ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-5
FUEL PRESSURE RELIEF PROCEDURE
CAUTION:
This work must not be done when engine is hot. If done so,
it may cause adverse effect to catalyst.
After making sure that engine is cold, release fuel pressure as fol-
lows.
1) Place transmission gear shift lever in “Neutral” (Shift selector le-
ver to “P” range for A / T model), set parking brake, and block
drive wheels.
2) Remove relay box cover.
3) Disconnect fuel pump relay (1) from relay box (2).
4) Remove fuel filler cap to release fuel vapor pressure in fuel tank
and then reinstall it.
5) Start engine and run it till it stops for lack of fuel. Repeat cranking
engine 2-3 times for about 3 seconds each time to dissipate fuel
pressure in lines. Fuel connections are now safe for servicing.
6) Upon completion of servicing, connect fuel pump relay to relay
box and install relay box cover.
FUEL LEAKAGE CHECK PROCEDURE
After performing any service on fuel system, check to make sure
that there are no fuel leakages as follows.
1) Turn ON ignition switch for 2 seconds (to operate fuel pump) and
then turn it OFF.
Repeat this (ON and OFF) 3 or 4 times and apply fuel pressure
to fuel line. (till fuel pressure is felt by hand placed on fuel feed
hose.)
2) In this state, check to see that there are no fuel leakages from
any part of fuel system.
6-6 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
ENGINE DIAGNOSIS
GENERAL DESCRIPTION
This vehicle is equipped with an engine and emission control system which are under control of ECM (PCM).
The engine and emission control system in this vehicle are controlled by ECM (PCM). ECM (PCM) has an On-
Board Diagnostic system which detects a malfunction in this system and abnormality of those parts that influence
the engine exhaust emission. When diagnosing engine troubles, be sure to have full understanding of the outline
of “On-Board Diagnostic System” and each item in “Precaution in Diagnosing Trouble” and execute diagnosis ac-
cording to “ENGINE DIAGNOSTIC FLOW TABLE”.
There is a close relationship between the engine mechanical, engine cooling system, ignition system, exhaust sys-
tem, etc. and the engine and emission control system in their structure and operation. In case of an engine trouble,
even when the malfunction indicator lamp (MIL) doesn’t turn ON, it should be diagnosed according to this flow table.
ON-BOARD DIAGNOSTIC SYSTEM
ECM (PCM) in this vehicle has following functions.
When the ignition switch is turned ON with the engine at a stop,
malfunction indicator lamp (MIL) (1) turns ON to check the bulb
of the malfunction indicator lamp (1).
When ECM (PCM) detects a malfunction which gives an adverse
effect to vehicle emission while the engine is running, it makes the
malfunction indicator lamp (1) in the meter cluster of the instru-
ment panel turn ON or flash (flashing only when detecting a mis-
fire which can cause damage to the catalyst) and stores the mal-
function area in its memory.
(If it detects that continuously 3 driving cycles are normal after de-
tecting a malfunction, however, it makes MIL (1) turn OFF al-
though DTC stored in its memory will remain.)
As a condition for detecting a malfunction in some areas in the
system being monitored by ECM (PCM) and turning ON the mal-
function indicator lamp (1) due to that malfunction, 2 driving cycle
detection logic is adopted to prevent erroneous detection.
When a malfunction is detected, engine and driving conditions
then are stored in ECM (PCM) memory as freeze frame data. (For
the details, refer to description on Freeze frame data.)
It is possible to communicate by using not only SUZUKI scan tool
(Tech-1) (2) but also generic scan tool. (Diagnostic information
can be accessed by using a scan tool.)
ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-13
MALFUNCTION INDICATOR LAMP (MIL)
CHECK
1) Turn ON ignition switch (but the engine at stop) and check that
MIL lights.
If MIL does not light up (or MIL dims), go to “Diagnostic Flow
Table A-1” for troubleshooting.
2) Start engine and check that MIL turns OFF.
If MIL remains ON and no DTC is stored in ECM (PCM), go to
“Diagnostic Flow Table A-2” for troubleshooting.
DIAGNOSTIC TROUBLE CODE (DTC) CHECK
1) Prepare SUZUKI scan tool (Tech-1) or generic scan tool.
2) With ignition switch OFF, connect it to data link connector (DLC)
(1) located on underside of instrument panel at driver’s seat side.
Special Tool:
(A): SUZUKI scan tool
(B): Mass storage cartridge
(C): 16 / 14 pin DLC cable
3) Turn ignition switch ON and confirm that MIL lights.
4) Read DTC, pending DTC and freeze frame data according to
instructions displayed on scan tool and print it or write it down.
Refer to scan tool operator’s manual for further details.
If communication between scan tool and ECM (PCM) is not pos-
sible, check if scan tool is communicable by connecting it to
ECM (PCM) in another vehicle. If communication is possible in
this case, scan tool is in good condition. Then check data link
connector and serial data line (circuit) in the vehicle with which
communication was not possible.
5) After completing the check, turn ignition switch off and discon-
nect scan tool from data link connector.
6-14 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
DIAGNOSTIC TROUBLE CODE (DTC)
CLEARANCE
1) Connect SUZUKI scan tool (Tech-1) or generic scan tool to data
link connector in the same manner as when making this connec-
tion for DTC check.
2) Turn ignition switch ON.
3) Erase DTC and pending DTC according to instructions dis-
played on scan tool. Refer to scan tool operator’s manual for fur-
ther details.
4) After completing the clearance, turn ignition switch off and dis-
connect scan tool from data link connector.
NOTE:
DTC and freeze frame data stored in ECM (PCM) memory
are also cleared in following cases. Be careful not to clear
them before keeping their record.
When power to ECM (PCM) is cut off (by disconnecting
battery cable, removing fuse or disconnecting ECM
(PCM) connectors for 30 sec. or longer)
When the same malfunction (DTC) is not detected again
during 40 engine warm-up cycles.
6-20 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
ENGINE BASIC INSPECTION
This check is very important for troubleshooting when ECM (PCM) has detected no DTC and no abnormality has
been found in visual inspection.
Follow the flow table carefully.
STEP
ACTIONYESNO
1Was “ENGINE DIAG. FLOW TABLE” performed?Go to Step 2.Go to “ENGINE DIAG.
FLOW TABLE”.
2Check battery voltage.
Is it 11 V or more?Go to Step 3.Charge or replace
battery.
3Is engine cranked?Go to Step 4.Go to “DIAGNOSIS”
in Section 6G.
4Does engine start?Go to Step 5.Go to Step 7.
5Check idle speed as follows.
1) Warm up engine to normal operating temp.
2) Shift transmission to neutral position for M / T
(“P” position for A / T).
3) All of electrical loads are switched off.
4) Check engine idle speed with scan tool.
See Fig. 1.
Is it 800 – 900 r / min.?Go to Step 6.Go to “ENGINE
DIAGNOSIS TABLE”.
6Check ignition timing as follows.
1) Select “MISC” mode on SUZUKI scan tool and
fix ignition timing to initial one. See Fig. 2.
2) Using timing light (1), check initial ignition timing.
See Fig. 3.
Is it 5 ± 3 BTDC at specified idle speed?Go to “ENGINE
DIAGNOSIS TABLE”.Check ignition control
related parts referring
to Section 6F.
7Check immobilizer system malfunction as follows.
1) Check immobilizer indicator lamp for flashing.
Is it flashing when ignition switch is turned to ON
position?Go to “DIAGNOSIS” in
Section 8A.Go to Step 8.
8Check fuel supply as follows.
1) Check to make sure that enough fuel is filled in fuel
tank.
2) Turn ON ignition switch for 2 seconds and then
OFF. See Fig. 4.
Is fuel return pressure (returning sounds) felt from fuel
feed hose (1) when ignition switch is turned ON?Go to Step 10.Go to Step 9.
9Check fuel pump for operating.
1) Was fuel pump operating sound heard from fuel
filler for about 2 seconds after ignition switch ON
and stop?Go to “DIAG. FLOW
TABLE B-3”.Go to “DIAG. FLOW
TABLE B-2”.
10Check ignition spark as follows.
1) Disconnect injector coupler.
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 11.Go to “DIAGNOSIS”
in Section 6F.
11Check fuel injector for operation as follows.
1) Install spark plugs and connect injector
connectors.
2) Check that fuel is injected out in conical shape
from fuel injector when cranking.
Is it in good condition?Go to “ENGINE
DIAGNOSIS TABLE”.Go to “DIAG. FLOW
TABLE B-1”.
6-22 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
ENGINE DIAGNOSIS TABLE
Perform troubleshooting referring to following table when ECM (PCM) has detected no DTC and no abnormality
has been found in visual inspection and engine basic inspection previously.
Condition
Possible CauseReferring Item
Hard Starting
(Engine cranks OK)Ignition system out of order
Faulty spark plug
Leaky high-tension cord
Loose connection or disconnection of high-
tension cords or lead wires
Faulty ignition coil
Fuel system out of order
Dirty or clogged fuel hose or pipe
Malfunctioning fuel pump
Air inhaling from intake manifold gasket or
throttle body gasket
Fuel injector resistor malfunction
Engine and emission control system out of
order
Faulty idle control system
Faulty ECT sensor or MAP sensor
Faulty ECM (PCM)
Low compression
Poor spark plug tightening or faulty gasket
Compression leak from valve seat
Sticky valve stem
Weak or damaged valve springs
Compression leak at cylinder head gasket
Sticking or damaged piston ring
Worn piston, ring or cylinder
Others
Malfunctioning PCV valve
Spark plugs in Section 6F
High-tension cords in Section 6F
High-tension cords in Section 6F
Ignition coil in Section 6F
Diagnostic Flow Table B-3
Diagnostic Flow Table B-3
Fuel injector resistor in Section 6E1
Diagnostic Flow Table P0505
ECT sensor or MAP sensor in
Section 6E1
Compression check in Section
6A
Spark plugs in Section 6F
Valves inspection in Section 6A
Valves inspection in Section 6A
Valve springs inspection in
Section 6A
Cylinder head inspection in
Section 6A
Cylinders, pistons and piston rings
inspection in Section 6A
Cylinders, pistons and piston rings
inspection in Section 6A
PCV system in Section 6E1
6-24 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
ConditionPossible CauseReferring Item
OverheatingInoperative thermostat
Poor water pump performance
Clogged or leaky radiator
Improper engine oil grade
Clogged oil filter or oil strainer
Poor oil pump performance
Faulty radiator fan control system
Dragging brakes
Slipping clutch
Blown cylinder head gasketThermostat in Section 6B
Water pump in Section 6B
Radiator in Section 6B
Engine oil and oil filter change in
Section 0B
Oil pressure check in Section 6A
Oil pressure check in Section 6A
Radiator fan control system in
Section 6E1
Trouble diagnosis in Section 5
Trouble diagnosis in Section 7C
Cylinder head in Section 6A
Poor gasoline
mileageIgnition system out of order
Leaks or loose connection of high-tension cord
Faulty spark plug (improper gap, heavy deposits
and burned electrodes, etc.)
Engine and emission control system out of
order
High idle speed
Poor performance of TP sensor, ECT sensor or
MAP sensor
Faulty fuel injector
Faulty fuel injector resistor
Faulty ECM (PCM)
Low compression
Others
Poor valve seating
Dragging brakes
Slipping clutch
Thermostat out of order
Improper tire pressure
High-tension cords in Section 6F
Spark plugs in Section 6F
Refer to item “Improper engine
idle speed” previously outlined
TP sensor, ECT sensor or MAP
sensor in Section 6E1
Diagnostic Flow Table B-1
Fuel injector resistor in Section 6E1
Previously outlined
Valves inspection in Section 6A
Trouble diagnosis in Section 5
Trouble diagnosis in Section 7C
Thermostat in Section 6B
Refer to Section 3F
Excessive engine
oil consumptionOil leakage
Blown cylinder head gasket
Leaky camshaft oil seals
Oil entering combustion chamber
Sticky piston ring
Worn piston and cylinder
Worn piston ring groove and ring
Improper location of piston ring gap
Worn or damaged valve stem seal
Worn valve stem
Cylinder head in Section 6A
Camshaft in Section 6A
Piston cleaning in Section 6A
Pistons and cylinders inspection
in Section 6A
Pistons inspection in Section 6A
Pistons assembly in Section 6A
Valves removal and installation in
Section 6A
Valves inspection in Section 6A
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