ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-25
ConditionPossible CauseReferring Item
Engine hesitates
(Momentary lack of
response as
accelerator is
depressed.
Can occur at all
vehicle speeds.
Usually most severe
when first trying to
make vehicle move,
as from a stop sign.)Ignition system out of order
Spark plug faulty or plug gap out of adjustment
Leaky high-tension cord
Fuel system out of order
Fuel pressure out of specification
Engine and emission control system out of
order
Poor performance of TP sensor, ECT sensor or
MAP sensor
Faulty fuel injector
Faulty ECM (PCM)
Engine overheating
Low compression
Spark plugs in Section 6F
High-tension cords in Section 6F
Diagnostic Flow Table B-3
Trouble diagnosis in Section 6
TP sensor, ECT sensor or MAP
sensor in Section 6E1
Diagnostic Flow Table B-1
Refer to “Overheating” section
Previously outlined
Surge
(Engine power
variation under
steady throttle or
cruise.
Feels like vehicle
speeds up and down
with no change in
accelerator pedal.)Ignition system out of order
Leaky or loosely connected high-tension cord
Faulty spark plug (excess carbon deposits,
improper gap, and burned electrodes, etc.)
Fuel system out of order
Variable fuel pressure
Kinky or damaged fuel hose and lines
Faulty fuel pump (clogged fuel filter)
Engine and emission control system out of
order
Poor performance of MAP sensor
Faulty fuel injector
Faulty ECM (PCM)
High-tension cords in Section 6F
Spark plugs in Section 6F
Diagnostic Flow Table B-3
MAP sensor in Section 6E1
Diagnostic Flow Table B-1
Excessive
detonation
(Engine makes
continuously
sharp metallic
knocks that change
with throttle opening.
Sounds like pop corn
popping.)Engine overheating
Ignition system out of order
Faulty spark plug
Loose connection of high-tension cord
Fuel system out of order
Clogged fuel filter (faulty fuel pump) or fuel lines
Air inhaling from intake manifold or throttle body
gasket
Engine and emission control system out of
order
Poor performance of ECT sensor or MAP sensor
Faulty fuel injector
Faulty ECM (PCM)
Excessive combustion chamber depositsRefer to “Overheating” section
Spark plugs in Section 6F
High-tension cords in Section 6F
Diagnostic Flow Table B-1 or B-2
Trouble diagnosis in Section 6
ECT sensor or MAP sensor in
Section 6E1
Diagnostic Flow Table B-1
Piston and cylinder head cleaning
in Section 6A
6-26 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
ConditionPossible CauseReferring Item
Engine has no
powerIgnition system out of order
Faulty spark plug
Faulty ignition coil with ignitor
Leaks, loose connection or disconnection of
high-tension cord
Engine overheating
Fuel system out of order
Clogged fuel hose or pipe
Malfunctioning fuel pump
Air inhaling from intake manifold gasket or
throttle body gasket
Engine and emission control system out of
order
Maladjusted accelerator cable play
Poor performance of TP sensor, ECT sensor or
MAP sensor
Faulty fuel injector
Faulty ECM (PCM)
Low compression
Others
Dragging brakes
Slipping clutch
Spark plugs in Section 6F
Ignition coil in Section 6F
High-tension cords in Section 6F
Refer to “Overheating” section
Diagnostic Flow Table B-3 in
Section 6
Diagnostic Flow Table B-2
Accelerator cable play in Section
6E1
TP sensor, ECT sensor or MAP
sensor in Section 6E1
Diagnostic Flow Table B-1
Previously outlined
Trouble diagnosis in Section 5
Trouble diagnosis in Section 7C
ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-27
ConditionPossible CauseReferring Item
Improper engine
idling or engine
fails to idleIgnition system out of order
Faulty spark plug
Leaky or disconnected high-tension cord
Faulty ignition coil with ignitor
Fuel system out of order
Fuel pressure out of specification
Leaky manifold, throttle body, or cylinder head
gasket
Engine and emission control system out of
order
Faulty idle control system
Faulty evaporative emission control system
Faulty fuel injector
Faulty fuel injector resistor
Poor performance of ECT sensor, TP sensor or
MAP sensor
Faulty ECM (PCM)
Engine overheating
Low compression
Others
Loose connection or disconnection of vacuum
hoses
Malfunctioning PCV valve
Spark plugs in Section 6F
High-tension cords in Section 6F
Ignition coil in Section 6F
Diagnostic Flow Table B-3 in
Section 6
Diagnostic Flow Table P0505
EVAP control system in Section
6E
Diagnostic Flow Table B-1
Fuel injector resistor in Section 6E1
ECT sensor, TP sensor or MAP
sensor in Section 6E1
Refer to “Overheating” section
Previously outlined
PCV system in Section 6E1
6-28 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
ConditionPossible CauseReferring Item
Excessive
hydrocarbon (HC)
emission or carbon
monoxide (CO)Ignition system out of order
Faulty spark plug
Leaky or disconnected high-tension cord
Faulty ignition coil with ignitor
Low compression
Engine and emission control system out of
order
Lead contamination of three way catalytic
converter
Faulty evaporative emission control system
Fuel pressure out of specification
Closed loop system (A / F feed back
compensation) fails
–Faulty TP sensor
–Poor performance of ECT sensor or MAP
sensor
Faulty injector
Faulty fuel injector resistor
Faulty ECM (PCM)
Others
Engine not at normal operating temperature
Clogged air cleaner
Vacuum leaks
Spark plugs in Section 6F
High-tension cords in Section 6F
Ignition coil assembly in Section
6F
Refer to “Low compression”
section
Check for absence of filler neck
restrictor
EVAP control system in Section
6E1
Diagnostic Flow Table B-3
TP sensor in Section 6E1
ECT sensor or MAP sensor in
Section 6E1
Diagnostic Flow Table B-1
Fuel injector resistor in Section 6E1
Excessive nitrogen
oxides (NOx)
emissionIgnition system out of order
Improper ignition timing
Engine and emission control system out of
order
Lead contamination of catalytic converter
Fuel pressure out of specification
Closed loop system (A / F feed back
compensation) fails
–Faulty TP sensor
–Poor performance of ECT sensor or MAP
sensor
Faulty injector
Faulty fuel injector resistor
Faulty ECM (PCM)
See section 6F1
Check for absence of filler neck
restrictor.
Diagnostic Flow Table B-3
TP sensor in Section 6E1
ECT sensor or MAP sensor in
Section 6E1
Diagnostic Flow Table B-1
Fuel injector resistor in Section 6E1
ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-29
Ambient temp.
SCAN TOOL DATA
As the data values given below are standard values estimated on the basis of values obtained from the normally
operating vehicles by using a scan tool, use them as reference values. Even when the vehicle is in good condition,
there may be cases where the checked value does not fall within each specified data range. Therefore, judgment
as abnormal should not be made by checking with these data alone.
Also, conditions in the below table that can be checked by the scan tool are those detected by ECM (PCM) and
output from ECM (PCM) as commands and there may be cases where the engine or actuator is not operating (in
the condition) as indicated by the scan tool. Be sure to use the timing light to check the ignition timing.
NOTE:
With the generic scan tool, only star () marked data in the table below can be read.
When checking the data with the engine running at idle or racing, be sure to shift M / T gear to the neutral
gear position and A / T gear to the “Park” position and pull the parking brake fully. Also, if nothing or “no
load” is indicated, turn OFF A / C, all electric loads, P / S and all the other necessary switches.
SCAN TOOL DATAVEHICLE CONDITIONNORMAL CONDITION /
REFERENCE VALUES
FUEL SYSTEM B1 (FUEL
SYSTEM STATUS)At specified idle speed after warming upCLOSED (closed loop)
CALC LOAD
(CALCULATED LOADAt specified idle speed with no load after
warming up3 – 5%(
VALUE)At 2500 r / min with no load after warming up10 – 18%
COOLANT TEMP.
(ENGINE COOLANT
TEMP.)
At specified idle speed after warming up85 – 95C, 185 – 203F
SHORT FT BI (SHORT
TERM FUEL TRIM)At specified idle speed after warming up–20 – +20%
LONG FT BI (LONG
TERM FUEL TRIM)At specified idle speed after warming up–15 – +15%
MAP (INTAKE
MANIFOLD ABSOLUTE
PRESSURE)At specified idle speed with no load after
warming up29 – 48 kPa,
220 – 360 mmHg
ENGINE SPEEDAt idling with no load after warming upDesired idle speed
± 50 r / min
VEHICLE SPEEDAt stop0 km / h, 0 MPH
IGNITION ADVANCE
(IGNITION TIMING
ADVANCE FOR NO.1
CYLINDER)
At specified idle speed with no load after
warming up–1 – 18 BTDC
INTAKE AIR TEMP.At specified idle speed after warming up+35C (+63F)
–5C (–9F)
MAF (MASS AIR FLOW
RATE)
At specified idle speed with no load after
warming up1.0 – 3.0 gm / sec
RATE)At 2500 r / min with no load after warming up3.0 – 6.0 gm / sec
THROTTLE POS
(ABSOLUTEIgnition switch ON /Throttle valve fully closed7 – 18%
(ABSOLUTE
THROTTLE POSITION)
g
engine stoppedThrottle valve fully open70 – 90%
O2S B1 S1 (HEATED
OXYGEN SENSOR-1)At specified idle speed after warming up0.05 – 0.95 V
O2S B1 S2 (HEATED
OXYGEN SENSOR-2)When engine is running at 2000 r / min. for
3 min. or longer after warming up.0 – 0.95 V
O2S FT B1 S1At specified idle speed after warning up–20 – +20%
DIS. WITH MIL ON————
6-32 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
SCAN TOOL DATA DEFINITIONS
FUEL SYSTEM (FUEL SYSTEM STATUS)
Air / fuel ratio feedback loop status displayed as either
open or closed loop. Open indicates that ECM (PCM)
ignores feedback from the exhaust oxygen sensor.
Closed indicates final injection duration is corrected
for oxygen sensor feedback.
CALC LOAD (CALCULATED LOAD VALUE, %)
Engine load displayed as a percentage of maximum
possible load. Value is calculated mathematically us-
ing the formula: actual (current) intake air volume
maximum possible intake air volume x 100%.
COOLANT TEMP.
(ENGINE COOLANT TEMPERATURE, C, F)
It is detected by engine coolant temp. sensor
SHORT FT B1 (SHORT TERM FUEL TRIM, %)
Short term fuel trim value represents short term
corrections to the air / fuel mixture computation. A val-
ue of 0 indicates no correction, a value greater than
0 means an enrichment correction, and a value less
than 0 implies an enleanment correction.
LONG FT B1 (LONG TERM FUEL TRIM, %)
Long term fuel trim Value represents long term correc-
tions to the air / fuel mixture computation. A value of 0
indicates no correction, a value greater than 0 means
an enrichment correction, and a value less than 0 im-
plies an enleanment correction.
MAP (INTAKE MANIFOLD ABSOLUTE
PRESSURE, kPa, inHg)
It is detected by manifold absolute pressure sensor and
used (among other things) to compute engine load.
ENGINE SPEED (rpm)
It is computed by reference pulses from crankshaft
position sensor.
VEHICLE SPEED (km / h, MPH)
It is computed based on pulse signals from vehicle
speed sensor.
IGNITION ADVANCE
(IGNITION TIMING ADVANCE FOR NO.1
CYLINDER, )
Ignition timing of NO.1 cylinder is commanded by
ECM (PCM). The actual ignition timing should be
checked by using the timing light.
INTAKE AIR TEMP. (C, F)
It is detected by intake air temp. sensor and used to
determine the amount of air passing into the intake
manifold as air density varies with temperature.
MAF (MASS AIR FLOW RATE, gm / s, lb / min)
It represents total mass of air entering intake manifold
which is computed based on signals from MAP sen-
sor, IAT sensor, TP sensor, etc.
THROTTLE POS
(ABSOLUTE THROTTLE POSITION, %)
When throttle position sensor is fully closed position,
throttle opening is indicated as 0% and 100% full open
position.
OXYGEN SENSOR B1 S1
(HEATED OXYGEN SENSOR-1, V)
It indicates output voltage of HO2S-1 installed on ex-
haust manifold (pre-catalyst).
OXYGEN SENSOR B1 S2
(HEATED OXYGEN SENSOR-2, V)
It indicates output voltage of HO2S-2 installed on ex-
haust pipe (post-catalyst). It is used to detect catalyst
deterioration.
DESIRED IDLE (DESIRED IDLE SPEED, rpm)
The Desired Idle Speed is an ECM (PCM) internal pa-
rameter which indicates the ECM (PCM) requested
idle. If the engine is not running, this number is not valid.
TP SENSOR VOLT (THROTTLE POSITION
SENSOR OUTPUT VOLTAGE, V)
The Throttle Position Sensor reading provides throttle
valve opening information in the form of voltage.
INJ PULSE WIDTH
(FUEL INJECTION PULSE WIDTH, msec.)
This parameter indicates time of the injector drive
(valve opening) pulse which is output from ECM
(PCM) (but injector drive time of NO.1 cylinder for
multiport fuel injection).
IAC FLOW DUTY (IDLE AIR (SPEED) CONTROL
DUTY, %)
This parameter indicates opening of the throttle valve
in terms of percentage to opening controllable by the
ISC actuator.
TOTAL FUEL TRIM (%)
The value of Total Fuel Trim is obtained by putting val-
ues of short Term Fuel Trim and Long Term Fuel Trim
together. This value indicates how much correction is
necessary to keep the air / fuel mixture stoichiomet-
rical.
BATTERY VOLTAGE (V)
This parameter indicates battery positive voltage in-
putted from main relay to ECM (PCM).
ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-39
INFORMATION SENSORS
-1. MAP sensor
-2. TP sensor
-3. IAT sensor
-4. ECT sensor
-5. Heated oxygen sensor-1
-6. VSS
-7. Ignition coil
-8. Battery
-9. CMP sensor (in Distributor)
-10. A/C contoller (if equipped)
-11. CKP sensor
-12. CTP switch (in ISC actuator)
-13. Heated oxygen sensor-2OTHERS
A: ECM (PCM)
B: Main relay
C: EVAP canister
D: Injector resistor
E: EFE heater
F: Electric load diode CONTROL DEVICES
a: Fuel injector
b: EVAP canister purge valve
c: Fuel pump relay
d: Malfunction indicator lamp
e: ISC actuator
f: Radiator fan control relay
g: Igniter
h: EFE heater relay
i: ISC actuator relay
COMPONENT LOCATION
MAP sensorTo TP sensor
To other sensors
6-44 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
DTC P0105 MANIFOLD ABSOLUTE PRESSURE (MAP) CIRCUIT
MALFUNCTION
CIRCUIT DESCRIPTION
DTC DETECTING CONDITIONPOSSIBLE CAUSE
MAP: 5 kPa, 37.5 mmHg or less
(Low pressure – High vacuums – Low voltage)
or
MAP: 130 kPa, 975 mmHg or more
(High pressure – Low vacuums – High voltage)“G” circuit open
“Lg” circuit open or shorted to ground
“Lg / R” circuit open or shorted to ground
MAP sensor malfunction
ECM (PCM) malfunction
NOTE:
When DTC P0105, and / or P0120, P0510 are indicated together, it is possible that “Lg” circuit is open.
When DTC P0105, P0110, P0115 and / or P0120 are indicated together, it is possible that “G” circuit is
open.
DTC CONFIRMATION PROCEDURE
1) Clear DTC, start engine and keep it at idle for 1 min.
2) Select “DTC” mode on scan tool and check DTC.