1998 NISSAN GT-R check engine

TROUBLE DIAGNOSES t i
CONSULT (Cont'd) i
FUNCTION TEST MODE
CHECK ITEM (REMEDY)
FUNCTION
TEST
ITEM JUDGEMENT
CONDITION
lgnition switch: ON
(Engine stopped)
Displays the results of on board
diagnostic system.
SELF-DIAG
RESULTS Objective
system
--
ignition switch: ON
(Engine stopped)
Throttle position sensor circuit is
tested when throttle is opened and
closed fully. ("IDLE POSITION" is
the test item name for the vehicles
in which idle is selected by throttle
position sensor.) Harness and connector
Throttle position sensor (Closed
throttle position)
Throttle position sensor (Closed
throttle position) adjustment
Throttle linkage
Venfy operation in DATA
MONITOR mode.
Throttle
valve:
opened OFF
ON
CLOSED THROTTLE
POSl Throttle valve:
closed
lgnition switch: ON
(Engine stopped)
Throttle position sensor circuit is
tested when throttle is opened and
closed fully.
Harness and connector
Throttle position sensor
Throttle position sensor
adjustment
Throttle linkage
Verify operation in DATA
MONITOR mode.
Range
(Throttle
valve fully opened
- Throttle valve
fully closed) More
than 3.0V THROTTLE POSl
SEN CKT
lgnition switch: ON
(Engine stopped)
Neutral position switch circuit is
tested when shift lever is
manipulated.
lgnition switch: ON
(Engine stopped)
Fuel pump circuit is tested by
checking the pulsation in fuel
pressure when fuel tube is
pinched. Out of
N/P
positions OFF
Harness
and connector
Neutral position switch
Linkage adjustment
PARWNEUT POSl SW CKT
In
N/P positions
Harness and connector
Fuel pump
Fuel pump relay
Fuel filter clogging
Fuel level
There
is pressure pulsation on
the fuel feed hose.
FUEL PUMP
CIRCUIT
--
The valve timing control system is
diagnosed by checking for
operating sound of the solenoid
valve.
lgnition switch: ON
(Engine stopped)
Cooling fan circuit is tested when
cooling fan is rotated.
VALVE
TIMING
SN
CKT
Harness and connector
Cooling fan motor
Cooling fan relay
COOLING
FAN
CIRCUIT RB25DE, RB25DET
The cooling fan rotates and
stops every
3 seconds.
lgnition switch: ON -+ START
Start signal circuit is tested when
engine is started by operating the
starter. Battery voltage and water
temperature before cranking, and
average battery voltage, mass air
flow sensor output voltage and
cranking speed during cranking
are displayed.
Harness and connector
lgnition switch
START
SIGNAL
CIRCUIT Start
signal: OFF 3 ON

TROUBLE DIAGNOSES
CONSULT (Cont'd) --
CHECK ITEM (REMEDY)
FUNCTION TEST
ITEM CONDITION
JUDGEMENT
-
PWIST SIGNAL Locked position
Neutral position
Ignition
switch: ON
(Engine running)
Power steering oil pressure switch
circuit is tested when steering
wheel is rotated fully and then set
to a straight line running position. ON
OFF Harness and connector
Power steering oil pressure switch GO
CIRCUIT a Power steering oil pump
I VlAS SN CIRCUIT
0 RB20DE (UB),
RB25DE
The variable air intake system is
diagnosed by checking for opera-
tion of the actuator.
-
SWRL CONT SN
CIRCUIT
0 RB20DE (UB)
The air jet swirl control system is
diagnosed by checking for opera-
tion of the actuator.
-- -- -
a Vehicle speed sensor circuit is
tested when vehicle
is running at
a speed of 10 km/h (6 MPH) or
higher.
After warming up, idle the engine.
Ignition timing is checked by read-
ing ignition timing with a timing
light and checking whether it
agrees with specifications.
Harness and connector 877
Vehicle speed sensor
Vehicle
speed sensor input
signal is greater than 4 krnlh
(2 MPH).
VEHICLE SPEED
SEN CKT Speedometer
RS
Adjust ignition timing (by moving
camshaft position sensor or dis-
tributor)
HA
Camshaft position sensor drive
The
timing light indicates the
same value on the screen.
IGN
TIMING
ADJ
mechanism
la INJECTION SYS (Injector, fuel
pressure regulator, harness or
connector)
IGNITION SYS (Spark plug, igni-
tion coil, power transistor harness
or connector)
VACUUM SYS (Intake air leaks)
Oxygen sensor circuit
Oxygen sensor operation
Fuel pressure high or low
Mass air flow sensor
Air-fuel ratio feedback circuit
(injection system, ignition system,
vacuum system, etc.) is tested by
examining the oxygen sensor out-
put at 2,000
rpm under non-
loaded state. Oxygen sensor COUNT
More
than
5 times during 10 sec-
onds
MIXTURE
RATIO
TEST
- -- /
POWER BALANCE
Injector circuit (Injector, harness or
connector)
Ignition circuit (Spark plug, ignition
coil, power transistor harness or
connector)
Compression
Valve timing
After warming up, idle the engine.
Injector operation of each cylinder
is stopped one after another, and
resultant change in engine rotation
is examined to evaluate combus-
tion of each cylinder. (This is only
displayed for models where a
sequential
multipart fuel injection
system is used.)
D After warming up, idle the engine.
D IACV-AAC valve system is tested
by detecting change in engine
speed when IACV-AAC valve
opening is changed to
0%, 20%
and 80%. Difference
in engine speed is
greater than 25 rpm before
and after cutting off the injec-
tor of each cylinder.
Harness and connector
IACV-AAC valve
Air passage restriction between air
inlet and IACV-AAC valve
IAS (Idle adjusting screw) adjust-
ment
Difference
in engine speed is
greater than 150
rpm
between
when valve opening is at 80%
and at 20%.
IACV-AACN
SYSTEM
ECM PART NUMBER
Part number of the ECM equipped on the vehicle
can be read.
ECM: 2371 0-XXXXX
ECM-TCM: 23740-XXXXX

TROUBLE DIAGNOSES
Symptom Matrix Chart (Cont'd)
RELATION BETWEEN TROUBLE SYMPTOMS AND ENGINE MECHANICAUACCESSORIES
Malfunction of the gasoline engine will not occur when the three elements of combustion (compression
pressure, aidfuel mixture, and spark) are all normal. Though the
aidfuel mixture and the spark (ignition tim-
ing) are controlled by ECM
(.TCM) control unit, if the engine mechanical is malfunctioning,
a malfunction will
occur. (The table below shows universal cases. Some cases may not apply to the vehicle.)
Engine mechanical-related malfunction
0: High possibility 0: Medium possibility A: Low posstbility
I No I Hard
start start
I Air sucked in at oil level gauge
Air sucked in at oil filler cap
Loose air duct
(A-F/M downstream) 0 A
Misconnection of canister piping
0 A
Cracked intake manifold
0 A
Aidfuel
mix-
ture
PCV valve stuck open
Clogged fuel strainer
0 A
Clogged air cleaner element
Malfunctioning pressure regulator
A 0 0 0
Improper gasoline properties A000
EGR valve stuck open 0 0
Deposits on valve 0 0
Excessive canister purge volume
Misconnection of high-tension wire
Improperly adjusted ignition timing
Malfunctioning spark plug
High-tension wire leaks
A000
Spark Distributor cap leaks
A000
Compres-
Improper valve contact
sion pres-
. a080
sure Worn piston ring ~080
Others
Clogged catalytic converter or
exhaust system A00
Low base idle speed A
A
Foreign material (vinyl, etc.) in fuel 1 tank
Clogged radiator or capacitor
IIII
Rough idle I Poor drivability Engine stall
- - - - - - -- ': Fast
idle
Adding to the items listed above, check the following.
Wiring harness for tension Ground wires for loosenes nuids and oils for levels All connectors for connection Battery connections for loosenes and corrosion Drive belts for loosenes

TROUBLE DIAGNOSES
Symptom Matrix Chart (Cont'd)
Engine mechanical-related malfunction I Symptom characteristics and inspection hints
Airffuel
ratio becomes lean.
Air sucked in at oil filler cap
Aidfuel ratio compensation factor becomes higher.
a Intake manifold induction vacuum becomes lower.
I Cracked intake manifold I
Misconnection of canister piping Use an induction vacuum (pressure) gauge for check.
' Common to all air sucking conditions from air intake system.
-
PCV valve stuck open
I Malfunctioning pressure regulator I Various symptoms occur depending on the fuel pressure.
Abnormal noise (peep) may
be heard.
Air/fuel
mixture
Improper gasoline properties Various
symptoms occur depending on the properties.
IEGRiale
stuck open
I
Clogged fuel strainer .
Clogged air cleaner element
Deposits on valve
r
Symptoms vary with the condition how they are clogged. However, the
symptoms tend to occur when the vehicle is driving at high speed and
under high load.
I
Air/fuel ratio becomes lean. Airfluel ratio compensation factor becomes
higher.
Excessive canister purge volume
I
Engine may stall when the accelerator pedal is lightly pressed. (Especially
in summertime.)
Misconnection of high-tension wire Check if the ignition timing
is correct. 1 Improperly adjusted ignition timing 1
Malfunctioning spark plug 1
Corn- I Improper valve contact I Symptoms vary with the degree of contact and the number of cylinders. '
High-tension wire leaks
Distributor
cap leaks Symptoms
vary with the degree of leaks.
Clogged catalytic converter or exhaust sys-
l tem , In many cases, engine stalls and then restarts after a while. I
pression I
Low base idle speed
pressure
Worn piston ring I
Engine may
stall while the vehicle is decelerating or when the power '
steering load or electrical load is applied.
Symptoms vary
with the degree of wear and the number of cylinders.
I
Air conditioner load too heavy I Too much refrigerant in the system. j
Others Dragging
brake
Belt tension too high
1
I Clogged radiator or capacitor I
ArJ load too heavy
Foreign material (vinyl, etc.) in fuel tank Insufficient A/T fluid (FR model)
Symptom tends to occur when fuel level in the tank becomes lower.

TROUBLE DIAGNOSES
ldle speed adjusting screw
ECL1641 C
ldle Speed Inspection and Adjustment
ldle speed specification (After warm-up)
Engine type I RygE I RB25DE I RB25DET
Base idle speed (Pm)
(Feedback control cancelled) 600
I 1
idle speed [N or P position] (Air conditioner ON)
Ignition timing
(Feedback control cancelled) I 15*2/600
. . I I
650250 Go (700 - 900)'
CO density 0.1, max.
HC density 50, max.
': ldle speed varies with air conditioner refrigerant pressure and engine cool- "" "
ant temperature.
0
a Warm up engine to normal operating temperature.
a Connect "CONSULT' to the data link connector for CON- 87'
SULT (under the instrument lower driver panel) and turn
ignition switch ON.
Connect a tachometer to the engine speed detection ter- R8
minal.
a Check that the air conditioner load, power steering pump ~p, -4 load, and various electrical loads are not applied to the
engine. During inspection and adjustment, the
A/T selec-
tor lever must be in
"N"
or
"P"
position.
a Perform "IACV-AAC VALVE ADJn in "WORK SUPPORT EL
@ mode with CONSULS.
@ a Disconnect throttle position sensor harness connector. 8~
(Above step cancels the idle speed feedback control.)
0 Turn idle speed adjusting screw (IAS) on the AAC valve
assembly to adjust base idle speed to
600 rpm.
a Turning IAS clockwise makes base idle speed lower. Turning
IAS counterclockwise makes base idle speed higher.
a Cancel "IACV-AAC VALVE ADJ" in "WORK SUPPORT'
@ mode with CONSULT.
a Connect throttle position sensor harness connector.
a Check that the actual idle speed is 650-1-50 rpm.

TROUBLE DlAGNOSES
Ignition Timing inspection and Adjustment
lnstall a timing light to the ignition timing detection loop (blue)
A3 e Perform "IACV-AAC VALVE ADJ" in "WORK SUPPORT
mode with CONSULT.
/Ci3 Disconnect throttle position sensor harness connector.
w (Above step cancels the idle speed and ignition timing feedbacl
cont rots.)
Cancel "IACV-AAC VALVE ADJ" in "WORK SUPPORl
@ mode with CONSULT.
Connect throttle position sensor harness connector.
Race engine and check that the ignition timing advana
immediately.
With the engine idling, check that the ignition timing and bas1
idle speed is within the specification listed below.
If not within the specifications, loosen the crankshaft positio
sensor mounting bolt, turn the crankshaft position sensor
an
adjust the ignition timing to the specifications. Turning th
crankshaft position sensor counterclockwise advances th
ignition timing.
Unit: BTDCO/rpl
CAUTION:
When idle speed or ignition timing is checked and adjuste
with the throttle position sensor harness
connectc
disconnected, the self-diagnostic results of the throttle
COI
trol unit and the ABS must be erased. To erase the self-dia!
nostic
results, first turn ignition switch OFF, and then start tt
engine. Confirm that the
TCS OFF indicator lamp, 4WD indic
tor lamp, and
ABS indicator lamp are all OFF, then erase tt
self-diagnostic results. This must be done because disco
nection
of the throttle position sensor harness connectc
even for engine adjustment,
will make control units to dete
abnormal status.
RB25DE, RB25DET
15*2/600 Engine type
Ignition timing
RB20DE (VB)
1 O-e2/600

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.