 6x9-inch full-range speakers on the rear deck, one 6.5inch full-range speaker mounted on each front door, two 1.5-inch tweeters on the dash top and two 2-inch midrange speakers located in the headliner.

An anti-theft feature renders the unit inoperative if it is removed from the car, until the proper five-digit security code is entered. The system also features a built-in CD control in case the owner chooses to install the optional trunk-mounted CD changer.

Theft-Deterrent System

All TL models feature a standard theft-deterrent system. It uses sensors to detect unauthorized entry and sets off the horn, flashes the lights and disables the starter system. The system monitors all doors, the hood and the trunk, and is automatically set by simply locking the doors.

Keyless Entry System

Both 3.2TL models feature a remote keyless entry system; the system is available as an option on the 2.5TL. The remote sending unit is equipped with a LOCK and an UNLOCK button. A single push of the LOCK button locks all the doors. A single push of the UNLOCK button will unlock only the driver's door and turn on the interior lights for 20 seconds. Pressing the UNLOCK button twice unlocks all the doors. The system works at a maximum distance of 10 meters.

Ashtray/Coin Box

Realizing that many drivers do not smoke, the TL is designed to give its owner a choice between using this versatile compartment as an ashtray or using it as a coin box. For non-smokers, a velvet lined insert fits into the ashtray to convert it into a coin holder.

Large Cup Holder

Perceiving a growing consumer desire, the TL features a versatile recessed cup holder. It can hold a combination of soft drink bottles and cans. A push-open lid covers the cup holder when not in use.

Large Console Box

To increase convenience, all TL models are equipped with a large console box with an integral armrest. This unit contains an upper and lower tray with a combined volume of 3.9 liters. It can hold up to nine compact discs or ten cassette tapes.

Heated Door Mirrors and Front Seats

The 3.2TL Premium Package features standard heated front seats and door mirrors. Each front seat has its own dual-position temperature control.

Trunk Pass-Through

The rear seat is equipped with a trunk pass-through access hatch that can be locked from the passenger cabin. This is convenient for storing long items in the trunk such as snow skis. For convenience, the hatch can be opened from the trunk without the use of a key.

Card Key/Ticket Holder

Located above the rearview mirror is a convenient holder for a parking card key, parking ticket or toll-road ticket.

1997 Acura TL - Chassis


The 3.2TL and 2.5TL are both equipped with a 4-wheel all-independent double-wishbone suspension with coil springs and front and rear stabilizer bars. They also have four-wheel disc brakes, standard Anti-Lock Braking System (ABS) and a speed- sensitive variable power-assisted, rotary-valve, rack-and-pinion steering system.

While the two suspension systems are similar in concept, they differ in mechanical detail and calibration. Suspension tuning for the 3.2TL is biased toward a slightly softer, more luxurious ride, while the 2.5TL is tuned for a firmer, more sports-oriented ride. The goals for both, however, were to provide the automobile with linear responsiveness, excellent directional stability, good ride quality and excellent steering feel.

The suspension engineers were aided in these goals by the favorable 60/40 front/rear weight distribution, a weight bias that was determined to be the ideal for a front-wheel-drive car.

Front Suspension

The front suspension comprises upper and lower control arms, a single-rate coil-over shock absorber mounted to the lower control arm, a radius rod and a tubular stabilizer bar. The front suspension was calibrated to minimize torque around the kingpin under cornering or bump reaction over a rough road, enhance straight-line stability by extending the caster trail, better resist crosswinds and minimize front-end dive under braking and rear-end squat under acceleration. Other priorities included reducing the tendency for the inside wheel to lift (jacking) under cornering by creating a very low roll center. On both models, the front roll center height is lower than at the rear, to enhance stability.

The 3.2TL uses an aluminum subframe to reduce weight while the 2.5TL uses a steel sub frame to mount the suspension components. The bushings that locate the subframes to the chassis are specially designed to dampen vibrations transmitted into the passenger compartment and also to minimize flex and deflection in order to maintain proper suspension geometry. The 3.2TL front stabilizer bar has a diameter of 28.6 mm with a 3.5 mm wall thickness. The 2.5TL bar has the same diameter, but with a 4.0 mm wall thickness. Both models also use hollow stabilizer bars to reduce weight.

The front shock absorbers are nitrogen gas-pressurized and fitted with a patented progressive-valve system. This valve uses special layered disk plates to control the fluid flow, rather than a fixed orifice. By using this type of valve, the suspension engineers were able to tune the damping force precisely to achieve a fine balance of handling and ride quality. In addition, a new upper shock mount was designed to minimize vibration.

Rear Suspension

The rear suspension features one upper and two lower control arms, a single-rate coil-over shock absorber mounted to the rear hub carrier, a trailing link to provide longitudinal location and toe control, and a tubular stabilizer bar.

Like the front suspension, the rear suspension is located by a subframe. In this case, the subframe in both models is made of steel. The suspension was designed to minimize bump steer and unwanted toe change under cornering, improve the anti-squat response under acceleration, and provide stable, predictable handling during transient maneuvers.

On the 3.2TL, the rear sub frame uses a special stiffening brace to increase camber rigidity and enhance stability. Both models feature a liquid-filled bushing at the pivot point of the rear suspension trailing link to reduce noise and vibration. To increase stiffness and minimize suspension deflection, a steel sleeve is used to capture the bushing in the mounting point.

The 3.2TL stabilizer bar has a diameter of 14.7 mm with a 2.6 mm wall thickness. The 2.5TL bar has a diameter of 15.9 mm with a 2.6 mm wall thickness. Like the front shock absorber, the rear uses a progressive-valve system.

Speed-Sensitive, Variable Power-Assisted, Rotary-Valve, Rack-And-Pinion Steering System

Both TL models feature an innovative, power-assisted steering gear design that is lighter and more compact than conventional power steering systems. Instead of modulating power assistance to the steering rack solely in accordance with road speed, this system varies power assist by monitoring a combination of engine rpm, road speed and the amount of torque generated between the pavement and the tire. The advantage of this system is that it exercises more precise control over the amount of power assist provided. It also provides more linear steering with regard to lateral loads encountered while cornering, reduced kickback and a reduction in operating noise. A high-capacity power steering pump assures consistent operation under even the most aggressive maneuvers. The system is tuned to provide light, effortless steering during parking, yet provides excellent road feel at higher speeds. The steering ratio for the 3.2TL is 15.7:1 and 17.5:1 for the 2.5TL.

Braking System

Braking is provided by a power-assisted, four-wheel disc braking system equipped with a dual-diaphragm master cylinder. The dual-diaphragm master cylinder is very compact, yet provides abundant boost for power assistance. Large, flex-resistant calipers help provide consistent braking performance. The front rotors are internally ventilated to aid in rapid heat dissipation. Front and rear rotor dimensions for both models are 282 mm x 23 mm and 260 mm x 9 mm, respectively. Swept area for both is 740 cm2.

Anti-Lock Braking System (ABS)

The standard Anti-Lock Braking System (ABS) features four wheel-speed sensors and three channels. The system exercises independent control over each of the front wheels and controls the rear wheels as a single unit. This is the latest generation ABS and features a number of refinements such as increased brake pedal stiffness, reduced pedal kickback when ABS is engaged, a 20% weight reduction in the ECU and wiring harness, and smaller overall size due to the integration of the modulator, accumulator and pump unit.

Wheels And Tires

To reduce unsprung weight and enhance handling, both TL models are equipped with cast-aluminum alloy wheels. The 3.2TL wheels are 6.5 inches x 15 inches, while the 2.5TL, sporting new machine-finished alloy wheels for 1997, are 6.0 inches x 15 inches.

For excellent year-round driving performance, All Season tires are fitted to both the 3.2TL and 2.5TL. The tire specification for the 3.2TL is a Michelin P205/65 R15 94V M+S All Season, while the 2.5TL is equipped with Bridgestone P205/60 R15 91H M+S All Season tires.

1997 Acura TL - Body


The body of the Acura TL has been designed and crafted to provide a spacious seating area, excellent visibility, and a quiet cabin free of road and wind noise, and to provide a rigid cell highly resistant to impact forces.

The top priority in creating the body was to impart a sense of luxury to all the mechanical and aesthetic aspects of the TL. To achieve this, the engineers examined every feature of the body and optimized it for function, ease of use, or simply a more pleasing appearance.

In keeping with the sense of luxury and refinement, the designers and stylists created a body of subtle beauty that states its case with authority but doesn't scream its purpose. The shape is classically Acura, with a low sloping hood, large greenhouse, rear quarters properly proportioned and integrated into the design of the front, and a wide, muscular stance. From the windshield back, both TL models share identical exterior body panels. They differ only in front fenders, hood and grille. The 3.2TL has a grille with vertical strakes while the 2.5TL has horizontal strakes.

Precise Fit And Finish

To enhance the look and feel of the TL, its body panels were designed to have very narrow gaps and a flush fit between adjacent body panels. The fit between glass and metal has also been kept to a minimum.

Gas-Filled Hood Dampers

To ease the opening and closing of the 3.2TL hood, the engineers chose to apply gas-filled dampers. These reduce the effort required to operate the hood by imparting the force stored in the compressed gas in the dampers. The initial force required to open the hood is reduced by approximately 50%. When the hood opens to 20 degrees it continues to open automatically.

Aluminum Bumper Beam

In order to reduce weight and facilitate recycling at the end of the vehicle's service life, body engineers specified an aluminum front bumper beam for the 2.5TL instead of a plastic beam. The aluminum beam also saves over 2 kg compared to a conventional tubular steel beam.

Plastic Moulding Door Checker

The attention to detail is evident in even small operating systems. For example, body engineers developed a new door checker system. The new system uses a plastic moulding over the door check strap. The moulding has a thicker cross section than the type previously used in Acura automobiles. In addition to enhancing the feel, the new system is also quieter in operation.


The large greenhouse contributes to a spacious feeling for the occupants and also provides excellent visibility for enhanced safety. Visibility was optimized by using slim but rigid pillars, by providing a low sloping hood and a low beltline, and by providing an ideal location for the driver's H-Point. Both TL models have a total visibility of 307 degrees.

Heat-Rejecting Glass

In order to minimize heat absorption into the passenger cabin, the TL uses newly developed heat-reflective, green-tinted glass. This glass is specially formulated to reject radiant heat by deflecting infrared and ultraviolet rays. This new type of glass performs significantly better than conventional blue-tinted glass in keeping the interior cooler.

Trunk Storage

To enhance the cargo carrying capacity, the TL features a large trunk with a low liftover height. To increase the versatility and utility of the TL, the trunk has been equipped with a storage pocket on the right side of the trunk. It can hold small items, keeping them secure while the car is in motion. A trunk pass-through hatch also allows the storage of long items such as snow skis.

1997 Acura TL - Structure


Although both TL models share almost identical dimensions and exterior body panels, they are structurally different in many crucial areas. This was largely due to the different vibration characteristics and weight balance of the two engines. As a result, the chassis was developed to optimize the rigidity and crash protection, and to minimize noise, vibration and harshness. In developing the chassis, Acura engineers used the latest Finite Element Analysis and Modeling to achieve the highest rigidity levels at the lightest possible weight. An important tool in achieving these high rigidity targets was the NASA Stress Analysis Program (NASTRAN). This tool allows chassis designers to quickly analyze and evaluate changes in a structure and find the best solution.

Unit Body Structure

The carefully designed structure is designed to help keep the center passenger section protected in the event of an impact. The center "safety cage" is specifically reinforced, and straight frame rails at the front and rear help absorb both direct and offset impact loads.

Radiused Front Frame Rails

The longitudinal engine placement has allowed the creation of a unique front frame rail design. The front frame rails are radiused as they meet the front bulkhead. This design imparts high torsional and bending rigidity to the body, and also maximizes front impact protection by dissipating the loads over a wider area and by directing the load downward toward the floorpan.

Honeycomb Floor Structure

Instead of a conventional steel stamping for the floorpan, the 2.5TL floorpan uses an I8-mm thick honeycomb sandwich. It consists of a resin-impregnated honeycomb material bonded between two layers of zinc-coated steel. This structure imparts considerable strength to the floorpan. In addition to maximizing rigidity, the honeycomb material also serves to block out noise and vibration.

Sound Insulation

While the structure effectively damps outs annoying vibrations and ensures a tight, rigid body, blocking out road noise is accomplished by using sound deadening material in strategic areas throughout the body. The amount and thickness of this material is different in each model, but a liberal amount of insulating material has been used in the front bulkhead, the floorpan, the rear bulkhead, the rear parcel shelf and the trunk to ensure a quieter passenger cabin. Sound deadening foam material is used in the C-pillars, which in testing has reduced noise in the passenger compartment by 3 decibels.

Paint Process

From bare metal body to the final inspection stage, the TL undergoes a careful 23-step, 3-coat, 3-bake painting process. TL models with pearl white exterior paint undergo a 4-coat, 4-bake process due to the unique requirements of the pearlescent pigment. The process begins by thoroughly cleaning the body of grease and other debris that might mar the final finish or prevent paint from properly bonding to the metal. The body is then put through an electrodeposition coating process, washed and then dried. At that point, the actual process of painting begins. Each successive coat of paint and the clear sealer coat is baked and washed. The final finish is glass-smooth and designed to resist fading for the life of the vehicle.

Anti-Corrosion Measures

To ensure excellent corrosion protection, over 90% of the TL outer body panels are made of double-sided galvanized steel. In fact, the only panel that is not galvanized on both sides is the roof. In addition to this, the rocker panels and other selected cavities are filled with an oil-impregnated wax material that inhibits moisture penetration and prevents rust. This, when combined with the excellent painting process, produces a corrosion-resistant body that carries a 5-year rust-through warranty.

1997 Acura TL - Powertrain


The TL Series is available with either a 3.2-liter V-6 or a 2.5-liter, inline five-cylinder, engine. The 3.2TL engine requires no scheduled tune-up for the first 100,000 miles. Like all other Acura engines, it is made of aluminum alloy and is equipped with cast-iron cylinder liners. It features a single-overhead-camshaft design, 4 valves per cylinder, a direct ignition system and a Variable Induction System. The engine also features an onboard diagnostic system (OBD-II). Peak power is 200 horsepower at 5300 rpm and torque output is 210 lbs-ft at 4500 rpm.

The engine of the 3.2TL is located longitudinally for an optimal front/rear weight distribution, higher rigidity and impact protection.

Goals for both engines included ample low-end torque for excellent driveability and plenty of high-end power for sustained cruising and passing capability.

The engine of the 2.5TL is a compact, all-aluminum, inline 5-cylinder design equipped with a single overhead camshaft, four valves per cylinder, Programmed Fuel Injection (PGM-PI) and a dual-stage intake manifold. It produces 176 hp at 6300 rpm and 170 lbs-ft of torque at a very low 3900 rpm.

The transmission for the TL Series is an electronically controlled 4-speed automatic with a Grade Logic Control System.

The longitudinal arrangement of both powertrains achieves a number of desired goals. It creates an ideal 60/40 weight distribution for excellent handling and turn-in response. Also, it allows the use of softer engine mounts, which reduce the level of noise and vibration reaching the cabin. By tilting the 2.5-liter engine 35 degrees, the engineers were also able to achieve a low hood line for maximum visibility, and a reduction of frontal area to reduce aerodynamic drag.

Engine Block/Crankshaft

Like all other Acura engines, the engine blocks of both TL models are aluminum castings with cast-in iron liners, a design known for its light weight, excellent rigidity and good long-term durability. The crankcase designs feature deep skirts and extensive webbing, substantially reducing engine noise and vibration.

Cylinder Head/Valvetrain

Both TL engines feature a 4-valve-per-cylinder valvetrain with a pent-roof combustion chamber and V-formation valves. The cylinder heads of both engines are pressure cast in aluminum for light weight, increased accuracy and improved breathing due to more precisely formed ports and runners. The combustion chambers have been designed to promote high swirl and controlled flame propagation for optimum power and efficiency. To reduce friction and mass and improve response, each pair of exhaust and intake valves are actuated by a single rocker arm. The 3.2TL engine features hydraulic valve adjusters.

Variable Induction System

For the 3.2-liter, a boost for both high-end power and low-end torque is provided by a Variable Induction System, similar to that used in the NSX. A unique two-level intake manifold - made of aluminum to save weight - provides three possible paths for air being inducted into the engine. The path is selected by three butterfly valves that are electronically controlled and actuated by intake vacuum. When the engine is running at less than 3300 rpm, air for the two banks of cylinders is strictly separated and is led through the longer of two intake paths for optimum resonance charge effect at low engine speeds. Between 3300 and 3900 rpm, the two larger butterflies open and air flows through the shorter path for best resonance effect in the midrange. Then at 3900 rpm, the third butterfly opens to provide a large plenum serving all cylinders. At this point, the resonance effect is reduced, but an inertia ram tuning effect takes over to boost high-end breathing and power output.

The 2.5 TL inline-5 cylinder engine is tilted to the right, 35 degrees from vertical. This has allowed the engineers to design a manifold with long, tuned intake runners to optimize engine breathing. Based on technology developed for the NSX, the intake manifold is a dual-stage design and increases both low-end torque and high-end horsepower.

Below 5000 rpm, the cylinder is fed by the primary runner. Above 5000 rpm, however, the engine vacuum opens a butterfly valve, allowing the passage of air through a secondary runner. This increases the volume of air entering the combustion chamber and also produces an inertia ram-tuning effect for more complete cylinder filling, increasing both horsepower and torque.

Programmed Fuel Injection (PGM-FI)

The 3.2TL and 2.5TL engines are fueled by the sequential port Programmed Fuel Injection system. The system is controlled by a microprocessor. On the basis of continuous measurements of throttle angle, crankshaft angle, coolant temperature, intake air temperature, manifold air pressure, ambient air pressure and exhaust oxygen content, it meters fuel at the correct fuel-air ratio for the best balance of driveability, power, fuel economy and exhaust emissions under each operating condition.

Knock Sensors

The 3.2TL and 2.5TL engines are equipped with dual knock sensors. If a sensor detects engine knocking, it sends a signal to the microprocessor, which in turn adjusts the ignition timing. This system allows the engines to operate safely with low octane fuel, but with a reduction in power. Premium unleaded fuel is recommended.

Variable Flow Rate Muffler

A unique variable flow rate exhaust muffler was designed to reduce noise at low engine speeds and increase engine output at higher engine speeds. When idling or at low gas flow rates, the system functions like a conventional muffler. Under high gas flow conditions, a spring-loaded valve inside the muffler opens under the force of the gas and directs exhaust gasses through a low-restriction circuit. Compared to a conventional system, this unit reduces exhaust noise by 3 decibels and increases exhaust gas flow rates by 17%. This exhaust system is used with the 3.2TL and 2.5TL engines.

Onboard Diagnostic System (OBD-II)

A new onboard diagnostic system has been incorporated into both engines. This system records and stores information on transient engine malfunctions. These can be retrieved through the diagnostic port to facilitate maintenance and repair.

Ignition System

The 3.2TL uses a direct ignition system similar to that used in Formula One racing engines and in the NSX engine. Instead of the usual single coil to distribute the timed spark to each cylinder, there is an individual coil for each spark plug. A sensor mounted behind one of the camshaft pulleys triggers the ignition. The system improves ignition reliability, helping achieve 60,000-mile intervals between spark plug replacement. The 2.5TL uses a more conventional electronically controlled ignition system. As with the 3.2TL, the ignition microprocessor automatically retards ignition timing if the knock sensors detect impending detonation.

4-Speed Automatic Transmission

The standard transmission in both TL models is an electronically controlled 4-speed automatic transmission equipped with the Grade Logic Control System. The transmission features a gated shifter to provide positive feedback to the driver that the correct gear has been selected.

In order to reduce shift shock and provide smooth gear changes, the ignition is programmed to retard momentarily during upshifts and downshifts. This reduces engine torque on the transmission's shifting elements and provides a more refined gear change.

To achieve the high smoothness goals targeted by the engineers, all shift and torque converter lockup functions are electronically controlled by means of the transmission's 32K microprocessor. This computer is linked to the 48K engine-control computer. On the basis of various operating conditions such as throttle angle, coolant temperature, vehicle speed and engine speed, the microprocessor controls shift speed and torque converter lockup.

Grade Logic Control System

The Grade Logic Control System is designed to minimize gear hunting on up- and downhill driving and to enhance engine braking on downhill driving. By using information provided by the throttle angle sensor and vehicle speed, the Grade Logic Control System can determine the slope of a hill by comparing this information with a map stored in the engine computer. Based on this information, Grade Logic Control modifies the shift schedule to hold the transmission in a lower gear for better uphill acceleration or downhill engine braking. This system reduces gear hunting and reduces shifting by as much as 50%, producing a more refined driving experience.

Hydraulic Engine Mount

To minimize engine vibration at idle and at higher engine speeds, Acura engineers developed a special electronically controlled hydraulic engine mount for the 2.5TL. The mount features an exterior valve and two chambers filled with fluid. The chambers share the same hydraulic fluid by means of two sets of orifices-one large and one small.

At idle, the large set of orifices is used, allowing fluid to flow smoothly between the chambers. Above idle speeds, a signal is sent to the valve which then engages the smaller set of orifices. Changing the orifices alters the resonant frequency of the engine mount and damps out excessive vibrations. The different vibration characteristics of the V-6 engine of the 3.2TL allows the use of a more conventional rubber engine mount.

Traction Control System (TCS)

The 3.2TL Premium Package includes a Traction Control System (TCS) designed to enhance starting performance on all road surfaces and to minimize understeer while accelerating through a turn. Using the wheel-speed sensors of the Anti-Lock Braking System (ABS), the TCS control unit measures the rotational speed of all four wheels, as well as the difference between the wheel speed and road speed. The control unit compares the signals from a steering wheel angle sensor and the yaw rate of the vehicle, calculated from the difference of rear-wheel speed. If the vehicle's actual path deviates from the path expected by the driver, considering the angle of the steering wheel, the TCS computer modulates the throttle actuator and partially closes the throttle valve. This reduces engine power and helps the vehicle maintain traction and control.

This system also comes into play on a rough road by sensing the variation in wheel speeds as they accelerate and decelerate over bumps and potholes to optimize engine output for maximum traction and acceleration.