Acura Automobiles: 2017 Acura MDX Press Kit

Two Available Drive Systems

• Front-wheel drive
• Available Super Handling All-Wheel Drive System™ (SH-AWD®) with dynamic torque vectoring capability

Engine Architecture and Features

Engine Block and Crankshaft
With its 60-degree V-angle, the MDX’s V-6 engine is inherently smooth and has compact overall dimensions that allow efficient packaging within the vehicle. The V-6 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 V-6 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. Plateau honing of the cylinder lining further reduces friction between the piston skirts and the cylinder walls by creating an ultra-smooth surface. This two-stage machining process uses two grinding processes instead of the more conventional single-stage honing process. Plateau honing also enhances the long-term wear characteristics of the engine.

Pistons/Connecting Rods
Designed with “cavity-shaped” crowns, the MDX engine’s pistons help maintain stable combustion and contribute to stratified-charge 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 crankshaft connecting rods are “crack separated” to create a lighter and stronger rod with an optimally fitted bearing cap.

Cylinder Heads/Valvetrain
Like other Acura V-6 powerplants (with the exception of the NSX), the MDX 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 “tumble port” 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.

i-VTEC with 2-Stage Variable Cylinder Management™ (VCM®)
The MDX SOHC V-6 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 5,350 rpm, the i-VTEC system transitions to a high-lift, long-duration intake cam profile for superior high-rpm engine power.

VCM Operation
To help improve the fuel efficiency, Acura’s Variable Cylinder Management (VCM) is used. The VTEC system combines with Active Control engine Mounts (ACM) to allow the VCM system to operate with three cylinders in a wide range of situations to maximize fuel efficiency and lower 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. The spark plugs continue to fire in inactive cylinders to minimize plug temperature loss and prevent fouling induced from incomplete combustion during cylinder re-activation.

The system is electronically controlled, and uses special integrated spool valves in the cylinder heads. Based on commands from the system’s Electronic Control Unit, the spool valves selectively direct oil pressure to the rocker arms for specific cylinders. This oil pressure in turn drives synchronizing pistons that connect and disconnect the rocker arms.

The VCM system monitors throttle position, vehicle speed, engine speed, automatic-transmission gear selection and other factors to determine the correct cylinder activation scheme for the operating conditions. In addition, the system determines whether engine oil pressure is suitable for VCM switching and whether catalytic-converter temperature will remain in the proper range. To further smooth the transition of activating or deactivating cylinders, the system adjusts ignition timing and throttle position and turns the torque converter lock-up on and off. As a result, the transition between 3- and 6-cylinder modes is effectively unnoticeable to the driver.

Drive-by-Wire Throttle System
The MDX’s 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 underhood 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.

Acura’s drive-by-wire throttle system establishes the current driving conditions by monitoring throttle pedal position, throttle valve position, engine speed (rpm) and road speed. This information is used to define the throttle control sensitivity that gives the MDX’s throttle pedal a predictable and responsive feel that meets driver expectations.

There are two different throttle profiles available in the MDX: (1) when the Integrated Dynamics System (IDS) is in the Normal or Comfort setting, the transmission is in “D” (Drive) the drive-by-wire system uses the normal profile; (2) when the Sport mode is selected, the system switches to a more aggressive throttle map to enhance responsiveness.

Direct Injection System
The MDX’s V-6 engine 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.

The multi-hole injectors can create the ideal stoichiometric fuel/air mixture in the cylinders for good emissions control. Theoretically, a stoichiometric mixture has just enough air to completely burn the available fuel. Based on the operating conditions, the direct-injection system alters its function for best performance. Upon cold engine startup, fuel is injected into the cylinders on the compression stroke. This creates a weak stratified charge effect that improves engine start-up and reduces exhaust emissions before a normal operating temperature is reached.

Once the engine is fully warmed up for maximum power and fuel efficiency, fuel is injected during the intake stroke. This helps create a more homogeneous fuel/air mix in the cylinder that is aided by the high-tumble intake port design. This improves volumetric efficiency, and the cooling effect of the incoming fuel improves anti-knock performance.

Direct Ignition and Detonation/Knock Control
The MDX’s Electronic Control Unit (ECU) monitors engine functions to determine the best ignition spark timing. Two 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. The 3.5-liter V-6 has an ignition coil unit for each cylinder that is positioned above each spark plug’s access bore.

Idle-Stop System
To help improve fuel efficiency, the MDX with Advance Package is equipped with Idle-Stop capability. When the system is enabled by the driver and certain operating conditions are met, the Idle-Stop system will automatically shut off the engine when the vehicle comes to a stop. The engine is automatically restarted when the driver releases the brake pedal after a stop.

The system is engineered to operate smoothly and seamlessly. When stopped, a special cold storage evaporator in the air conditioning system helps maintain a comfortable cabin temperature even in warm weather. The MDX ‘s active engine mounts help smooth the restart. Idle-Stop operation is fully integrated into the operation of the MDX ‘s Brake Hold system and its Adaptive Cruise Control (ACC) system.

The Idle-Stop feature can be turned on/off via a button on the center console, located at the near of the electronic gear selector array. The system will automatically turn itself off in certain circumstances, including:

• If the driver’s seatbelt is not fastened
• If the engine coolant and/or transmission fluid temperature is too high or low
• If the vehicle comes to a stop again before vehicle speed reaches 3 mph
• If the transmission is in a position other than “D”
• If the battery state of charge is low, or the battery temperature is below 14°F
• If the climate control system is on and the outside temperature is below -4°F
• If the rear HVAC fan is set to maximum speed

Close-Coupled Catalysts
The exhaust manifolds of the 3.5-liter V-6 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 two 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. Downstream of the close-coupled catalytic converters, a hydroformed 2-into-1 collector pipe carries exhaust gases to a secondary, underfloor catalytic converter.

Emissions Control
The 2017 MDX’s 3.5-liter V-6 engine meets EPA Tier 3/Bin 125 and CARB LEV III ULEV-125 emissions standards and is certified to this level of emissions performance for 150,000 miles. A number of advanced technologies are factors in the emissions performance. The cylinder head-mounted, close-coupled catalytic converters allow for quicker light off 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.

The MDX’s V-6 engine features 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.

To further improve emissions compliance, the 3.5-liter V-6 makes use of an after-cat exhaust gas recirculation (EGR) system that allows cleaner, cooler EGR gas to be fed back into the intake system to reduce pumping losses for better fuel efficiency.

Noise Vibration Control
With its 60-degree V-angle and compact, rigid and lightweight die-cast aluminum cylinder block assembly, the 3.5-liter V-6 powerplant is exceptionally smooth during operation. Other factors that help reduce engine noise and vibration are a rigid forged-steel crankshaft, die-cast accessory mounts, and a stiff cast-aluminum oil pan that reduces cylinder block flex.

Active Control Engine Mounts and Active Sound Control
A 28-volt Active Control Engine Mount system (ACM) is used to minimize the effects of engine vibration as the VCM system switches between three- and six-cylinder operation. The 28-volt ACM is a key factor in the VCM’s broad range of operation in the MDX. 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 MDX an Active Sound Control (ASC) system further mitigates low frequencies that can occur during three-cylinder operation.

There are two different Active Sound Control profiles available in the MDX. When the Integrated Dynamics System is in the Normal or Comfort setting, the ASC is tuned for maximum interior quietness. When Sport mode is selected, the ASC allows a more aggressive interior engine sound.

100,000+/- Mile Tune-up Intervals
The  3.5-liter V-6 requires 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, replacement of the camshaft timing belt, and the installation of new spark plugs.

Battery Management System
The Battery Management System (BMS) is designed to increase the overall service life of the battery, reduce the chance of a dead battery and help improve fuel efficiency. Should the owner accidentally leave the headlights on or fail to fully close a door causing an interior light to remain on, the BMS will automatically terminate power delivery after a set period of time to prevent the battery from being drained of power. As a result of the discharge protection afforded by the BMS, the battery should always have enough reserve capacity left to start the engine.

The MDX engine makes use of a powerful 130-amp alternator that charges in two different ranges — a low 12-volt range and a high 14-volt range. By controlling the alternator charge voltage range, BMS works to keep the battery in a specific charge range, which can extend the service life of the battery by more than 25 percent. With BMS keeping the battery in a specific charge range, the alternator can run more often in the low range, which generates less drag on the engine resulting in improved fuel efficiency. Application of numerous electrical power reducing items (such as the use of efficient LED lighting and a special humidity control system that has an automatic air conditioning “off” function) allows the BMS to operate the alternator even more frequently in the more efficient low charge mode.

Maintenance Minder™ System
To eliminate unnecessary service stops while ensuring that the vehicle is properly maintained, the MDX has a Maintenance Minder™ system that continually monitors the vehicle’s operating condition. When maintenance is required, the driver is alerted via a message on the Multi-Information Display (MID).

The Maintenance Minder™ system monitors operating conditions such as oil and coolant temperature along with engine speed to determine the proper service intervals. Depending on operating conditions, oil change intervals can be extended to a maximum of 10,000 miles, potentially sparing the owner considerable expense and inconvenience over the life of the vehicle. The owner-resettable system monitors 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. To mitigate driver distraction, maintenance alerts are presented on the MID only when the ignition is first turned on, not while driving.

Sequential SportShift 9-Speed Automatic Transmission
All MDX models are equipped with a 9-speed automatic transmission featuring Sequential SportShift. The traditional console-mounted shift lever is replaced with 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. A steering wheel-mounted paddle shifter system lets the driver take manual control of transmission gear selection.

Cooperative Transmission Control
Both shift performance and smoothness are improved by cooperative control between the Drive-by-Wire throttle system and the 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
The MDX transmission can be operated in two different fully automatic modes that are controlled by the D/S selector button. In Drive (D) mode, the transmission combines fuel efficiency with smooth operation and responsive power when needed. In S mode, more aggressive shift mapping that puts the emphasis on performance-oriented driving, with higher engine rpm for greater acceleration and response.

Smart Transmission Logic
The transmission incorporates 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.

While ascending or descending hills, Grade Logic Control alters the transmission’s shift schedule to reduce shift frequency and improve speed control. The transmission ECU continually measures throttle position, vehicle speed and acceleration/deceleration to determine when the vehicle is on a hill. The shift schedule is then adjusted — 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. Shift Hold Control leaves the chassis undisturbed by eliminating excess shifting and ensures that power will be immediately available (without a downshift) at the corner exit. Cornering G Shift Control monitors the vehicle lateral acceleration to determine when the MDX is turning. When the system detects sufficient cornering speed, it will suppress any unwanted upshifts. This prevents the transmission from upshifting during a corner, which could upset the chassis balance thus requiring downshifting again at the corner exit when the throttle is applied.

Paddle Shifter Operation in Drive and Mode
While in Drive mode, 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 Drive S Mode
When the transmission is set to Drive S mode, a pull on the racing-inspired paddle shifters (mounted on the steering wheel) places the transmission in fully manual mode until another mode of operation is selected. A digital display in the instrument cluster indicates the selected gear.

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.

Drivetrain Architecture and Features

Front Wheel Drive
The MDX offers standard front wheel drive. With its efficient design and light weight, the MDX front wheel drive system makes a significant contribution to overall fuel efficiency. With EPA fuel economy ratings of 20/27/23 (city/highway/combined), the front-wheel drive MDX with Idle Stop has a 1-mpg advantage over its SH-AWD counterpart in the city, on the highway, and in the combined ratings.

Super-Handling All-Wheel Drive (SH-AWD)
The MDX is available with Acura’s acclaimed Super Handling All-Wheel Drive (SH-AWD), which progressively distributes optimum torque not only between the front and rear axles, but also between the left and right rear wheels. The system is complemented by Agile Handling Assist which employs the anti-lock brake system to individually brake either the left or right front wheel to reduce yaw delay (the period between the steering wheel input and the rotation of the body) to improve corner traceability and balance. See Chassis section for more information.

The benefits of the SH-AWD® system 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 uses torque vectoring to create 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 traction and control.

Electronic Controls and Parameters
The SH-AWD system works in cooperation with the MDX’s Vehicle Stability Assist™ (VSA®) system and Agile Handling Assist to optimize torque distribution for superior handling and traction utilization. The Electronic Control Unit (ECU) provides information on engine rpm, airflow and transmission gear-ratio selection, while the VSA ECU provides wheel-speed data. The SH-AWD ECU also monitors steering angle, lateral G-forces, vehicle yaw rate and electromagnetic clutch engagement 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 and steering angle 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 MDX 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 MDX’s lightweight SH-AWD rear drive unit is constantly overdriven by 2.7-percent. The resulting overdrive effect is regulated by hydraulically-operated left and right-side clutch packs located in the rear drive unit that independently control the power delivered to each rear wheel.  Up to 1200 N-m of torque can be delivered to either rear wheel, providing torque vectoring capability that is effective in corners with a radius of as little as 49.2 feet while also providing a limited-slip differential function when needed.

The hydraulically operated 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, which gives the system the unique ability to yaw the MDX into turns for superior handling.

In this iteration of SH-AWD, an electric motor powers a pair of hydraulic pumps – on for each clutch pack. A pair of linear solenoids controlled by the Electronic Control Unit (ECU) selectively sends pressure to the clutch packs, which in turn control the amount of power sent to each rear wheel.

Trailer Hitch and Trailer Hitch ATF Cooler Kit (Optional)
A dealer-installed receiver-style trailer hitch accommodates a variety of trailer coupler designs, and includes a draw bar, retaining pin, clip, and wiring harness with 7-pin round-style connector. Trailer hitch balls of 1-7/8 -inch or 2-inch are available separately. MDX SH-AWD models have a 5,000 lb. tow rating, when equipped with the optional Trailer Hitch ATF Cooler Kit.

Remote Engine Start with Vehicle Feedback
The MDX with Technology Package and above provides the ability to start the vehicle’s engine remotely. This enables drivers to start their MDX, thereby activating the climate control system before they get to the vehicle — perfect for hot or cold days. The remote is designed to have a range of operation of at least 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 MDX 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. The remote has three LED indicators: amber, green and red. To confirm engine start, the owner presses the LOCK button and then holds the ENGINE button for a few seconds. The amber indicator will flash while the remote communicates with the vehicle. If the engine is running, the green LED will then light for one second. If the engine is not running, the red indicator will light for one second. To verify whether the vehicle is locked, the owner presses the LOCK button once. After the amber light comes on, either the green or red LED will light for one second to indicate that the vehicle is locked or not, respectively. And if the red LED flashes three times, the vehicle is out of the remote’s range. This system can provide owners with the comfort of a pre-warmed vehicle on a cold winter morning — or a pre-cooled interior on hot days. Plus, it adds the convenience and confidence of knowing that their vehicle is securely locked, even far beyond the range of a typical remote.