1998 NISSAN GT-R fuel pressure

TROUBLE DIAGNOSES
AirIFuel Ratio Inspection
Insert probe into left exhaust pipe.
ECLl788D
L Malfunction indicator lamp
CO/HC DENSITY INSPECTION
The vehicle uses aidfuel ratio feedback system with learning func-
tion. Because wide range of compensation is available, no
CO/HC
density adjustment is necessary. G!
Warm up engine to normal operating temperature, and check
that the idle speed and the ignition timing are within the speci-
fications. Then, check
CO/HC density with COIHC meter.
CAUTION:
muffler. Therefore, insert probe of the COMC meter into the
I
RB25DET-NT model uses exhaust pressure-sensitive control
I left exhaust pipe. (under -no-load condition, exhaust gas is
emitted from the left exhaust pipe only.)
a If not within the specifications, check the airlfuel ratio feedback
@status as follows.
Select "MIR FIC MNT" in "DATA MONITOR" mode.
a Run engine at approx. 2,000 rpm or higher and check that ST
I "RICH" and "LEAN" are displayed alternately.
Turn ignition switch ON and connect terminals CHK and Rs
@ IGN on the data link connector for CONSULT (under
instrument lower driver panel) for
2 seconds or more with
a suitable harness, then disconnect them. klk~
a Warm up the engine to normal operating temperature, then run
the engine at 2,000
rpm or higher. Check that the malfunction
indicator lamp blinks at least five times in
10 seconds. La=
0 Engine speed should be increased (approx. 2,000 rpm)
before performing check, even though the
air/fuel ratio
feedback control is active during idling.
8D

TROUBLE DIAGNOSES
Fuel Pressure Inspection
Fuel pump fuse
Pressure hose
QUICK
INSPECTION
0 Turn ignition switch ON (engine not running).
Select "FUEL PUMP CIRCUIT' in "FUNCTION TEST
mode.
Pinch fuel hose with fingers and check for pulsation.
Pinch fuel hose between fuel filter and fuel gallery (fue
@ damper for RB2SDET model) with fingers while fuel puml
is operating. Hose should feel hard or pulsating.
INSPECTION USING FUEL PRESSURE GAUGE
Releasing fuel pressure
Start engine.
Select "FUEL PRESSURE RELEASE" in "WORK SUP
PORT' mode.
Touch "START' and after engine stalls, crank it two o
three times to release all fuel pressure.
Start engine and disconnect fuel pump fuse.
After engine stalls, crank it two or three times to releas
all fuel pressure.
Installing fuel pressure gauge
Connect a fuel pressure gauge between fuel filter and fue
gallery (fuel damper for
RB25DET model).
CAUTION:
When disconnecting fuel hose, use shop cloth to remove an!
fuel leaks.
Install fuel pump fuse.
Fuel pressure standard value confirmation
Start engine and check that the fuel pressure is as specified.
Fuel pressure [MPa (kg/cm2)]
At idle: 0.25 (2.5)
When vacuum hose is disconnected from pres-
sure regulator:
0.29 (3.0)
If the vehicle shows poor starting, check fuel pressure fo
approx.
5 seconds after ignition switch is turned ON (During :
sec. after ignition switch turned ON for RB25DET model).
Fuel pressure [MPa (kg/cm2)]
During 5 sec. after ignition switch turned ON:
0.29 (3.0)
When fuel pressure is NG
Too high: Malfunctioning pressure regulator, malfunction in^
fuel damper, clogged fuel return line, bent hose
Too low: Malfunctioning pressure regulator, malfunctioning fue
damper, poor fuel pump discharging, clogged fuel supply line
clogged fuel filter
CAUTION:
Also check fuel pressure at increased engine speed.

TROUBLE DIAGNOSES
ECM (-TCM) InputlOutput Signal Reference
Value (Cont'd)
d
voltages are
Terminal No. Signal name
At idle At
approx. 2,000 rpm
Approx.
12V Approx. 8V
AAC valve control
signal
[RB20DE
(UB), RB25DEl
During 5 sec. after ignition switch tumed ON: Approx. 0.25V 5 sec. after ignition switch turned ON: Battery voltage
When cranking: Approx. 0.25V At idle: Approx. 0.25V Fuel pump relay
control signal - - [RB25DETJ
During 3 sec. after ignition switch tumed ON: Approx.
0.9V
3 sec. after ignition switch tumed ON: Battery voltage
When cranking: Approx. 0.9V At idle: Approx. 0.9V
Approx. 0.9V
Air conditioner
relay control signal Air conditioner
OFF: Battery voltage
Air conditioner ON: Approx. 0.25V
MIL OFF: Battery voltage
MIL ON
RBZODE
(UB), RB25DE: Approx. 0.85V RB25DET Approx. 0.1 V
Malfunction indica-
tor lamp
lgnition switch
(START) signal
Air conditioner
switch signal Approx.
OV (Ignition
switch at START Battery voltage)
Air conditioner OFF: Approx.
4.7V Air conditioner ON: Approx. 0.1 V -
22 (CHK) Check
(Diagnosis
start)
Throttle position
sensor signal
lgnition switch
(IGN) signal CONSULT
connected: Approx. OV CONSULT not connected: Approx. OV
Accelerator pedal released: Approx. OSV Accelerator pedal fully depressed: Approx. 4.2V
(Ignition switch ON, engine not running)
lgnition switch
OFF: Approx. OV lgnition switch ON: Battery voltage Approx.
0.6 - 0.7V
24
(IGN)
Ground Approx.
OV
Power
steering oil
pressure switch
signal Steering
wheel not tumed: Approx. 4.N Steering wheel turned: Approx. OV
26
NOTE: I bove measured values obtained by analog ircuit
tester.

TCS/ABS SYSTEM
Control Unit Input/Output Signal Specifications
(Cont'd)
THRTL OPENING TAR-
GET
[%]
Display Monitor item
Motor throttle angle con-
dition
TCS
MODET3
TCS OFF LAMP Data monitor I Condition
Specifications
TCS is inoperative.
TCS is operational.
Communication line
cir-
TCS is inoperative.
Number of cylinders to cuit between
TCS/ABS
which fuel is cut off control unit and
I.z /LT TCS is operational.
ECM-TCM or ECM
GEAR
TCS
SW
TCS OFF indicator lamp
TCS OFF indicator lamp
status
1 1 lEi3FF indicator amp
TCS OFF indicator lamp
@
Check item (Reference)
SLlP LAMP
0%
0 - 100%
Gear selection
TCS OFF switch status (ONIOFF)
P/N POSITION SIGNAL Communication line cir-
@
cuit
between TCSIABS
control unit and throttle
control unit
lzc
SLlP indicator lamp is / ow
TCS OFF switch circuit ST
I
1: 1st gear 2: 2nd gear 3: 3rd gear
4: 4th gear 5: 5th gear
SLIP
indicator lamp
sta-
cuit
TCS switch ON
TCS switch OFF
PNP switch signal or
neutral position switch
signal status (ONIOFF) ON
OFF
SLlP indicator lamp is
ON.
( A/T selector position: I I
I %~hift position: I ON
ON
SLIP indicator lamp cir-
1 Other than Neutral I 1
Neutral
A/T selector position:
Other than N and P
MA' shift position:
A/T PNP switch or neu-
tral position switch circuit
OFF
'1: Tire pressure must be in accordance with specification.
'2: ABS warning lamp ON: When the ignition switch is turned ON (before starting the engine) or a malfunction is detected ABS warning lamp OFF: When the engine has started (with the system in normal condition) '3: TCS mode: 0 - 24, number of cylinders to which fuel is cut off x 4
Throttle control unit
THRTL POS SEN
Display
TH MOTOR VOLT Monitor item I Sensor
voltage (V)
Sensor voltage
(V)
Throttle valve is fully
I Approx. 0.5V closed.
Engine is idling.
I
Data monitor
Approx. 3.4V
Condition
TH OPEN CONT Specifications
Motor throttle target
angle signal (ms)
NEUT
POSl
SW
START
SIGNAL
ONIOFF TCS
is inoperative
Shift (selector) lever is in
parkheutral
position. Approx.
9 ms Check
item (Reference)
ON
1
Throttle position sensor
circuit
ONIOFF Throttle motor sensor
circuit
Communication line cir-
cuit between
TCS/ABS
control unit and throttle
control unit
Start signal circuit
ParWneutral position
switch circuit
Ignition switch
ON
I

COMBINATION METER
Diagnosis Function
(Cont'd)
METER CIRCUIT CHECK
After the segment check, press the odohrip meter switch to
verify that meters operate as shown below. (Low fuel warning
lamp goes off at this point.)
i
ELF0967D I It takes 1 minute for the meters to become stable.
DIAGNOSIS FUNCTION CANCELLATION
Turn the ignition switch ACC or OFF.
Meter-related Circuit Diagram
I I TO oil pressure W.L

COMBINATION METER
Combination Meter Input/Output Signal -
Specifications (~ont'd)
Signal name
Vehicle speed signal
(8 pulses)
Body
ground
Ground
I--
Oil pressure sensor
signal Measuring
condi!ion
operation.
Speedometer is in operation.
(Vehicle speed is approx.
40 km~h.)
Specification
Approx.
4.8V or OV
Vehicle speed is approx. 40
ELF0978D
-- - Approx. 2.4V
ON - Approx. OV
- I - I Refer to 'Component Parts Inspection" (EL-28).
J I I Voltage of the upper part of the wave form indicates the value checked with analogue circuit tester.
- Water Fuel gaugc
temperature gauge
1 Gauge indication with shorted
Gauge
indicaion with
3.4W test lamp connected
ELF0980D
Component Parts inspection
SPEEDOMETER, TACHOMETER, FUEL GAUGE AND
WATER TEMPERATURE
GAUGE
Remove each meter from the meter control unit and check the
resistance between the terminals as shown below.
Checkina terminal I
Speedometer and I Fuel gauge and water I Resistance R
B-D I B-C I Approx. 230 - 310
tachometer
A-C
OIL PRESSURE GAUGE
Disconnect oil pressure sensor connector.
Turn the ignition switch ON, and connect test lamp and lead
wire with the meter attaching screw as shown left. Check the
gauge indication.
temperature gauge
A-C
ADD~OX.
190 - 260

ENGINE MECHANICAL I RB~ODE (UB) ]
STANDARD AND REPAIR LIMIT
Firing order I 1-5-3-6-2-4
Compression pressure
MPa
(kg/cm2)/rpm
Distortion limit mm
- - -- --- - Ignition advance device
Electronically-controlled ignition advance
Engine
oil capacity
e
Spark plug standard
Limit
. Limit
of variation between cylinders
Intake manifold
Intake manifold collector
Exhaust manifold
Cylinder head
Cvlinder block
lgnition timing (during no feed back control) 1.23
(1 2%)/300
0.93 (9.5)1300
0.1 (1.0)/300
0.1 0.1
0.3
0.2
0.1
Without filter
With filter
MakerlTypeISpark
plug gap mm
Engine idling speed
W'
Idle base speed (during no feed back control)
rPm
Density of
COIHC at idling speed
Wppm Approx.
3.8
Approx. 4.2
NG WPFR5G-11 11.0
- 1
-1
650-.50
(N or P position for
A/T)
600 (N or P position for AlT)
Less than O.l/Less than 50
I New I Used I Limit
Valve
clearance
(INTIEXH)
mm
Deflection
amount of accessory V-belt
Measured with tension gauge
N (kg) Hot
engine
.
Cold engine (at ambient temperature)
Measured by pushing at 98 N (10 kg)
mm 0.36+0.062/0.53+0.062
0.31 1~,0.04/0.50i0.04
Fuel tank capacity
e
Engine coolant total capacity [with reservoir tank (max. level)] e
Thermostat opening temperature [start to open - full open]
"C
Radiator cap opening pressure
MPa (kg/cm2) Approx.
65
Approx. 9.4 82 - 95
0.06
- 0.1 0 (0.6 - 1 .O)
A/C compressor belt
Power
steering pump belt
Fan belt
Power steering pump belt
1 8-10 1 10-12 1 16
667
- 755
(68
- 77)
A/C compressor belt 1 6-8 1 7-9 / 12
Fan belt
1 3-5 1 4-6 1 7.5
559 - 637
(57
- 65)
SEC.117 Power steering
Fan belt pump be1 t
284 (29)

ENGINE MECHANICAL [ RB20DE (UB) 1
TIGHTENING TORQUE
Unit: N.m (kg-m)
Engine cover
Throttle body
Throttle position sensor
IAA unit (ACC valve)
lntake manifold collector
(upper)
Intake manifold collector
Intake manifold
Vacuum tank
Engine coolant temperature
sensor
- --
' Fuel tube
Pressure regulator
Fuel damper
Fuel hose clamp bolt
(in engine compartment)
Exhaust manifold cover
' Exhaust manifold
Oxygen sensor
Crank pulley
Cam pulley (INT)
Cam pulley
(EXH)
Timing belt cover
Timing belt rear cover
Tensioner pulley
Idler pulley
Crankshaft position sensor
' Oil pan
Oil strainer
Oil pan drain plug
ignition coil
Spark plug
* Rocker cover
Camshaft bracket
Camshaft baffle plate 5.1
- 6.5 (0.52 - 0.66)
20
- 29 (2.0 - 3.0)
1) 5.5 - 7.5 (0.56 - 0.76)
?) 5.5 - 7.5 (0.56 - 0.76)
:Tighten separately in twice.)
Cylinder head bolt
Cylinder head sub bolt
VTC solenoid
' Main bearing cap
Connecting rod nut
Flywheel and drive plate
Engine coolant drain plug
Knock sensor
Radiator mounting bracket
Auxiliary electric fan
Water pump (M6 bolt)
(M8 bolt)
(MI 0 bolt)
Water inlet
Oil pump assembly
Accelerator cable
lock nut
Fuel tank strap
Fuel sender unit lock
ring
Exhaust manifold to front
tube Front tube to catalytic
converter Catalytic converter to cent
tube Center tube to main
muffler
Alternator (main)
(stay side)
Starter motor Unit:
N-m (kg-m)
1)
29 (3.0)
2) 98 (10.0)
3)
0
(0)
4) 25
- 34 (2.5 - 3.5) GI
5) 95" - 100"
(Angle tightening)
Ec
9.0 - 12 (0.92 - 1.2)
25
- 34 (2.5 - 3.5)
49
- 59 (5.0 - 6.0) h$7'
1) 14 - 16 (1.4 - 1.6)
2) 45"
- 50"
(Angle tightening)
BW
93 - 103 (9.5 - 10.5)
34 - 44 (3.5 - 4.5)
25
- 34 (2.5 - 3.5) ST
': Tighten as specified tightening order.
1): Tighten separately in several times.