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The following are details on model year changes and specifications for the first-generation Q45. There are no guarantees on the accuracy of this information.

1990-1996 Q45 Parts Diagrams

Facts

Built in Japan.
Produced 1989-1996.

Year-to-Year Changes (Src: Consumer Guide, some changes made)

1990 Infiniti Q45: The 1990 Q45 is the most sought after by performance enthusiasts for having the tightest and most responsive steering, quickest shifting, and an actual power rating of 300-305hp. Because of a "gentleman's agreement" among Japanese manufacturers, vehicles above a certain horsepower rating were not exported. Infiniti advertised 278hp, lower than actual output. Dealers offered BBS wheels, wood trim, and window tint as an option for customers. These options were not provided by Nissan.

1991 Infiniti Q45: Two new options joined for 1991: a traction-control system, and the world's first production "Full-Active Suspension (FAS)" In that latter setup, computer-controlled hydraulic actuators at each wheel generate forces in response to signals from 10 sensors to counteract body lean, nose lift and nose dive, and fore/aft pitch on wavy surfaces.

1992 Infiniti Q45: Cars with the Full-Active Suspension were now named "Q45A." In response to customer complaints, steering became  lighter and shifts became smoother.

1993 Infiniti Q45: Monotone interiors replaced the former 2 tones, and steering wheels and other items adopted color-keying. All Q45s from here onward start off the line in first gear. Formerly, they started in second for smoother takeoffs.

1994 Infiniti Q45: The '94 Q45 arrived in spring 1993, adding a passenger-side airbag. The restyled front end featured a chrome grille and fog lamps. All Q45s now had front seatbelt pretensioners, softer leather seats, and wood inlays. Interiors adopted a friendlier layout with natural earth tones and factory wood trim around the shifter console. Side bolstering was reduced for comfort, and the seat bottoms widened to better accommodate larger drivers. Suspension bushings were softened for an easier and smoother ride. This is the last year for optional HICAS four-wheel steering, used to improve handling at highway speeds. Transmission cooling was significantly improved in response to to early failures in previous models. Thicker windows reduced road noise, making the 1994-1996 Q45 one of the quietest luxury cars sold in the United States. Air conditioning in 1994 began using the environmentally friendly R134a refrigerant, with additional condenser fans to make up for 134's reduced effectiveness. The piepan-style wheels in 1994 were replaced with turbine-style wheels with long spokes.

1995 Infiniti Q45: New alloy wheels. In late 1994, the one-touch sunroof open feature apparently disappeared. This is the last year for the Q45a with fully active height-adjustable suspension.

1996 Infiniti Q45: V8 engines deleted variable valve timing to meet new US emissions standards. Power was still advertised as 278hp, but now reflected actual output. ODB II was introduced, making diagnostics a bit easier. This year some leather interior pieces were replaced with vinyl. Metal handles were replaced with plastic. The headliner material also changed, possibly in late 1995. Due to financial difficulties, Nissan was forced to take these measures on the interior, but the 96 Q45 is among the most reliable and easiest to diagnose of the G50 series, as well as the most environmentally friendly on emissions.

1997 Infiniti Q45: The second-generaion Q45, originally based on the JDM short-wheelbase Nissan President, was replaced by the less powerful but lighter Nissan Cima, using a 4.1L 266hp V8 (VH41DE). Performance was much improved over the heavy 1996 model, the interior had more room, the ride was more compliant, but handling suffered. The analog clock disappeared but returned in later years. The original Nissan President was sold in Japan from 1990-2002.

Dimensions (Src: NICO)

Infiniti Q45 4-door sedan
Wheelbase, in. 113.4
Overall Length, in. 199.8
Overall Width, in. 71.9
Overall Height, in. 56.3
Curb Weight, lbs. 4039
Cargo Volume, cu. ft. 14.8
Standard Payload, lbs. --
Fuel Capacity, gals. 22.5
Seating Capacity 5
Front Head Room, in. 38.2
Max. Front Leg Room, in. 43.9
Rear Head Room, in. 36.3
Min. Rear Leg Room, in. 32.0

Powertrain

Engine:
90-96 4.5L DOHC 32v V8 (VH45DE)
4494 cc
274 ci
93x82.7 mm
10.2:1 compression
HP: 278 at 6000 rpm*
Torque: 292 lb-ft at 4000 rpm

Transmissions:
90-93
RE4R03A 51x65 transmission
4 speed auto
Gear Ratio
1st 2.784:1
2nd 1.544:1
3rd 1.000:1
4th 0.694:1
R200V viscous limited slip differential
Final Drive Ratio: 3.538:1

94-96
RE4R03A 51x79 transmission
4 speed auto
Gear Ratio
1st 2.569:1
2nd 1.479:1
3rd 1.000:1
4th 0.694:1
R200V viscous limited slip differential
Final Drive Ratio: 3.538:1
*Due to a limitation set by a Japanese manufacturer's agreement, the power and torque are greater than advertised, estimated at 300-305hp.

Fuel Consumption

EPA MPG City: 17
EPA MPG Highway: 22

Technical Reference Specifications (Src: "vududoc" on NICO)

1990-1996 Q45

Engine
Oil SAE 10W-30 (API SG, SH & Energy Conserving II) With Oil Filter 6 3/8 qt Without Oil Filter 5 7/8 qt
Please see the engine oil guide for other reccommendations.

Tune up
Spark Plugs (Platinum)
Standard Type PFR5G-11
Cold Type PFR6G-11 PFR7G-11
Ignition Timing 15 2 BTDC
Base Idle speed 600 25 rpm
Curb Idle (target) 650 50 rpm
Idle Mixture Ratio Less than 8 % CO

Throttle Position Sensor
T/P Closed Approx. 0.6 k
T/P Open Approx. 5 k
Idle position voltage 0.35 - 0.65V
Closed T/P Sw On rpm 810 150 rpm

Radiator Fill
Coolant Type Ethylene Glycol
Coolant Capacity 10 7/8 qt
Reservoir Tank 3/4 qt

Compression Test
Standard 185 psi
Minimum 142 psi
Diff Between Cyl. 14 psi

Fuel System
Fuel Pump Pressure @ Idle
Vacuum applied at fuel pressure regulator 34 psi
Vacuum released at fuel pressure regulator 43 psi
Recommended Fuel 91 Octane
Fuel Pump 0.2 - 5
Fuel Injector 10 - 14

Sensors
Ft/Rr O2 Sen Heaters
2.3 - 4.3
Crank Position Sensor
68 F (20C) 470 - 570
Mass Air Flow Sensor
Supply Volt. 11 - 14 V
Output Volt 1 - 1.7 V
Mass Air Flow
At Idle 3.0 - 6.0 gm/sec
2500 rpm 12.9 - 25.3 gm/sec
Coolant Temp Sensor
14 F (-10C) 7 - 11.4 k
68F (20C) 2.1 - 2.9 k
122F (50C) 0.68 - 1.00 k
194F (90C) 0.236 - 0.260 k
IACV-AAC Valve
Approx. 10
EGR Temp Sensor
32F (0C) 7.9 - 9.7 m
122F (50C) 0.57 - 0.70 m
212F (100C) 0.08 - 0.010 m
Fuel Tank Temp Sensor
68F (20C) 2.3 - 2.7 k
122F (50C) 0.79 - 0.90 k
Intake Air Temp Sensor
68F (20C) 2.1 - 2.9 k
176F (80C) 0.27 - 0.38 k

Electrical Ignition System
Firing Order
1-8-7-3-6-5-4-2
Ignition Coil
Primary Voltage 12V
Primary Approx. 0.7
Secondary Approx. 8 k
Battery Specs.
Type 95D31R
Capacity 12V / 80 AH
Discharge Amp 622 A
Alternator Type LR1110-701
Nom. Rated Out 12v / 110 A
Reg. Volt 14.1 - 14.7 V
Hot Output amp
More than 34 A / 1300 rpm
More than 82 A / 2500 rpm
More than 105 A / 5000 rpm

EPA Mileage Estimate
(city/highway) 17/22

Front Wheel Alignment

Toe-in
Range
Total toe-in (A-B) 0.0 - 0.08 in (0 - 2 mm)
Total toe-in angle (left + right)0 - 0.17 (0 - 11)
Nominal
Total toe-in (A-B) 0.04 in (1 mm)
Total toe-in angle (left + right)0.08 (5)

Range Nominal Front Wheel Turning Angle (full turn)
In/Wheel Range 35.50 - 39.50 38.50(3830) (3530 - 3930)
Out/Wheel Nominal 32

Camber
Range -1.58 to 0.08 -0.83 (-050) (-135 to 005)
Lt/Rt Difference 0.75 (45)

Caster
Range 5.75 - 7.25 6.50 (630)(545 - 715)
Lt/Rt Difference 0.75(45)

Kingpin Inclination
Range 12.00 - 13.50 12.75 (1245) (1200 - 1330)

Rear Wheel Alignment

Toe-in
Range
Total toe-in (A-B) 0.0 - 0.08 in (0 - 2 mm)
Nominal
Total toe-in (A-B) 0.04 in (1 mm)

Total toe-in angle
(left + right) 0.00- 0.17(0-10) 0.08 (5)

Camber
Range -1.58 to -0.08 -0.83 (-050) (-135 to -005)
W/Lug Nut Torque 72-87 ft/lb (10-12 kg/m)

Brake System

Brake Model Code Front Disc Brake Rear Disc Brake CL28VF AD11B
Brake Fluid DOT 3 (Recommended)
Master Cyl. Bore Dia. 1 in (25.4 mm)

Front Disc Brake
Cylinder Bore Dia.
1.685 in (42.8 mm)
Brake Pad Dimensions
Length 5.0 in (127 mm)
Width 0.433 in (11.0 mm)
Thickness 0.433 in (11.0 mm)
Brake Pad Wear Limit
Min. Thickness 0.374 in (9.5 mm)
Brake Rotor Dimensions
Outer Diameter 11.02 in (280 mm)
Standard Thickness 1.10 in (28.0 mm)
Brake Rotor Repair/Wear Limits
Max. Runout 0.0028 in (0.07 mm)
Min. Thickness 1.024 in (26.0 mm)
Max. Thickness Variation
(at least 8 positions) 0.0004 in (0.01 mm) Rear Disc Brake
Cylinder Bore Dia
1.50 in (38.2 mm)
Brake Pad Dimensions
Length 3.835 in (97.4 mm)
Width 1.335 in (33.9 mm)
Thickness 0.39 in (10.0 mm)
Brake Pad Wear Limit
Min. Thickness 0.059 in (1.5 mm)
Brake Rotor Dimensions
Outer Diameter 11.50 in (292 mm)
Standard Thickness 0.35 in (9.0 mm)
Brake Rotor Repair/Wear Limits
Max. Runout 0.0028 in (0.07 mm)
Min. Thickness 0.31 in (8.0 mm)
Max. Thickness Variation
(at least 8 positions) 0.0008 in (0.02 mm))

Brake Pedal Dimen.
Free Height 'H' 7.24 - 7.64 in (184 - 194 mm)
Depressed Height 'D' 3.94 - 4.33 in (100 - 110 mm)
Pedal Free Play 'A' 0.039 - 0.118 in (1.0 - 3.0 mm)
Switch Clearance 'C' 0.012 - 0.039 in (0.3 - 1.0 mm)

Brake Booster Model M215T
Output Rod Length 0.4045 - 0.4144 in (10.275 - 10.525 mm)
Clevis Length Approx. 5.51 in (140 mm)

Parking Drum Brake DS17HD
Inside Diameter 6.77 in(172 mm)
Brake Shoe Dimension
Length 6.07 in(154.1 mm)
Width 0.984 in (25.0 mm)
Thickness 0.118 in(3.0 mm)
Parking Drum Brake Repair/Wear Limit
Max Inside Diameter 6.81 in (173.0 mm)
Shoe Minimum Thk. 0.059 in (1.5 mm)
Parking Brake Control Number of Notches 5 - 6

ABS Wheel Sensor
Clearance Frt 0.0083- 0.028 in (0.21 - 0.71 mm)
Clearance Rr 0.0138 - 0.0246 in (0.35 - 0.625 mm)
Resistance 0.8 - 1.2 k Wheel Lug Nut 72-87 ft lb (10-12 kg-m)

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