6-24 ENGINE GENERAL INFORMATION AND DIAGNOSIS
Fig. 1 for Step 5
Fig. 2 for Step 611 Check ignition spark as follows :
1) Disconnect injector couplers.
2) Remove spark plugs and connect them to
high tension cords.
3) Ground spark plugs.
4) Crank engine and check if each spark plug
sparks.
Is it in good condition?Go to Step 12. Go to “DIAGNOSIS” in
Section 6F1.
12 Check fuel injector for operation as follows :
1) Install spark plugs and connect injector con-
nectors.
2) Using sound scope (1), check operating
sound of each injector (2) when cranking
engine. See Fig. 6.
Was injector operating sound heard from all
injectors?Go to “ENGINE DIAGNO-
SIS TABLE”.Go to “DIAG. FLOW
TABLE B-1”. Step Action Yes No
[A] : When not using SUZUKI scan tool:[A]
6-26 ENGINE GENERAL INFORMATION AND DIAGNOSIS
ENGINE DIAGNOSIS TABLE
Perform troubleshooting referring to following table when ECM has detected no DTC and no abnormality has
been found in visual inspection and engine basic inspection previously.
Condition Possible Cause Correction
Hard Starting
(Engine cranks OK) Faulty spark plug Spark plugs in Section 6F1.
Leaky high-tension cord High-tension cords in Section 6F1.
Loose connection or disconnection of high-
tension cords or lead wiresHigh-tension cords in Section 6F1.
Faulty ignition coil Ignition coil in Section 6F1.
Dirty or clogged fuel hose or pipe Diagnostic Flow Table B-3.
Malfunctioning fuel pump Diagnostic Flow Table B-3.
Air inhaling from intake manifold gasket or
throttle body gasket
Faulty idle air control system Diagnostic Flow Table B-4.
Faulty ECT sensor or MAP sensor ECT sensor or MAP sensor in Section
6E1.
Faulty ECM
Hard Starting
(Engine cranks OK) Poor spark plug tightening or faulty gasket Spark plugs in Section 6F1.
Compression leak from valve seat Valves inspection in Section 6A1.
Sticky valve stem Valves inspection in Section 6A1.
Weak or damaged valve springs Valve springs inspection in Section
6A1.
Compression leak at cylinder head gasket Cylinder head inspection in Section
6A1.
Sticking or damaged piston ring Cylinders, pistons and piston rings
inspection in Section 6A1.
Worn piston, ring or cylinder Cylinders, pistons and piston rings
inspection in Section 6A1.
Malfunctioning PCV valve PCV system in Section 6E1.
Low compression Compression check in Section 6A1.
Low oil pressure
Improper oil viscosity Engine oil and oil filter change in Sec-
tion 0B.
Malfunctioning oil pressure switch Oil pressure switch inspection in Sec-
tion 8.
Clogged oil strainer Oil pan and oil pump strainer cleaning
in Section 6A1.
Functional deterioration of oil pump Oil pump in Section 6A1.
Worn oil pump relief valve Oil pump in Section 6A1.
Excessive clearance in various sliding parts
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-27
Engine noise
Note : Before
checking mechani-
cal noise, make sure
that :
Specified spark
plug is used.
Specified fuel is
used.Improper valve lash Valve lash in Section 6A1.
Worn valve stem and guide Valves inspection in Section 6A1.
Weak or broken valve spring Valve springs inspection in Section
6A1.
Warped or bent valve Valves inspection in Section 6A1.
Worn piston, ring and cylinder bore Pistons and cylinders inspection in Sec-
tion 6A1.
Worn rod bearing Crank pin and connecting rod bearing
inspection in Section 6A1.
Worn crank pin Crank pin and connecting rod bearing
inspection in Section 6A1.
Loose connecting rod nuts Connecting rod installation in Section
6A1.
Low oil pressure Previously outlined.
Low oil pressure Previously outlined.
Worn bearing Crankshaft and bearing inspection in
Section 6A1.
Worn crankshaft journal Crankshaft and bearing inspection in
Section 6A1.
Loose bearing cap bolts Crankshaft inspection in Section 6A1.
Excessive crankshaft thrust play Crankshaft thrust play inspection in
Section 6A1.
Overheating
Inoperative thermostat Thermostat in Section 6B.
Poor water pump performance Water pump in Section 6B.
Clogged or leaky radiator Radiator in Section 6B.
Improper engine oil grade Engine oil and oil filter change in Sec-
tion 0B.
Clogged oil filter or oil strainer Oil pressure check in Section 6A1.
Poor oil pump performance Oil pressure check in Section 6A1.
Faulty radiator fan control system Radiator fan control system in Section
6E1.
Dragging brakes Trouble diagnosis in Section 5.
Slipping clutch Trouble diagnosis in Section 7C.
Blown cylinder head gasket Cylinder head in Section 6A1. Condition Possible Cause Correction
6-30 ENGINE GENERAL INFORMATION AND DIAGNOSIS
Improper engine
idling or engine fails
to idleFaulty spark plug Spark plugs in Section 6F1.
Leaky or disconnected high-tension cord High-tension cords in Section 6F1.
Faulty ignition coil with ignitor Ignition coil in Section 6F1.
Fuel pressure out of specification Diagnostic Flow Table B-3.
Leaky manifold, throttle body, or cylinder
head gasket
Malfunctioning EGR valve (if equipped) EGR system in Section 6E1.
Faulty idle air control system Diagnostic Flow Table B-4.
Faulty evaporative emission control system EVAP control system in Section 6E1.
Faulty EGR system (if equipped) EGR system in Section 6E1.
Faulty fuel injector(s) Diagnostic Flow Table B-1.
Poor performance of ECT sensor, TP sensor
or MAP sensorECT sensor, TP sensor or MAP sensor
in Section 6E1.
Faulty ECM
Loose connection or disconnection of vacuum
hoses
Malfunctioning PCV valve PCV system in Section 6E1.
Engine overheating Refer to “Overheating” section.
Low compression Previously outlined.
Excessive hydrocar-
bon (HC) emission
or carbon monox-
ide (CO)Faulty spark plug Spark plugs in Section 6F1.
Leaky or disconnected high-tension cord High-tension cords in Section 6F1.
Faulty ignition coil with ignitor Ignition coil assembly in Section 6F1.
Low compression Refer to “Low compression” section.
Lead contamination of three way catalytic
converterCheck for absence of filler neck restric-
tor.
Faulty evaporative emission control system EVAP control system in Section 6E1.
Fuel pressure out of specification Diagnostic Flow Table B-3.
Closed loop system (A/F feed back compen-
sation) fails
Faulty TP sensor
Poor performance of ECT sensor or MAP
sensorTP sensor in Section 6E1.
ECT sensor or MAP sensor in Section
6E1.
Faulty injector(s) Diagnostic Flow Table B-1
Faulty ECM
Engine not at normal operating temperature
Clogged air cleaner
Vacuum leaks
Excessive nitrogen
oxides (NOx) emis-
sionImproper ignition timing See section 6F1.
Lead contamination of catalytic converter Check for absence of filler neck restric-
tor.
Faulty EGR system (if equipped) EGR system in Section 6E1.
Fuel pressure out of specification Diagnostic Flow Table B-3.
Closed loop system (A/F feed back compen-
sation) fails
Faulty TP sensor
Poor performance of ECT sensor or MAP
sensorTP sensor in Section 6E1.
ECT sensor or MAP sensor in Section
6E1.
Faulty injector(s) Diagnostic Flow Table B-1
Faulty ECM Condition Possible Cause Correction
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-31
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 condi-
tion, 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 and output
from ECM as commands and there may be cases where the engine or actuator is not operating (in the condi-
tion) 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.
The triangle (
∆) marked data in the table below can not be read for vehicle without immobilizer indi-
cator lamp.
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 DATA VEHICLE CONDITION NORMAL CONDITION/
REFERENCE VALUES
✱FUEL SYSTEM B1
(FUEL SYSTEM STATUS)At specified idle speed after warming up CLOSED (closed loop)
✱CALC LOAD
(CALCULATED LOAD
VALUE)At specified idle speed with no load after
warming up3 – 9%
At 2500 r/min with no load after warming up 12 – 17%
✱COOLANT TEMP.
(ENGINE COOLANT
TEMP.)At specified idle speed after warming up 80 – 100°C, 176 – 212°F
✱SHORT FT B1
(SHORT TERM FUEL
TRIM)At specified idle speed after warming up– 20 – +20%
✱LONG FT B1
(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 up30 – 37 kPa,
220 – 280 mmHg
✱ENGINE SPEED At idling with no load after warming up Desired idle speed
±50 r/min
✱VEHICLE SPEED At stop 0 km/h, 0 MPH
✱IGNITION ADVANCE
(IGNITION TIMING
ADVANCE FOR NO.1 CYL-
INDER)At specified idle speed with no load after
warming up6 – 16° BTDC
✱INTAKE AIR TEMP. At specified idle speed after warming up Ambient temp. :
+15°C (59°F)
–5°C (23°F)
✱MAF
(MASS AIR FLOW RATE)At specified idle speed with no load after
warming up1 – 4 gm/sec
At 2500 r/min with no load after warming up 4 – 9 gm/sec
6-34 ENGINE GENERAL INFORMATION AND DIAGNOSIS
IGNITION ADVANCE (IGNITION TIMING ADVANCE FOR NO.1 CYLINDER, °)
Ignition timing of NO.1 cylinder is commanded by ECM. 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 sensor,
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 exhaust manifold (pre-catalyst).
OXYGEN SENSOR B1 S2 (HEATED OXYGEN SENSOR-2, V)
It indicates output voltage of HO2S-2 installed on exhaust pipe (post-catalyst). It is used to detect catalyst dete-
rioration.
DESIRED IDLE (DESIRED IDLE SPEED, rpm)
The Desired Idle Speed is an ECM internal parameter which indicates the ECM 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 (but injector
drive time of NO.1 cylinder for multiport fuel injection).
IAC FLOW DUTY (IDLE AIR (SPEED) CONTROL DUTY, %)
This parameter indicates current flow time rate within a certain set cycle of IAC valve (valve opening rate) which
controls the amount of bypass air (idle speed).
TOTAL FUEL TRIM (%)
The value of Total Fuel Trim is obtained by putting values 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 stoichiometrical.
BATTERY VOLTAGE (V)
This parameter indicates battery positive voltage inputted from main relay to ECM.
CANIST PURGE DUTY (EVAP CANISTER PURGE FLOW DUTY, %)
This parameter indicates valve ON (valve open) time rate within a certain set cycle of EVAP purge solenoid
valve which controls the amount of EVAP purge.
0% means that the purge valve is completely closed while 100% is a fully open valve.
CLOSED THROTTLE POSITION (ON/OFF)
This parameter will read ON when throttle valve is fully closed, or OFF when the throttle is not fully closed.
FUEL CUT (ON/OFF)
ON : Fuel being cut (output signal to injector is stopped)
OFF : Fuel not being cut
6-36 ENGINE GENERAL INFORMATION AND DIAGNOSIS
INSPECTION OF ECM AND ITS CIRCUITS
ECM and its circuits can be checked at ECM wiring couplers by
measuring voltage and resistance.
VOLTAGE CHECK
1) Remove ECM (1) from vehicle body referring to Section 6E.
2) Check voltage at each terminal of couplers (2) connected.CAUTION:
ECM cannot be checked by itself. It is strictly prohibited
to connect voltmeter or ohmmeter to ECM with coupler
disconnected from it.
NOTE:
As each terminal voltage is affected by the battery volt-
age, confirm that it is 11 V or more when ignition switch
is ON.
1
1. ECM
2. ECM couplers (Viewed from harness side)
C42 (31P) C41 (24P) G02 (17P)1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17 18 19 20 21
22 23 24 25 26 28 27 29 30 315 6
1 2 3 4 5 6 7
11 12
9 10 11 13 12 14 15 16
16 171 2
7 8
13 14 3 4
9 10
15 17 188
19 20 21 22 23 24
2
1
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-43
Resistance Check
1) Disconnect ECM couplers from ECM with ignition switch
OFF.
2) Check resistance between each terminal of connectors dis-
connected.
TERMINAL RESISTANCE TABLE
For TYPE A (Refer to NOTE in “ECM VOLTAGE VALUES TABLE” for applicable model) CAUTION:
Never touch terminals of ECM itself or connect voltmeter
or ohmmeter.
CAUTION:
Be sure to connect ohmmeter probe from wire harness
side of coupler.
Be sure to turn OFF ignition switch for this check.
Resistance in table below represents that when parts
temperature is 20°C (68°F).
1. ECM coupler disconnected
2. Ohmmeter
TERMINALS CIRCUIT STANDARD
RESISTANCE
C42-7 to G02-6 HO2S-1 heater (if equipped) 5.0 – 6.4 Ω
C41-4 to G02-6 HO2S-2 heater (if equipped) 12.0 – 14.3 Ω
C42-9 to C41-5/6 No.1 injector 11.3 – 13.8 Ω
C42-21 to C41-5/6 No.2 injector 11.3 – 13.8 Ω
C42-31 to C41-5/6 No.3 injector 11.3 – 13.8 Ω
C42-8 to C41-5/6 No.4 injector 11.3 – 13.8 Ω
C41-2 to C41-5/6 EGR valve (stepper motor coil 1) (if equipped) 20 – 24 Ω
C41-9 to C41-5/6 EGR valve (stepper motor coil 2) (if equipped) 20 – 24 Ω
C41-8 to C41-5/6 EGR valve (stepper motor coil 3) (if equipped) 20 – 24 Ω
C41-17 to C41-5/6 EGR valve (stepper motor coil 4) (if equipped) 20 – 24 Ω
C42-4 to C41-5/6 EVAP canister purge valve 30 – 34 Ω
C41-19 to G02-6 Fuel pump relay 56 – 146 Ω
C41-1 to Body ground A/C compressor clutch 3 – 5.5 Ω
C41-18 to C41-5/6 Radiator fan control relay No.1 56 – 146 Ω
C41-10 to G02-17 Main relay 56 – 146 Ω
C42-1 to Body ground Ground Continuity
C42-2 to Body ground Ground Continuity
C42-3 to Body ground Ground Continuity