2018 TLX V6 A-Spec SH-AWD – Powertrain detail
As Acura’s top selling car, the 2018 TLX performance luxury sedan offers a range of power and drivetrain choices, with two direct-injected engines, two advanced transmissions and, in V6 powered models, available Super Handling All-Wheel Drive™ (SH-AWD®).
The TLX’s two direct injected (DI) engines combine power and efficiency. The 2.4-liter DOHC i-VTEC® 4-cylinder produces a peak 206 horsepower and 182 lb.-ft. of torque. The available 3.5-liter direct injected i-VTEC® 24-valve V6 produces a peak 290 horsepower and 267 lb.-ft. of torque. To boost fuel efficiency, Variable Cylinder Management (VCM) automatically deactivates three of the engine’s six cylinders under light engine loads. TLX SH-AWD models also add an automatic idle-stop feature to further improve fuel efficiency.
To make the most of these powerful and refined engines, the TLX features two highly advanced transmissions. 2.4-liter TLX models have an 8-Speed Dual-Clutch Transmission (8DCT), the world’s first automotive DCT with a torque converter, featuring Sequential SportShift. With its closely-spaced ratios, ultra-quick shifts and automatic downshift rev-matching, the 8DCT gives the 2.4-liter TLX an aggressively sporting feel. The torque converter provides exceptionally smooth operation in stop-and-go situations, plus it offers off-the-line torque multiplication for substantially improved initial acceleration that a DCT alone cannot equal. For 2018, the 8DCT has been updated for smoother operation.
TLX models with the 3.5-liter V6 are equipped with a 9-speed automatic transmission featuring Sequential SportShift. Retuned for 2018 for a more refined feel, the transmission is engineered to handle the V6 engine’s substantial power output, and its closely spaced gear ratios enhance both performance and fuel efficiency.
Acura’s acclaimed torque vectoring Super Handling All-Wheel Drive™ (SH-AWD®), the most sophisticated all-wheel drive system in the industry, is available exclusively with the 3.5-liter V6. SH-AWD progressively distributes torque not only between the front and rear axles, but also between the left and right rear wheels. Using torque vectoring to help turn the vehicle, SH-AWD creates a more responsive, neutral and predictable platform while providing outstanding all-weather confidence and control.
All TLX front-wheel drive models feature standard Acura Precision All-Wheel Steer™ (P-AWS), which is designed to help give the TLX greater agility and handling balance. See Chassis section for more information.
Key Powertrain Features
2.4-liter DOHC i-VTEC
- 2.4-liter, DOHC, inline-four engine produces peak output of 206 horsepower at 6,800 rpm and peak torque of 182 lb.-ft. at 4,500 rpm (both SAE net)
- i-VTEC® (intelligent Variable Valve Timing Control and Lift Electronic Control) for intake valves
- Computer-controlled Direct Injection (DI) with multi-hole fuel injectors
- 11.6:1 compression ratio
- High-strength steel crankshaft
- Drive-by-Wire™ throttle system
- Direct ignition system
- Detonation/knock control system
- Integrated Dynamics System (IDS) provides three unique drive-by-wire throttle profiles
- Maintenance Minder™ system optimizes service intervals
- 100,000 +/- miles tune-up interval
- High-flow, close-coupled next-generation precious metal catalytic converter plus under floor catalytic converter
- ULEV-3 Emissions compliant
Sequential SportShift 8-Speed Dual-Clutch Transmission (DCT) with Torque Converter and Paddle Shifters
- Retuned for 2018 for a more refined feel
- World’s first automotive DCT to be equipped with a torque converter
- Straight-gate style console-mounted shifter
- Sequential SportShift allows semi-manual operation
- Steering wheel-mounted, racing-inspired paddle shifters
- Cooperative control between Drive-by-Wire throttle system and transmission makes for quicker, smoother shifts
- Advanced shift-hold control limits up shifts during spirited driving
- Grade Logic Control System reduces gear “hunting” on steep hills
3.5-liter SOHC i-VTEC V6 with VCM
- 3.5-liter, SOHC, V6 engine produces peak output of 290 horsepower at 6,200 rpm and peak torque of 267 lb.-ft. at 4,500 rpm (both SAE net)
- i-VTEC® (intelligent Variable Valve Timing and Lift Electronic Control) for intake valves with Variable Cylinder Management™ (VCM®)
- Computer-controlled Direct Injection (DI) with multi-hole fuel injectors
- 11.5:1 compression ratio
- High-strength steel crankshaft
- Crossflow magnesium intake manifold
- Drive-by-Wire™ throttle system
- Direct ignition system
- Detonation/knock control system
- Integrated Dynamics System (IDS) provides three unique drive-by-wire profiles
- Maintenance Minder™ system optimizes service intervals
- 100,000 +/- miles tune-up interval
- High-flow, close-coupled next-generation precious metal catalytic converters plus under floor catalytic converter
- ULEV-3 Emissions compliant
Sequential SportShift 9-Speed Automatic with Paddle Shifters
- Retuned for 2018 for a more refined feel
- Electronic shift-by-wire gear selector
- Sequential SportShift automatic transmission allows semi-manual operation
- Steering wheel mounted racing-inspired paddle shifters
- Cooperative control between Drive-by-Wire throttle system and transmission makes for quicker, smoother shifts
- Advanced shift-hold control limits up shifts during spirited driving
- Grade Logic Control System reduces gear “hunting” on various road gradients
- Continuously adaptive Sport+ setting which selects shift strategies suited for aggressive driving conditions
Two Available Drive Systems
- Front-wheel drive (FWD)
- Available Super Handling All-Wheel Drive System™ (SH-AWD®) with dynamic torque vectoring capability (V6)
Engine Architecture and Features
Direct-Injected 2.4-liter Inline 4-cylinder Engine
The TLX’s direct injected (DI) 2.4-liter DOHC i-VTEC® 4-cylinder engine features a host of intelligent technology. The engine’s i-VTEC system combines VTC (Variable Timing Control), which continuously adjusts the intake camshaft phase, with Variable Valve Timing and Lift Electronic Control (VTEC), which changes valve lift, timing and duration of the intake valves. The direct injection (DI) system, dual-stage intake manifold and other technologies combine to produce 206 horsepower and 182 lb.-ft. of torque. The 4-cylinder engine meets ULEV-3 emissions standards in select states, and Federal Tier 2, Bin 5 standards.
TLX 2.4-liter 4-cylinder Powertrain
4-Cylinder Engine Block, Crankshaft and Pistons
The TLX’s 2.4-liter engine has a lightweight die-cast aluminum block with a single main-bearing cradle design that creates a rigid assembly to help minimize noise and vibration. Cast-in iron cylinder liners provide long-lasting durability. Each journal on the forged-steel crankshaft is micropolished to reduce internal friction. To improve smoothness throughout the rpm range and help lower noise levels, the engine is fitted with an internal balancer unit. Consisting of a pair of chain-driven counter-rotating shafts located in the lower block and integrated into the oil pan, the balancing system helps quell the inherent second-order harmonic vibrations that normally impact inline 4-cylinder engines.
To reduce piston-sliding friction, the cylinder bores are offset by 8.0 mm from the crankshaft. This gives the connecting rods a more favorable angle during each power stroke, which reduces side loading on the pistons and in turn, improves efficiency. The engine features a forged crankshaft for high rigidity and low friction. Lightweight pistons have a carefully optimized skirt design to minimize reciprocating weight, and reduced weight minimizes vibration and increases operating efficiency. The piston crowns are dished, to help maintain stable combustion and to optimize distribution of the stratified fuel charge from the direct injector in each cylinder. This close control over the combustion process boosts overall operating efficiency.
4-Cylinder Dual-Stage Intake Manifold
To maximize power output, the 2.4-liter engine has a dual-stage intake manifold has two different intake runner lengths that are selected based on the operating conditions. An actuator and a set of four butterfly valves control the intake runner switching process. At low engine speeds, the long runners are used to improve low-end torque. At higher engine speeds the system switches to the short intake runners for greater high rpm power. The result is intake tuning that is optimized for the engine’s entire operating range.
2.4-liter Engine Cylinder Head and Valvetrain
The lightweight cylinder head is made of pressure-cast aluminum alloy, with exhaust passages cast directly into the cylinder head. This eliminates the need for a traditional separate exhaust manifold and allows the close-coupled catalytic converter to be mounted directly to the cylinder head.
A silent-chain drives the dual overhead cams and features a double-arm tensioner design that reduces operating friction. The cam drive is designed to be maintenance free throughout the life of the engine.
To help boost fuel efficiency and power, the combustion chamber shape and valve angles have been optimized. The included valve angle is a narrow 35 degrees, which decreases the surface-to-volume ratio and helps create a flatter, more compact combustion chamber that reduces unburned hydrocarbon emissions. With this combustion chamber shape and the precise control of direct injection, the compression ratio set at 11.6:1.
The cylinder head features a “tumble port” intake design. In combination with the combustion chamber and piston crown shape, the design’s high level of airflow tumble helps create a homogenous fuel mixture for low fuel consumption and high airflow for high power output.
2.4-Liter Engine i–VTEC® Valve Control System
The TLX’s direct-injected 2.4-liter DOHC 16-valve i-VTEC® engine uses an advanced valve-control system to combine high power output with high fuel efficiency and low emissions. The system combines VTC (Variable Timing Control), which continuously adjusts the intake camshaft phase, with Variable Valve Timing and Lift Electronic Control (VTEC), which changes valve lift, timing and duration of the intake valves.
At low rpm, the VTEC intake valve timing and lift are optimized for high torque and low fuel consumption. As engine rpm builds past 4,900 rpm, the VTEC system transitions to a high-lift, long-duration intake cam profile for superior high-rpm engine power.
The “intelligent” portion of the system is its ability to continuously vary the timing of the intake cam relative to that of the exhaust camshaft. This helps boost power and also provides a smoother idle (allowing idle speed to be reduced). The intake cam timing is varied based on input from sensors that monitor rpm, timing, throttle opening, cam position and exhaust air-fuel ratio. The result is increased fuel efficiency and lower NOx emissions.
3.5-liter V6 Engine
The TLX 3.5-liter i-VTEC® V6 is closely related to the 3.5-liter V6 that powers the Acura RLX and MDX. It has a die-cast lightweight aluminum alloy block with cast-in-place iron cylinder liners, a smooth-firing 60-degree V-angle, and compact overall dimensions. The TLX powerplant combines Direct Injection with i-VTEC® and Variable Cylinder Management (VCM) to give the TLX strong fuel economy ratings and overall performance. This clean-running engine meets ULEV-3 emissions standards in select states, and Federal Tier 3, Bin 125 standards.
The aluminum-alloy 24-valve engine produces 290 horsepower at 6,200 rpm and generates 267 lb-ft of torque at 4,500 rpm.
TLX 3.5-liter V6 Powertrain
V6 Engine Block and Crankshaft
With its 60-degree V-angle, the TLX’s available V6 engine has compact overall dimensions that allow efficient packaging within the vehicle. The V6 has a die-cast lightweight aluminum alloy block with cast-in-place iron cylinder liners. Made with a centrifugal spin-casting process, the thin-wall liners are high in strength and low in porosity. The block incorporates a deep-skirt design with four bolts per bearing cap for rigid crankshaft support and minimized noise and vibration. The 3.5-liter V6 uses a high-strength steel crankshaft for minimum weight. A cooling control spacer positioned in the water jacket surrounding the cylinders helps control warm-up and operating cylinder liner temperatures to reduce friction.
V6 Pistons/Connecting Rods
Designed with “cavity-shaped” crowns, the V6 engine’s pistons help maintain stable combustion and contribute to optimized combustion. Ion-plated piston rings help reduce friction for greater operating efficiency. Heavy-duty steel connecting rods are forged in one piece and then the connecting rods are “crack separated” to create a lighter and stronger rod with an optimally fitted bearing cap.
V6 Cylinder Heads and Valvetrain
Like other Acura V6 powerplants (other than the NSX), the TLX engine’s 4-valve cylinder heads are a single-overhead-camshaft design, with the cams driven by the crankshaft via an automatically tensioned toothed belt. Made of low-pressure cast, low-porosity aluminum, each cylinder head incorporates a laminar flow intake design that improves combustion efficiency by creating a more homogeneous fuel-air mixture. An integrated exhaust manifold cast into each cylinder head reduces parts count, saves weight, improves flow and optimizes the location of the close-coupled catalyst.
V6 i-VTEC® with 2-Stage Variable Cylinder Management™ (VCM®)
The TLX SOHC V6 combines Variable Cylinder Management (VCM) with Variable Valve Timing and Lift Electronic Control (i-VTEC®), which changes the lift profile, timing and lift duration of the intake valves. A switching mechanism allows each cylinder to operate with low-rpm valve lift and duration or high-rpm lift and duration. The rear cylinder bank’s valve gear closes all intake and exhaust valves to minimize pumping losses while operating in three-cylinder mode.
The “intelligent” portion of the system is its ability to vary valve operation based on the driving situation and engine rpm. At low rpm, the i-VTEC® intake valve timing and lift are optimized (low lift, short duration) for increased torque, which allows a wide range of 3-cylinder operation. As engine rpm builds past 5,000 rpm, the i-VTEC® system transitions to a high-lift, long-duration intake cam profile for superior high-rpm engine power.
V6 VCM™ Operation — To help improve the fuel efficiency of the TLX engine, Acura’s Variable Cylinder Management™ (VCM™) is used. The system cooperates with Active Control engine Mounts (ACM) to allow the engine to operate with three cylinders in a wide range of situations to maximize fuel efficiency and reduce emissions. When greater power is needed, the system switches seamlessly to 6-cylinder operation.
During startup, aggressive acceleration, or steep ascents — any time high power output is required — the engine operates on all six cylinders. During moderate-speed cruising and at low or moderate engine loads, the system operates just the front bank of three cylinders.
The VCM system can tailor the working displacement of the engine to match the driving requirements from moment to moment. Since the system automatically closes both the intake and exhaust valves of the cylinders that are not used, pumping losses associated with intake and exhaust are eliminated and fuel efficiency gets a further boost. The system combines maximum performance and maximum fuel efficiency — two characteristics that don’t typically coexist in conventional engines.
VCM deactivates specific cylinders by using the i-VTEC (intelligent Variable Valve-Timing and Lift Electronic Control) system to close the intake and exhaust valves while the Electronic Control Unit (ECU) simultaneously cuts fuel to those cylinders.
V6 SH-AWD Idle Stop System
To help improve fuel efficiency, TLX SH-AWD models come equipped with Idle Stop. When the system is active and certain operating conditions are met, the TLX engine will automatically shut off when the vehicle comes to a stop. When the driver releases the brake pedal after a stop, the engine automatically restarts and the TLX is ready to accelerate.
V6 Active Control Engine Mounts and Active Sound Control
A powerful 28-volt Active Control Engine Mount system (ACM) is used to minimize the effects of engine vibration as the VCM system switches cylinders on and off. Sensors alert the Electronic Control Unit (ECU) to direct ACM actuators positioned at the front and rear of the engine to cancel engine vibration using a reverse-phase motion. In the cabin of the TLX, an Active Sound Control (ASC) system further mitigates low frequency noise that can occur during 3-cylinder operation.
There are two different Active Sound Control profiles available in the TLX. When the Integrated Dynamics System is in the ECON or Normal setting, the ASC is tuned for maximum interior quietness; in Sport or Sport+ mode, the ASC allows a more aggressive interior engine and exhaust note. See Interior section for more information.
Remote Engine Start
The V6 TLX with Advance Package offers the ability to start the vehicle’s engine remotely. This enables drivers to start their TLX, thereby activating the climate control system and heated/ventilated seats before they enter the vehicle — perfect for hot or cold days. The remote is designed to have a range of operation of up to 300 feet. To start the engine remotely, the owner presses the LOCK button and then holds the ENGINE button for a few seconds. When the engine is started remotely, the wipers, lighting and audio systems remain off, and the security system remains set. The engine will run for up to 10 minutes after remote starting, and then shut off automatically if the owner doesn’t reach the vehicle within that time. When the owner does get to the TLX within 10 minutes, the engine will keep running while the owner unlocks the vehicle and gets in. This system also provides feedback to the owner to confirm whether the engine is running or the vehicle is locked via the remote’s three LED indicators.
Common Engine Features
Cold-Air Induction System
To maximize power output, the TLX has a cold-air intake system that picks up air coming through the front grille area, which is typically about 5 percent cooler than the air in the hot engine compartment. Cooler intake air has greater density, which allows the Direct Injection system to add proportionately more fuel for enhanced power output.
Direct Injection System
Both 4-cylinder and V6 TLX engines feature efficient direct injection. The system features a compact, high-pressure, direct-injection pump that allows both high fuel flow and pulsation suppression, while variable pressure control optimizes injector operation. A multi-hole injector delivers fuel directly into each cylinder (not to the intake port, as in conventional port fuel injection designs), allowing for more efficient combustion and greater power output.
Drive-by-Wire™ Throttle System
The TLX Drive-by-Wire™ throttle system replaces a conventional throttle cable with smart electronics that “connect” the accelerator pedal to a throttle valve inside the throttle-body. The result is less under-hood clutter and lower weight, as well as quicker and more accurate throttle actuation. Plus, a specially programmed “gain” rate between the throttle pedal and engine offers improved drivability and optimized engine response to suit specific driving conditions.
Three different throttle profiles are available in the TLX. When the Integrated Dynamics System (IDS) is in the ECON mode, the system uses a gradual profile that encourages fuel savings. In Normal mode, the throttle profile balances economy and performance for all-around driving. When the Sport or Sport+ mode is selected, the system switches to a more aggressive throttle map to enhance responsiveness.
Direct Ignition and Detonation/Knock Control
The TLX’s Electronic Control Unit (ECU) monitors engine functions to determine the best ignition spark timing. Engine block-mounted acoustic detonation/knock sensors “listen” to the engine, and based on this input, the ECU can retard the ignition timing to prevent potentially damaging detonation. An ignition coil unit for each cylinder is positioned above each spark plug’s access bore.
Close-Coupled Catalysts
The exhaust manifolds of both TLX engines are cast directly into the aluminum cylinder heads to reduce weight, decrease parts count, and create more underhood space. The result of this casting design is that the primary catalytic converters are positioned much closer to the combustion chambers, enabling extremely rapid converter “light-off” after engine start. A significant weight savings is realized by eliminating traditional exhaust manifolds.
Emissions Control
Both 2018 TLX engines meet the tough EPA Tier 3/Bin 125 and CARB LEV III ULEV emissions standards, and are certified to this level of emissions performance for 120,000 miles. A number of advanced technologies are factors in the emissions performance. The unique cylinder head-mounted close-coupled catalytic converters light off quickly after engine start up, and a 32-bit RISC microprocessor within the Electronic Control Unit (ECU) boosts computing power to improve the precision of spark and fuel delivery.
Both engines feature Programmed Fuel Injection (PGM-FI) that continually adjusts the fuel delivery to yield the best combination of power, low fuel consumption and low emissions. Multiple sensors constantly monitor critical engine operating parameters such as intake air temperature, ambient air pressure, throttle position, intake airflow volume, intake manifold pressure, coolant temperature, exhaust-to-air ratios, as well as the position of the crankshaft and the camshafts.
Friction-Reducing Technologies
Both TLX engines make use of friction-reducing technologies designed to improve engine efficiency. The outer skirts of lightweight aluminum pistons feature a special coating that reduces overall friction as the pistons move within the cylinder bores. Plateau honing further lowers the friction level between the pistons and the cylinders by creating an ultra-smooth surface. Plateau honing is a 2-stage machining process that uses two grinding processes instead of the more conventional single honing process. This also enhances the long-term wear characteristics of the engine.
One-Touch Start System
To ensure consistent starting, the TLX has a one-touch start system that maintains starter engagement until the engine starts. Should the driver release the Start button before the engine starts, the system will start the vehicle. Simply push the Start button (with a foot on the brake pedal and the key fob in the vehicle) and the engine will automatically start up.
100,000+/- Mile Tune-up Intervals
The TLX’s engines require no scheduled maintenance for 100,000+/- miles or more, other than periodic inspections and normal fluid and filter replacements. The first tune-up includes water pump inspection, valve adjustment, installation of new spark plugs, and in V6 models, replacement of the camshaft timing belt.
Maintenance Minder™ System
To eliminate unnecessary service stops while ensuring that the vehicle is properly maintained, the TLX has an owner-resettable Maintenance Minder™ system that continually monitors the vehicle’s operating condition and all normal service parts and systems, including oil and filter, tire rotation, air-cleaner, automatic transmission fluid, spark plugs, timing belt, coolant, brake pads and more. When maintenance is required, the driver is alerted via a message on the Multi-Information Display (MID).
Sequential SportShift 8-Speed Dual-Clutch Transmission (DCT) with Torque Converter
To maximize performance and fuel efficiency, the 2.4-liter TLX has a standard 8-speed Dual-Clutch Transmission (DCT), which was the world’s first transmission of this type to be paired with a torque converter. For 2018, the transmission has been retuned for a more refined feel. In the 8-speed DCT, one clutch controls the odd gears while the other clutch controls the even gears. This arrangement allows gear changes with a much smaller interruption in power to the wheels, resulting in millisecond-quick shifts.
SportShift 8-Speed DCT with Torque Converter
Compared to a conventional manual transmission, the operation of the clutches and shifting mechanisms are electronically controlled, eliminating the need for a clutch pedal or manual shift lever. The DCT with its closely spaced ratios, ultra-quick shifts and automatic downshift rev-matching, gives the TLX 4-cylinder an exhilarating and sporty feel. The DCT transmission in the TLX also features a steering wheel-mounted paddle shifter system that lets the driver take manual control of transmission gear selection, further heightening the driving experience.
The ultra-thin torque converter complements the efficient operation of the DCT by providing exceptionally smooth operation in stop-and-go situations, plus it offers off-the-line torque multiplication for improved initial acceleration that a DCT alone can’t equal. In an aggressive standing-start launch, the torque converter substantially improves acceleration in the first 1.4 seconds, or about the first 60 feet (compared to a DCT alone).
Sequential SportShift 9-Speed Automatic Transmission
TLX V6 models are equipped with a 9-speed automatic transmission featuring Sequential SportShift. For 2018, the transmission has been retuned for a more refined feel. The transmission features a fully electronic, shift-by-wire gear selector. Park, Neutral and Drive are selected with the push of a button. Reverse is selected by pulling back a dedicated switch. Indicator lights near the buttons indicate the mode selected. As an added safety feature, if the vehicle is brought to a stop in Drive, the system will automatically select Park if the driver’s seatbelt is unbuckled and the driver’s door is opened. As with the DCT, a steering wheel-mounted paddle shifter system lets the driver take manual control of transmission gear selection.
Sequential SportShift 9-Speed AT
Common Transmission Features
Cooperative Transmission Control
Both shift performance and smoothness are improved by cooperative control between the Drive-by-Wire™ throttle system and the two available transmissions. The engine is throttled by the engine management system during upshifts and downshifts; thus the function of the engine and transmission can be closely choreographed for faster, smoother shifting. As a result, the peak g-forces (or “shift shock”) are reduced significantly during upshifts and downshifts.
Automatic Modes
Both TLX transmissions can be operated in two different, fully automatic modes, which are controlled by the Integrated Dynamics System (IDS). In Econ, Normal and Sport IDS modes, the transmission combines fuel efficiency with smooth operation and responsive power when needed. When the IDS is placed in Sport+ mode, the transmission switches to more aggressive mapping that puts the emphasis on performance-oriented driving, with higher engine rpm for greater acceleration and response.
Smart Transmission Logic
Both transmissions incorporate an advanced Grade Logic Control System, Shift Hold Control and Cornering G Shift Control — all of which reduce unwanted shifting and gear hunting. The result is smart transmission operation that optimizes fuel efficiency and keeps the transmission in the appropriate gear for driving conditions, generating excellent performance and smooth operation.
Grade Logic Control alters the transmission’s shift schedule during ascents to hold the transmission in lower gears to boost climbing power, and during descents to provide greater engine braking.
Shift Hold Control keeps the transmission in its current (lower) gear ratio during aggressive driving, as in the case of decelerating at a corner entry, leaving the chassis undisturbed by eliminating excess shifting and ensures that power will be immediately available at the corner exit.
Cornering G Shift Control monitors the vehicle lateral acceleration to suppress any unwanted upshifts which could upset the chassis balance thus requiring downshifting again when the throttle is applied at the corner exit.
Paddle Shifter Operation in Econ, Normal and Sport Integrated Dynamic System (IDS) Modes
While in Econ, Normal or Sport IDS modes, special transmission logic programming allows the use of the steering-wheel-mounted paddle shifters. When the driver operates the paddle shifters, the transmission responds to the driver’s shift command and then returns to its normal fully automatic mode if further paddle shift inputs are not made within a given time. This special logic makes it easy for the driver to command a quick downshift without leaving the convenience of Drive mode.
Paddle Shifter Operation in Sport+ Mode
When the Integrated Dynamics System is switched to the Sport+ mode, a pull on either paddle shifter places the transmission in fully manual mode until another mode of operation is selected. A digital display in the instrument cluster indicates which gear the transmission is in.
A double-kick-down feature lets the driver command a sport-minded double downshift — such as from Fifth to Third gear. By pulling on the left downshift paddle twice in rapid succession, the transmission will drop directly to the chosen lower gear ratio. The Drive-by-Wire™ throttle system also creates a “blip” of the throttle to help match gear speeds while downshifting.
To prevent harm to the powertrain when the transmission is paddle shifted by the driver (including during double-kick-down shifts), the system will inhibit potentially damaging shifts. As an added safety measure, the Electronic Control Unit (ECU) can also cut off fuel to the engine to prevent over-revving. If fuel cut-off is insufficient to prevent engine over-revving, as may be possible when the vehicle is on a steep downhill, the transmission will automatically upshift to prevent damage. On downshifts, the transmission will not execute a driver command that will over-rev the engine.
Front-Wheel Drive
The TLX offers front-wheel drive, paired with either the 4-cylinder or V6 engine. With its efficient and lightweight design, the TLX front-wheel drive system makes a significant contribution to overall fuel efficiency.
The latest version of Acura Precision All-Wheel Steer® (P-AWS) is standard on all front-wheel drive TLX models, and helps give the TLX best-in-class dynamic performance at all speeds. See Chassis section for more information.
The system is complemented by Agile Handling Assist (AHA), which selectively uses the vehicle’s brakes to improve initial turning response and overall cornering ability. AHA applies braking force to the inside wheels during high G cornering to improve corner traceability and provide a confident handling feel.
Super-Handling All-Wheel Drive™ (SH-AWD®)
Available on all V6 equipped models, the TLX SH-AWD features a hydraulically controlled iteration of Acura’s acclaimed Super Handling All-Wheel Drive system, which progressively distributes optimum torque not only between the front and rear axles, but also between the left and right rear wheels. SH-AWD is complemented by Agile Handling Assist to further improve cornering characteristics of the TLX. See Chassis section for more information.
V6 TLX with Super-Handling All-Wheel Drive™ (SH-AWD®)
The benefits of SH-AWD are superior all-weather handling and neutral, accurate steering under power that is unmatched by front-drive, rear-drive or conventional all-wheel-drive systems.
By rotating the outside rear wheel faster than the front axle while cornering, SH-AWD creates a yaw moment to help turn the vehicle through the corner — reducing understeer and improving controllability. With cornering forces more evenly distributed between front and rear tires, overall cornering power is increased — on wet or dry roads.
Vehicles with high power ratings using conventional front or rear drive systems often employ a limited-slip differential to help maintain traction when under power. By linking inside and outside drive wheels, these systems tend to resist turning and can increase understeer. Conventional AWD systems similarly work to link the inboard and outboard tires as well as the front and rear axles, which can create resistance to turning. Using torque vectoring to help turn the vehicle, SH-AWD delivers more responsive, neutral and predictable handling performance while providing outstanding all-weather handling and control.
Electronic Controls and Parameters
SH-AWD works in cooperation with Vehicle Stability Assist™ (VSA®) system and Agile Handling Assist (AHA) to optimize the TLX’s torque distribution for superior handling and traction utilization. The Electronic Control Unit (ECU) provides information on engine torque, airflow and transmission gear-ratio selection, while the VSA ECU provides wheel-speed data. The SH-AWD system’s ECU also monitors steering angle, steering angle rate of change, lateral G-forces, vehicle yaw rate and hydraulic clutch pressure for the right and left rear axle shafts. Drive torque is calculated from ECU information, and then the acceleration situation, wheel spin, lateral G-force, steering angle and steering angle rate-of-change are used to determine the front-to-rear torque distribution and the torque split between right and left rear wheels.
SH-AWD operating parameters include:
- Up to 90 percent of available torque can be transferred to the front wheels during normal cruising.
- In hard cornering and under acceleration, up to 70 percent of available torque can be directed to the rear wheels to enhance vehicle dynamics.
- Up to 100 percent of the torque sent to the rear axle can be applied to either the left or right rear wheel, depending on conditions.
SH-AWD System Layout — The TLX SH-AWD is a full-time all-wheel-drive system that requires no driver interaction or monitoring, thanks to a torque-transfer unit that is bolted directly to the front-mounted transaxle. The torque-transfer unit receives torque from a helical gear that is attached to the front differential’s ring gear, and a short horizontal shaft and hypoid gear set within the torque-transfer unit’s case send power to the rear propeller shaft, which in turn transfers power to the rear drive unit.
The TLX’s SH-AWD rear drive unit is constantly overdriven by 2.7 percent. The resulting overdrive effect is regulated by left- and right-side clutch packs (located in the rear differential) that independently control the power delivered to each rear wheel. The high overdrive percentage in the TLX means that the torque vectoring effect is pronounced and effective even in corners with a radius of as little as 49.2 feet (15 meters). This means that torque vectoring can be felt often, such as when accelerating aggressively through a standard corner. Up to 885 lb.-ft. of torque can be delivered to either rear wheel, which gives the system the unique ability to yaw the TLX into turns for superior handling.
Hydraulically operated clutch systems mounted on either side of the hypoid gear that drives the rear axles control the amount of torque sent to each rear wheel and provide a limited-slip differential function when needed. The clutches can be controlled as a pair to alter front/rear torque split or they can be controlled independently to allow 100 percent of available rear axle torque to go to just one rear wheel.
In this iteration of SH-AWD, a single electric motor powers a pair of hydraulic pumps — one for each clutch pack. An Electronic Control Unit (ECU) controlled linear solenoid valve selectively sends pressure to the clutch packs, which in turn control the amount of power sent to each rear wheel.
The clutch packs and their friction material are carefully designed to withstand the small amount of continuous slip between front and rear axles created by the 2.7 percent speed differential — all while delivering the durability expected of an Acura product.