1998 NISSAN GT-R torque

ENGINE AND EMISSION CONTROL OVERALL SYSTEM
A 1 System Description
The engine control system, which performs various controls such
as the fuel injection control and ignition timing control with a single
control unit, has been adopted.
Diagnostic system applicable to
CONSULT has been adopted for
easier inspection, service, and trouble diagnostic operations.
Description of Engine Control
I
Description \,
Performs optimum fuel injection for every operation condition for
improved exhaust performance and response.
Adopts
SOFlS (Sophisticated and Optimized Fuel Injection System)
control for optimized fuel injection.
Adopts
airbuel ratio feedback
learning control that performs
com-
0
pensation of airfiuel ratio for improved drivability when the system is
in a transitional condiiion due to sudden change in
airfiuel ratro.
Uses an ignition timing map stored in the control unit to perform
controls so that the optimum ignition timing is obtained for every
operating condition.
Performs knock control, in which the ignition timing is advancedl
retarded according to the presence of knocking, so that the
opti- 0
mum i nition timing is obtained for every operating condition and
type
oPfue1.
Performs feedback control to obtain the target idle speed for various
conditions, such as during warm-up or when the air conditioner is
actuated, via the
AAC valve that adjusts the intake air amount when
O
the throttle valve is fully closed.
Turns the fuel pump relay OWOFF according to the engine speed
Fuel
injection control
Ignition timing control
Idle
speed
control
Fuel pump drive signal. In RB25DET model, FPCM (Fuel Pump Control Modulatoi) control O
has been adopted for reduced idle noise.
Heated oxygen sensor
heater control
Air conditioner cut control
Promotes warm-up of the heated oxygen sensor for improved air1
fuel ratio feedback function. 0
Tums the air conditioner relay OFF at starting or during acceleration to reduce the engine load. 0 -- Auxiliary electric fan con-
trol
Engine,
M, TCS,ABS integrated control
Tums the auxiliary electric fan relay ONIOFF according to the - engine coolant temperature signal and air conditioner signal.
Reduces engine toque during gearshift or when TCS (Traction
Control System) is being operated via a multiplex communication
lino 0
- -
Variable valve timing con-
trol According to the engine speed and load, controls the cam phase by
hydraulic pressure to change intake valve
open/close timing for
Increased engine torque at low and middle speeds and for
enhanced
out~ut.
I o I
Canister purge control air
intake valve control
Air
jet swirl control Performs duty
control of the canister purge air according to various ooeratina conditions.
0 -r-~ e-- ---
-
Controls the intake air passage in the intake manifold collector to
increase engine torque at low and middle speeds and to enhance
output. 0
According to operation conditions, turns the air jet swirl control sole-
noid valve ONIOFF to openlclose the air jet swirl control valve
for 0
pressure control
stable combustion.
Tums the Turbo pressure control solenoid valve ONIOFF according - to operation conditions.
Ensures the vehicle's safe operation and enables the vehicle
to be
Fail-safe and backup con-
trols
Diagnostic system driven
in an emergency when any of the system major components
(microcomputer in the control unit, engine coolant temperature
0
sensor, etc.) fails.
For easier trouble diagnosis, self-diagnostic system is adopted and
the existing diagnostic system is modified so that CONSULT can be
0 used.

TROUBLE DIAGNOSES
Symptom Matrix Chart (Cont'd)
Sensor-related problems I Symptom characteristics and ins~ection hints
Open Engine
will not start when either REF signal circuit or POS signal circuit is open.
Neither fuel system nor ignition system outputs control signals.
Crankshaft position sensor
(POS, REF) Instanta-
neous break Symptoms
vary with the break time and the vehicle's driving conditions. Light
shock or surging will occur while the vehicle is being driven, and the engine will
stall at idle speed.
Ring gear crankshaft position
sensor
[RB20DE
(UB)]
Signal
Mass air flow sensor Open
Open
High output
Low output I Aidfuel
ratio becomes lean. Dirty hot wire or air entering the system could be the
cause. No
airfluel ratio compensation
is carried out during lean bum status. Drivability
may be affected.
Enters fail-safe mode. Driving under
2,400 rpm is allowed.
Airlfuel
ratio becomes rich. Black smoke may be noted. Poor contact at the
ground could be the cause.
Engine coolant temperature sen-
sor Open
Open
Opedshort
High resis-
tance
Low resis-
tance
Opedshort
Heated oxygen sensor
I
Airlfuel ratio becomes over-rich.
Same symptom as when signal wire is open.
Enters fail-safe mode. Malfunction indicator lamp comes ON. Ordinary driving is
allowed. Problems tend to occur when engine is cold or engine coolant tempera-
ture
is high.
Detects low engine coolant temperature. Problems tend to occur after engine
warm-up.
Detects high engine coolant temperature. Problems tend to occur when engine is
cold.
Base
aidfuel ratio is used.
lgnition timing is retarded within the knock control range. Lack of power may be
OpedShort
I noted.
Knock sensor lgnition
timing is retarded within the knock control range. Lack of power may be
High
Output
(noted.
Low output
1 lgnition timing may not be retarded when knock is detected.
Vehicle speed sensor
Throttle position sensor
Opedshort
Opedshort
Unstable out-
put
Poor adjust-
ment
Open
Turbo pressure sensor
(TE) Fuel
cut time becomes-shorter, or no fuel cut is observed.
Base idle speed is used. Fuel injection is not increased during acceleration.
AIT shift point changes for AfF vehicles.
Unnecessary cut-in fuel injection could be the cause. Poor contact at the ground
or control unit could be the cause.
ldle judgment is "OFF while idling. Condition returns
normal by turning the igni-
tion switch ON and OFF repeatedly.
Turbo pressure is judged zero. No remarkable malfunction will be detected.
Refrigerant pressure is judged high. ldle speed remains high while the air condi-
tioner is ON.
Refrigerant pressure sensor
Short Refrigerant pressure
is judged low. ldle speed remains low while the air condi-
tioner is ON.
lgnition switch (IGN)
lgnition switch (START)
Air conditioner switch Open
Engine
will not start because neither fuel system nor ignition system outputs con-
trol signals.
Engine starts in normal condition. Engine may not start when temperature is
extremefy
low.
Air conditioner will not operate. No other malfunction will be noted.
Park/neutral
position switch is judged "OFF. Target engine speed for cold engine
in
N or P position is reduced.
ParWneutral position switch is judged
"0N"I Fast Jdle is effective when the engine
is cold and the gear is in other than N and P posrtlons. Vehrcle excessrvely
creeps.
Open
Open
Parklneutral
position
switch
Short
Power steering oil pressure
switch Open
Engine may
stall when the steering wheel is turned while the vehicle is standstill
and the accelerator pedal is lightly pressed, or when the steering wheel is turned
Electrical load switch Short
Open
Open/short
Multiplex communication line
- -- during deceleration. '
Power steering switch is judged 'ON." Value will be compensated constantly.
Idle speed drops so that the engine can stall when electrical load is applied.
Torque reduction control is not performed. Therefore,
shift shock becomes
greater.
- -- -- -- -- Engine will not start because neither fuel system nor ignition system outputs con-
trol signals.
Open
Control unit power supply
- -- - - --- - - - - - O~edshort I Same symptoms as when sensor harness is open.
Sensor ground -- - Poor contact
Water intru-
sion - -- - - - - - -- -- In case of poor contact, the connector fitting may be loose. In case of water
intrusion, the engine stalls and become inoperative for a while. The engine may restart soon in some cases.
Control unit
and connector

TROUBLE DIAGNOSES
Symptom Matrix Chart (Cont'd)
An open circuit causes no fuel injection to the corresponding cylinder, and the heated oxygen sensor output becomes lean. When the open circuits are
observed at all cylinders, the engine will not start.
Actuator-related malfunction
Injector Symptom
characteristics and inspection hints
Drive
circuit
lgnition signal
(POW&
transistor
drive
siqnal)
(open
Injection Open
Short
Fuel pump relay
1 Open 1 Engine will not start. In case of instantaneous break, surging may occur.
A
short circuit causes continuous fuel injection to the corresponding cylinder, and
over-rich airlfuel ratio and misfire will be noted. When the short circuits are
observed at all cylinders, the engine will not start.
Foreign
material
Clogs
L
Foreign
material causes continuous fuel injection to the corresponding cylinder.
Symptoms vary with the condition how the injection port is clogged.
Aidfuel ratio
compensation factor becomes larger.
(1 10 to 125%)
Canister purge control valve Ignition primary
signal (Power
transistor ground)
Auxiliary electric fan relay
[RB25DE, RB25DETI
1 Short
Open
Open -
Open
Open
Leaks
Open
Open
lgnition coil
AAC valve
The valve purges constantly. In summertime, engine may stall at idle speed due
i to rich aidfuel ratio. In wintertime, various malfunctions may occur due to lean
airlfuel ratio.
An open circuit causes no fuel injection to the corresponding cylinder, and the '
heated oxygen sensor output becomes lean. When the open circuits are observed at all cylinders, the engine will not start. In case of instantaneous break, symptoms vary with the break time and the
vehicle's driving conditions. Light shock or surging will occur while the vehicle
is being driven.
The engine will stall when break time is long.
AAC valve is fully closed. Symptoms vary with the base engine speed. When it is
too low, engine may stall while the vehicle is decelerating or when the power
steering load or electrical load is applied.
Power
supply
s~de
primary
Second-
arY side
Power
supply
Drive
circuit
Open Open Auxiliary
electric fan will not operate even after warm-up is completed.
The valve
will not purge. Gasoline smell may be noted when the weather is hot.
Variable valve timing control
solenoid valve
Variable air intake control sole-
noid valve (NA)
Air jet swirl control solenoid
valve
[RB20DE
(UB)]
Injector ground (Total ground) lnstanta- Symptoms vary
with the break time and the vehicle's driving conditions. Surging neous break or engine stall may occur when the instantaneous break occurred during fuel
I I injection. I
Open
, Open
Short
Turbo pressure control solenoid
valve (TIC) Valve
timing not switched.
Variable air intake valve opens, and torque in low speed range is reduced.
Variable air intake valve closes, and torque in high speed range is reduced.
Open
Short Air jet
swirl control valve remains closed.
Air jet swirl control valve remains open.
Open
Open Swing valve opens earlier, and
maximum turbo pressure is reduced.
Engine will not start
because the injectors do not operate.

TROUBLE DIAGNOSES
Stall Test (Cont'd)
JUDGEMENT OF STALL SPEED
5. Depress accelerator pedal gradually while depressing brake
pedal.
6. Read stall speed quickly, and immediately release accelerator
pedal.
CAUTION: Do not
depress accelerator pedal for more than 5 seconds
when testing.
7. Move selector lever to "N" position.
8. Cool down fluid.
CAUTION:
Run engine at idle
for at least one minute.
Specification:
RB20DE 2,300 - 2,500 rpm
RB25DE 2,350 - 2,550 rpm
RB25DET 2,920 - 3,170 rpm
7 Lever position
Stall
speed status Possible causes
Forward
clutch
Forward one-way clutch
Low one-way clutch
Engine and torque converter one-way clutch
7-
0
Line pressure circuit (line pressure drop), forward clutch, low one-way clutch
and forward one-way clutch
Line pressure circuit (line pressure drop), reverse clutch and forward clutch
Forward clutch, low one-way clutch, forward one-way clutch, reverse clutch
and forward clutch
Line pressure circuit (line pressure drop), forward clutch, low one-way clutch,
forward one-way clutch, reverse clutch and
forward clutch
Clutches and brake are normal except high clutch, brake band, and overrun
It
I
0
0 0 Low & reverse brake
Reverse clutch
0: Within stall speed specification
H: Higher than stall speed specification
L: Lower than stall speed specification
0 0 0 clutch. (However, status of high clutch, brake band, and overrun clutch cannc
be confirmed by stall test.)

TROUBLE
CONSU (Cont'd)
I Monitor item
Display input
signals Main
signals
-
Description Remarks
Indicates check signal (reen-
trant signal) status for TCM
control signal output.
ONIOFF
status of shift solenoid is not
changed when thermal insula-
tion or short-circuit occurs in
these valves.
Shift solenoid A SHlFT
SN A
Shift solenoid
B [ONIOFF]
OVRRUNIC SN
- [ONOFF]
Overrun
clutch solenoid
OVRRUN/C SN2
- [ONIOFF]
HOLD SW
[ONIOFFI
X
MANU MODE SW
[ONIOFFJ
NONM MODESW
[ONIOFF]
UP SW
[ONOFF]
X
DOWN SW
[ON/OFFl X
NON SHlFT SW - [ONlOFF]
Overrun
clutch solenoid
2 (Excep
RB20DE)
HOLD!SNOW
switch
A/T mode switch - SNOW mode
1 Gate side contact in mznual
mode switch
Manual
mode switch (Except
RB20DE)
- Non-gate side contact in
manual mode switch
UP (+) side contact in manual
mode switch
Non-manual
mode switch (Excepi
RB20DE)
UP switch (Except
RB20DE)
DOWN (-) side contact in
manual mode switch
DOWN
switch (Except
RB20DE)
Non-shift switch (Except
RB20DE)
Brake switch
I Stop lamp switch
BRAKE SW
[OWOFF] I
Shift solenoid A pressure detec-
tion switch
Gear position data used for
computation by TCM, is dis-
played.
Selector lever position data, A specific value used for control
used for computation by TCM, is
displayed if fail-safe is
acti-
is displayed. vated
due to error.
Vehicle speed data, used for
computation by TCM, is dis-
played.
- -- Shift solenoid valve A (P switch)
(Except
RB20DE) SHlFT
SN A
Gear position
- --- - - Selector lever position SLCT
LVR POSl
I -
VEHICLE
SPEED
[kmlh] or [mph]
I -
Vehicle speed
THROTTLE POSl
Throttle position data, used for A specific value used for control
computation by TCM, is
dis- is displayed if fail-safe is acti-
played. vated due to error.
Throttle
position
- - Control value of line pressure
solenoid valve, computed by
TCM from each input signal, is
displayed.
Control value of torque con-
verter clutch solenoid valve,
computed by TCM from each
input signal, is displayed.
Line
pressure duty LINE
PRES
DTY I
-- Torque converter clutch soienoid
valve duty TCC
SN DUTY I
Shift solenoid valve A .-control value of shift solenoid Control value
of solenoid is dis-
valve A, computed by TCM played even
if solenoid circuit is
from each input signal, is
dis- disconnected.
. - played. The
"OFF signal is displayed if
Control value of shift solenoid solenoid circuit is shorted.
Shift solenoid valve El SHIFT SN B I valve 6, computed by TCM
from each input signal, is dis-
played.
Control value of overrun clutch
solenoid valve computed by
TCM from each input signal is I OVERRUNIC SN I Overrun clutch solenoid valve
displayed.
D Control status of TCM power
>OWER
SFT
LMP
Power shift lamp
shift lamp
-- - Voltage
- Pulse
X: Applicable
-: Not applicable

TROUBLE DIAGNOSES
Symptom Chart
Sharp shock in Engine brake
applied
Shifting
Malfunctions
Slip
(Racing)
hifting
.- erator pedal
Shifting
Shifting
inspection item
Fluid level and status
Control linkage
PNP switch (short/open circuit)
Throttle ~osition sensor (installed)
I Vehicle weed sensor
I Enaine meed sensor
A/T fluid temperature sensor
Engine idle speed
Line
Dressure
Control valve assembly
Shift solenoid
A
Shift solenoid B
Line pressure solenoid
Lock-up solenoid
Overrun clutch solenoid
Accumulator N-D
Accumulator
1-2
Accumulator 2-3
Accumulator 3-4 (N-R) Ignition coil and starter motor
Overdrive control switch
I AfT mode switch (AUTO)
Torque converter
1 Oil pump
I Reverse clutch
I High clutch
I Forward clutch
I Forward one-wav clutch
I Overrun ciutch
1 Low one-wav clutch
I Low reverse brake
Brake. band (including servo)
Parking linkage

Symptom Chart (Cont'd)
Greater noise
Malfunctions
Inspection item No shifting
I Shifting I
Fluid level
and status 11
Control linkage
-
(I) C 0 .- c. .- (I) 0 a
v
-CU
n - 1
PNP switch
(shortlopen
circuit)
Throttle position sensor (installed)
2 2
Vehicle speed sensor
I Engine speed sensor -
-T
L o 1 Control valve assembly .- - -- Shift solenoid A 4 3
. ' Shift solenoid 6 4 cut I1
--, Line pressure solenoid .- 5 -t Lock-up solenoid ?
6 Overrun clutch solenoid 3
Accumulator N-D
1 Accumulator 1-2 I 1-
Accumulator 2-3
Accumulator 3-4 (N-R)
Ignition coil and starter motor
I Overdrive control switch I 1-
A/T mode switch (AUTO)
A/T mode switch (POWER) I - I Ail mode switch (SNOW) I
I Torque converter I I
1 Oil pump I I -- - - Reverse clutch 0 -
'g High clutch a 4 6
%I Forward clutch I I - .- a Forward one-way clutch -
$ Overrun clutch a, 8
Low one-way clutch
O Low reverse brake 7
Brake band (including servo) 7
Parking linkage

TROUBLE DIAGNOSES
Symptom Chart (Cont'd)
xi - - ([I C V) a, C .- cn C W
t 0 .- .L 2 a, - 8 0 ([I L 0 0 Q
& 0 a, a, Q V)
5 E .- X
i! L a
zl -I - 1 -
- 2 -
-
-
-
-
-
5 - 3 - 4 -
-
-
-
-
-
-
-
-
-
-
-
-
I1 - 0 - 6 - 7 -
-
-
-
-
9 - 8 -
-
vj c 0 .- - .- V) 0 n
Q 7J C ([I
t C .- r ([I c. V) c. 0 C V) a 0 7J 0, C .- 0 C W -
- 2 - 3 -
-
- -
-
1 -
-
-
-
- - a +- ([I a a, 2 0 c. 0 C V) a, 0 u a, - 0 2
8 - 1 -
-
-
-
-
-
-
-
2 - 3 -
-
-
-
-
-
-
-
-
-
-
- I
i
g
- 4 -
-
-
-
-
-
-
B- ; 2 to a =? - 0,
2 5.j c 2.z 2 a0 - 0- z & 5 0 gE V) V)o C 02 .s nu 5 ng %-([I C O c --t .- V) a V) r aa ([I z gz a, a- c 50 -6 s
6 $2
11
2
I
I
Malfunctions
Inspection item
I I I Fluid level and status I I Control linkage 2
PNP switch (shortfopen circuit) 1 I I I Throttle position sensor (installed) 111213
Vehicle speed sensor
214
Engine speed sensor L -
AIT fluid temperature sensor
Engine idle weed
Line pressure
Control valve assembly
Shift solenoid A 3
3
Shift solenoid B 4 4
Line pressure solenoid
Lock-up solenoid
Overrun clutch solenoid
u I I I -
Accumulator N-D I I 1 I Accumulator 1-2
Accumulator 2-3 I Accumulator 3-4 (N-R)
Ignition coil and starter motor
Overdrive control switch
Torque converter
tg Reverse clutch .- High clutch
2 Forward clutch C .- a Forward one-way clutch -.
$ Overrun clutch 0, 8
? Low one-way clutch 3= O Low reverse brake 9
Brake band (including servo)
Parking linkage